Metabolism and Physical Activity Paradox.

How Many Calories Are You Really Burning with Exercise?

By Elena Voropay

“For the first time ever, overweight people outnumber average people in America. Doesn't that make overweight the average then? Last month you were fat, now you're average - hey, let's get a pizza!” (Jay Leno).

The body is designed to burn calories throughout the day, and there is no better way to give yourself a lift than by doing something constructive to your body through exercise. Energy expenditure in exercise is the second largest and most variable component of total energy expenditure. Generally, your body in motion can speed up your metabolic rate for 15 - 30% of daily calorie burn depending on how active or restless you are. This includes not just your structured exercise program, planned workouts, but something you do unintentionally, such as shivering and fidgeting. But the harder you push yourself, the more calories you burn. During heavy physical exertion, the muscles may burn through as much as 1,000 calories per hour!

Now you need to get the facts straight. There is a huge difference between being active, engaging in exercise and training. Exercise and training have as much in common as Yoga and real army boot camp. Exercising involves some walking, maybe running, a few push-ups or crunches here and there. Exercise is cute. Training means really pushing yourself to the limits, breaking through the plateaus of mind and body, knowing exactly what you want to achieve with every step you take, with every move you make. Training is mighty.

Whether you want to burn calories, boost your BMR, build muscles, or simply get stronger, you will achieve much better results if you know what to do and how to do it. Here comes the body composition in sync - muscles can burn only 20% or so of the total energy expenditure at rest, but during strenuous exercise the rate of energy expenditure of the muscles may go up to 50-fold or more. Apart from the energy used in the exercise itself, regular physical activity affects BMR because it affects body composition. Of course you know that regularly active people have higher BMRs than non-active individuals. This means that even when these folks are resting, they are melting away as much as 5 - 10% calories more. Since BMR accounts for about 75% of total daily energy expenditure, this is a significant difference.

Your calorie expenditure obviously increases above your resting rate when you exercise, with the magnitude of this increase dependent on how long and hard you exercise. If you wonder whether you continue to burn “extra” calories after we finish exercising, the answer is the one you are looking for: “Yes!” Your energy expenditure remain elevated above BMR for a period of time even after you stop the exercise. Plus, the amount of post-exercise elevation of energy expenditure depends primarily on how hard you exercise and to a lesser degree on how long you exercise.

Additional Movement

Even though regularly scheduled aerobic and anaerobic exercise is best for boosting metabolism and aiding weight loss, any extra movement helps burn calories. If it sounds silly, check what recent studies show - individuals with higher levels of "spontaneous physical activity," such as fidgeting, or taking a few steps here and there while talking on phone, or changing TV channels, burn significantly more calories than non-fidgeters. These types of people tend to have trouble sitting still, do a lot of pacing and tap their feet and bounce their knees when sitting. Fidgeting can burn as many as 800 calories each day!

That's another good reason to get your body moving as often as possible! Most recently, this non-structured movement has been coined the name NEAT, for non-exercise activity thermogenesis. Since energy used during exercise is the only form of energy expenditure that you have any control over, take advantage of this phenomenon and start moving more!

Exercise also has a great food-brain-hormonal link - it slows digestion and keeps you feeling full longer, blunts appetite-stimulating hormones and also helps maintain normalized blood glucose levels so you feel less hungry.

Exercise Like Crazy And Still Fat?

You are probably not burning as many calories as you think you are. Even if you are already getting enough exercise daily, consider that numerous researches show that most people generally underestimate how much they eat, and overestimate how much they exercise. Popular belief is that the primary cause of weight gain is an energy intake that constantly exceeds the amount of physical activity or energy expenditure of an individual.

When it comes to losing weight, most of us follow a simple formula: burning more calories + eating fewer calories = weight loss. The cornerstone to shedding bodyfat is a controlled method of calorie reduction. Specifically, eating less than your body needs are. As your calorie intake declines, your body begins using bodyfat for fuel, which makes your physique look harder, denser and, dammit, healthier.

The lie has been out there for a long while by now and it looks like most of us have heard it enough times to actually start believing that exercise burns thousands and thousands of calories, increases your metabolic rate which stays up long after you finish training. Extensive research has shown that aerobic exercise can significantly increase fat-burning. Exercise is one way we try to burn more calories, so we hit the gym or pick up a pair of weights thinking we’ll eventually see the number on the bodyfat scale take its way down. Unfortunately, it doesn’t always work that way.

First, zealous cuts in calories, prolonged dieting plus sharp increases in aerobic work trigger the body's built-in metabolic reaction – the dangerous starvation response in which the body slows its ability to burn calories and bodyfat for long-term survival. Second, as you reduce calories, your body burns not just the fat, but it also increases the amount of protein used to fuel normal activities, meaning you risk losing muscle tissue, too. Often, the stimulus signaling the body to spare muscle is not present. Your legs may burn, your breathing may intensify, your heart will beat faster, you may be exhausted and fatigued, but resistance used in aerobic exercise is often not intense enough to trigger the body's protective response. Third, as your energy levels dip, your ability to work out with intensity high enough goes down as well.

Now, get ready for more bad news – you really don't spend or need as much energy to power your training!

Most people grossly overestimate the number of calories expended as a result of steady-state activities like aerobics, running, biking, stair climbing or rowing. Believe it or not, but a kilogram of body fat (an equivalent of 7,000 calories) is enough to meet the energy demands of 10 to 20 hours of continuous activity! That's right, folks. You need to exercise for 20 hours straight to burn a mere kilogram of fat. What's worse, when the weight comes off, you can't really see that much of a difference. Imagine taking 5 sticks of butter each worth of 200 grams. It looks big. Now imagine spreading these same 5 sticks all over your entire body. It would probably be around 1 millimeter in thickness being melted from under your skin. And all this after 10 hours of boxing!!!

An average woman vigorously riding a stationary bicycle may believe she's "burning up" her cellulite every minute. The sweat is dripping off her forehead, the poor thing is puffing and counting seconds waiting for the grueling workout to be done and over with. Well, if she only knew that after riding for 45 to 60 minutes the total amount of calories nuked is equal to two Oreo cookies!

If you exercise away 300 calories and only compensate by eating 200 more, you can lose weight. But exercise burns fewer calories than many people think. Let’s say you go to the gym and burn off 3,500 calories every week - that’s 700 calories a session, five times a week. Since a kilogram of fat is 7,000 calories (or a pound of fat is equivalent to 3,500 calories), you should be ½ kg or one pound slimmer for every week we exercise provided your diet doesn't change. How long will this fat-nuking continue week after week? Theoretically, you could lose 182, 000 calories in a year! That is almost 24 kilograms or 52 pounds of pure fat!

Walking for 40 minutes a day may spend an an extra 150 calories - less than the average chocolate chip cookie! If you spend 30 or 60 or 90 minutes a day burning off excess calories at the gym, will you inevitably lose weight? What if you spend the same amount of time sitting on the couch and complaining about your fat genes? How about a math test.

Take a simple ingredient which most of us add as an extra and don't even consider when we're tallying up our calories at the end of the day. Mayo is added to sandwiches, used as a dip for chips or is mixed into healthy fresh crispy vegetables to make a salad. Each tablespoon of mayonnaise has 110 calories. If you're downing 5 sandwiches a week from the local deli, eat just one salad a day, and if each has even a bit of mayonnaise, you're racking up the extra calories – 1420! Now do the math. To work out just the mayo, a man of 90-kg weight would need to walk for 300 minutes, at least! So when you think about it, doesn't mustard look - and taste - better right about now? So, many times the problem is not that we don't burn enough calories, it's that we put too many calories down our necks.

How Much Fuel Do We Need?

Today, exercise is as much of a cultural and social activity as eating. In this modern day of cell phones, computers and television, we don't need to run a marathon just to announce that your freshest bison has been beaten. Still, we've been our own best engines for most of our years. All activities, be it going shopping, getting a newspaper from your mailbox, packing gym bag or the actual activity of working out require both aerobic and anaerobic power. How can each activity use enough muscle mass to work a human at or near maximum power for extended periods? How can you be coupled to the task so that your greatest physical and emotional potential of that power performs what you intend? You need to eat. Food is the only energy source our muscles can use to make exercise possible. But check your plate and your palate to make any justifications.

Studies show that there are about 1,000 Calories between being satisfied and feeling full. Even more frightening is that there is a lag of around 2,000 to 3,000 calories between feeling full and feeling stuffed. This means that if you go out to an all-you-can-eat food bar and leave feeling stuffed, you may have consumed as many as 4,000 unneeded calories. If they all get absorbed, weight gain is inevitable – no less than 400 grams of pure fat. When this happens, at Thanksgiving Dinner for example, most people would typically try to balance their surplus energy intake with surplus energy expenditure. They would go out for a jog the next day to "burn off those calories". But to burn off that many calories would require you to jog continously for 27 hours!

Still, for those who cannot control their appetite, they need to know whether their intakes of nutrients are “justified” by exercise. In a 2004 University of Alabama study, normal weight women overestimated the amount of physical activity they did in one day (formal exercise plus activities of daily living) by 600 calories. Overweight women overestimated it by 900 calories. This is just an example. What's more, studies repeatedly show that people underestimate how many calories they eat which doubles the trouble. Watch out for psychological hunger, the attitude that says, “I deserve to eat as much as I want because I had a hard workout”. In the first place, don't ever treat your workout as a way to justify the binges. What you eat should be a valuable fuel, an energy source for your body which will help you enjoy life and do all sorts of fun stuff. Unfortunate as it is, many people live to eat. Should be the other way – you eat to live.

I read a good joke a while ago: “The biggest loser at my weight-loss club was an elderly woman. "How'd you do it?" we asked. "Easy," she said. "Every night I take my teeth out at six o'clock." While I am not suggesting for you to terminate your food intake before the sun goes down (chances are you will eat a lot more than usual prior to this hour if you know that your body will be starving), but take an advice from Steve Blair, a University of South Carolina exercise scientist and a co-author of the AHA-ACSM guidelines. He started running in his thirties and has run close to 80,000 miles in 38 years. Back then, he was “short, fat, and bald”. At age 68 he hasn't changed much: he is still short, but fatter and balder. He estimates that he gained about 30 pounds.

In an article “We can't work it out” by Gary Taubes first published on www.guardian.co.uk on Sunday 28 October 2007 and then in the Observer on Sunday 28 October 2007 (on p.58 of the Comment & features section), the author says:

“When I asked Blair whether he thought he might be leaner had he run even more, he had to think about it. “I don’t see how I could have been more active,” he said. “Thirty years ago, I was running 50 miles a week. I had no time to do more. But if I could have gone out over the last couple of decades for two to three hours a day, maybe I would not have gained this weight.” And maybe he would have anyway. If we trust the AHA-ACSM report he co-authored, there is little reason to believe that the amount he runs makes any difference. Nonetheless, Blair personally believes he would be fatter still if he hadn’t been running. Why?

There was a time when virtually no one believed exercise would help a person lose weight. Until the sixties, clinicians who treated obese and overweight patients dismissed the notion as naïve. When Russell Wilder, an obesity and diabetes specialist at the Mayo Clinic, lectured on obesity in 1932, he said his fat patients tended to lose more weight with bed rest, “while unusually strenuous physical exercise slows the rate of loss.”

What would you do – switch from drinking a bottle of regular soda to a bottle of diet pop or run for an hour? It is hard to find time to train, never mind training itself is not an easy activity.

Our bodies also have some kind of well-explored but not completely understood regulatory mechanism that works to keep our energy intake and output in balance. This is why for many people, problems start shortly after they start a new diet or an exercise program. If you ever tried to lose weight, you probably started out by burning more calories than you take in and stayed in caloric deficit by exercising more and eating less. However, soon you probably found that the weight and fat loss slowed and eventually came to a halt even though you continued to exercise and maintain the same food intake.

We call this the exercise/weight loss paradox where the body has figured out a way to establish a new food intake and energy expenditure balance. Indeed, it would be naive to think that simply by training more you would significantly increase resting or non-resting energy expenditure (NREE) for a long time. Similarly, watching every calorie that goes down to your stomach and calculating whether you burn every one of these calories is not going to give any answers either.

Human metabolic energy expenditure is remarkably flexible. Considering that all reactions in the body, including digestion of food and physical movement, consume calories, the conclusions that the endogenous reactions that take place in response to new stimuli (especially in the untrained body) are many times greater as the body makes the changes necessary to become accustomed to the new workload or a new diet. When you start an exercise program, the reactions include repairing muscle damage and subsequent hormonal changes accompanied by core temperature changes.

Depending on your degree of physical conditioning, oxidative energy expenditure can increase 10 - 20 fold between resting and peak effort. But this effect doesn't last. There are well-controlled studies that support the notion that exercise (especially aerobic) does not continue to support an increase in one’s 24-hour metabolic rate. Therefore, any positive impact an exercise has on metabolism may be an acute, transitory effect. Conversely, once this adaptation to exercise period has passed, the next effect may be down-regulation of metabolic expenditure in response to the energy imbalance induced by exercise. Paradoxically, REE may actually be reduced from its pre-exercise level because the body became so efficient at using its energy. Mostcurrent studies of populations ranging from the obese through to trained athletes support that chronic exercise can lower one’s REE and may also lower NREE.

This scientifically unexplained effect of too much exercise might be attributable to some form of Adaptive Thermogenesis (A.T.), a physiological response to some type of stress or change where the body adapts to undesirable conditions by actually reducing its energy requirements or by conserving energy. So, excessive aerobic exercise may result in a reduction in metabolic rate due to the body’s activation.

On the other hand, when you go on a calorie-restricted diet, your body senses that it is not getting enough nutrients and attempts to preserve the valuable stores to keep the homeostatic balance. Severe caloric restriction may reduce your ability to use energy by up to 15% in one week.

“In 1942, Louis Newburgh of the University of Michigan calculated that a 250-pound man expends only three calories climbing a flight of stairs—the equivalent of depriving himself of a quarter-teaspoon of sugar or a hundredth of an ounce of butter. “He will have to climb twenty flights of stairs to rid himself of the energy contained in one slice of bread!” Newburgh observed. So why not skip the stairs, skip the bread, and call it a day?” points Taubes.

Looks like I am talking you out of training... Wait a minite, don't throw out your joggers or weight training gloves just yet. Does this mean than we shouldn't take exercise seriously if we want to lose weight? Not so. There is a complex process going inside your body which changes your body in millions of ways beyond caloric expenditure.

The After-Burn

Ok, we cleared that once you are exercising, you tend to burn calories and fat. Even though the number are nothing to psyche about, it is still better than nothing at all. But not only that, your body keeps doing this after you have finished exercising - still burning calories, silently, efficiently, slyly. Even when you are having your post-training mega-meal, sleep and party, calories continue to get gobbled. This so-called “after-burn” effect is one of the biggest reasons most of us justify our extra portions after training. The “after-burn” is technically called as Exercise Post-Oxygen Consumption (or EPOC for short), and is supposed to be a key ingredient to weight loss, muscle gain and optimal efficient metabolism, or so we are told. In short, EPOC represents the additional energy your body burns above its resting level in order to return itself to the pre-exercise state.

The concept that the body keeps burning extra calories post workout isn't all lie. So, let's set the record straight. When you train, all of your cells are essentially working out too. And when you finish, the cells need to restore their functioning to pre-exercise levels and get to the stage of compensation and super-compensation. These processes require more of everything – oxygen, blood, fluid, amino acids, sugars, fats, vitamins, minerals and other materials to keep the bloody tissues re-building. In scientific terms, you body needs energy to replenish oxygen stores, resynthesise phosphagen (ATP-PC), remove waste products such as lactate, increase ventilation and blood circulation to all body tissues which also elevates body temperature above pre-exercise levels. This takes energy, aka calories, but not nearly as many as you might have heard.

Unfortunately, your metabolism doesn't double after training, as much as you wish for it to be true. It’s just a mere myth, at least according to an article titled Exercise Improves Fat Metabolism in Muscle but Does Not Increase 24-h Fat Oxidation (Exercises and Sport Sciences Review April 2009). "To our surprise, we have found that exercise has little, if any, effect on 24-hour fat oxidation [burning]," declared Edward Melanson, an exercise physiologist from the University of Colorado and lead author in an article from the April issue of Exercise and Sport Sciences Review.

In the study, 65 candidates were divided into four groups according to their lifestyles and exercise patterns: well trained, obese, sedentary, and lean. During the study they cycled at different exercise intensities, until they reached a point where they burned 400 calories. Then, trainees were monitored for 24 hours.The bad news is that there was no fat-burning afterglow. The moderate exercise itself burnt fat, but it didn't rev up the body's fat burning machine once the training has ceised. Pascal Imbreault who is a associate professor at Ottawa University ’s School of human kinetics, says that any kind of exercise after burn will usually finish after a period of 15 and 35 minutes. As for the glorified amount of energy your body needs after a workout - isn’t that impressive! Exercise is not a free ticket to all-you-can-stomach-pizza-joint. Any type of exercise has a "burn-off" effect after activity has ceased. However, the number of calories burned varies and is difficult to estimate.

Guess how much more do you really use for restoration and growth of your cellular material damaged by training? An additional 15% of the total calories expended during your workout. For example, some investigators reported that subjects burned only 15.5 additional calories following 30 minutes of cycling at 60-65% VO2 Max.

So, if you burned 300 calories actively exercising at the gym for an hour, you will burn about an extra 45 calories over the next two hours. This figure of 15% is on the high end as well. And then your metabolism will balance itself out.
While 45 calories may not sound like much, all those calories do add up. If you burn 300 calories 3 times in a week, that is an extra 135 calories. And this is just during the 2-hour-after-burn time.

In regards to muscle soreness you experience for days after training, that is your natural response to inflammation in the growing tissues. It's good, it's awsome, and you should definitely eat a bit more of good stuff to ensure that you will become bigger, stronger and leaner. But to get the stubborn muscle to their sore point, you need to train hard. Research has confirmed that the after-burn seems to depend mainly on workout intensity and duration, meaning how hard and how long you exercise.

Results from different studies don't give us a good picture of how many calories you can burn after training. The numbers for the “after-burn”range from 130 calories following 80 minutes of cycling, 162 calories after 160 minutes of cycling, to 73 calories after running for 80 minutes – all at the same intensity of 70% VO2 Max.

"It's not that exercise doesn't burn fat," said Edward Melanson, associate professor of medicine at the University of Colorado, "It's just that we replace the calories. People think they have a license to eat whatever they want, and our research shows that is definitely not the case. You can easily undo what you set out to do.”

Caloric deficit is necessary for fat loss, but how can you be sure it's fat, not muscle, you are losing? In reality you don't. If your calories get too low, muscle is spared at the expense of other tissues if there is a need for it. Worse yet, studies estimate that if you are on a calorie-restricted diet, you can burn as much as 100 grams of muscle tissue per day. This means that by the end of the week you will be 700 grams weaker! If you have been watching your body composition for a while, trained hard and heavy, you know that you need a lot of discipline in training and diet and it takes a long while to put on 700 grams of pure lean muscles. This is why you should slice in some high-intensity resistance training into your schedule. When your muscles are trained intensely and sets are taken to failure (the point where continued contraction is impossible), an alarm is triggered providing the body with stimulus necessary to understand that it requires more muscle. In other words, you are telling the body its protective margins are in danger and it must adapt to maintain itself.

Muscle is said to be the second most active tissue in the human body, after the brain. Unlike fat tissue, lean mass requires constant supply of oxygen, blood, nutrients, and this means more calories are needed to keep the tissue alive. So, how many more calories are we talking about? It is estimated that one kilogram of muscle requires around 75 - 100 calories per day to function. And this is it!

If you want to build lean mass, you can eat a lot more because calories fuel your training and if your body doesn't have the resources to train really hard, you won't be able to grow at all. During the muscle-building process the body adds muscle by synthesizing the protein you eat into new tissue which is an energy-demanding event. This premise has given millions of people a good excuse to eat, eat, and eat some more.

Because you can't build new tissues from the previously stored body fat, you have to get serious with your caloric intake to keep your body in an anabolic state. How serious? How about 8-9 meals a day, eating every two hours. After a month of high-intensity training and jars of peanut butter, cans of salmon, boxes of avocados, dozens of oatmeal packates, unlimited protein shakes and chicken breasts, varying carb intake, calculating calories, coordinating meal times you can gain around 5 kilograms in one month, and your BMR will increase by 250 to 500 calories per day - regardless of activity level. So, you can be watching TV all day and burn the 500 additional calories. Or you can run for an hour to burn the same amount of energy. Which is easier? I say TV. As long as the muscle increase is maintained, the body will continue to burn additional calories.

Most of the time the extra weight you put on will not be just pure lean flesh and you will gain some fat as well. Then, to lose that fat you can go back to the calorie-restricted diet, which will help you lose... up to 3 kilograms of muscle in one month's time (from the previously estimated 100 gram loss per day). Yep, it is that easy to lose the so-hard-to-gain lean mass.

This is the concept of discriminated weight loss - the body's ability to select which tissue to use for energy. The imperfections of human metabolism is something to think about twice before you go for a run or before you mindlessly down another protein-enriched shake after training.

So, at the end, with diet and exercise you are not burning the promised thousands of calories after all. But what is it about fat people being fat and skinny being skinny? Lean people are not those who have the willpower to exercise more and eat less. They are people whose bodies are programmed to send the calories they consume to the muscles to be burned rather than to the fat tissue to be stored. Welcome to the world of Arnold Schwarzenegger and Lance Armstrong. "You see something, you eat it." This is how these incredible athletes got to where they once have been. If you want to be anywhere near these guys, you must eat all the time and three squares a day are not going to cut it, no matter what your dieting friends tell you. To get the body into a tip-top shape of Arnie and Lance you need at least 5,000 calories per day. Hard-core athletes eat a lot, but they train hard and heavy too! And when I say that exercise doesn't burn as many calories as we tend to think, I am talking about 1/100th of the training intensity level of the above mentioned legends.

How many of us can have pride with bodies like his? Most people tend to go the other way with fuel partitioning being damaged. We eat and shunt off calories to fat tissue, not toward the muscles where they can be burned. To understand how and why this happens, we need to get through some basics of fat metabolism. When you get up from your comfortable couch and start moving, you work your muscles in an acute manner. This requires additional energy which is provided through the conversion of metabolic fuels you get from food calories into ATP, the base currency of chemical energy. Whether this caloric burn comes from fats, sugars or protein depends on your diet, exercise and overall resting metabolism. But let's focus on training for the moment.

We found out that in reality exercise doesn't burn as many calories as we would expect. I can say it from experience. When I had a surgery, I had to be immobile for a few months – not a fun state to be. Of course, my lean mass was nowhere near its former state when I returned to the gym afterwards – I couldn't lift as heavy, had no energy to walk. Just the thought of lifting the lightest dumbbell made me feel so exhausted that I thought my muscles stepped back in time and started giving me signals of Delayed Onset Muscle Soreness as if I did 100 sets to failure a day before. Fully loaded with claims like “muscles burn enourmous amounts of energy” and “a single workout will get your metabolism sky-high for days”, I ensured that my nutrient supply was in plenty. Heck, I wanted to build muscles and so I needed to provide my body with lots of calories which should've been used for lean construction, right? Guess what? After six months of training to failure (with a very low threshold for me as I was still in recovery) I haven't put on a kilo of any additional mass! Ok, I re-gained the 10 kg I had lost with surgery, but out of these 10 the majority was pure fat! That's right, the nasty lard I never wanted, the ugly blubber I worked so hard to lose before. What's even worse, I've been pushing my limits working out on an elliptical, stepper, doing boxing classes at least 3 times per week. Guess how much fat I've lost? Zero! Ziltch! Nada! What's been going on with my body remains a mystery.

I have used and applied every tactic known to man in order to lose weight – trained with weights, did the cardio, rested, cleaned up my diet to the point of counting grams of fiber, individual amino acids, single vitamins and minerals, drank liters of water... You get the point. The theory goes that our extremely sensitive and outrageously smart metabolic systems have a special sensor which determines how much energy is used and how much is absorbed. This sensor ensures that each individual maintains a certain weight pre-determined from birth. This is why comparing yourself to others in terms of mass, bodyfat and strength is too frustrating and clearly is a waste of time – not to mention it is harmful for self-esteem. So, no matter what you do, if mother nature – or your mom and dad – has made you to look like Cartman from the South Park cartoon, you can't get Brad Pitt's looks without surgical intervention.

The Lies and Truths About Caloric Burn

If you’re trying to lose weight with exercise, you may have used an activity calculator to determine how many calories you’re burning. For example, if you weigh 90 kg, and go jogging for 30 minutes, you will be able to burn about 400 calories. Not bad for a 30-minute workout, you might think, but are you getting the whole story? Not exactly. The truth is, exercise is a complicated business and there are a number of things that can affect how many calories you burn. Knowing what those variables are will help you set realistic goals and get the most out of your workouts.

Net Calories vs. Gross Calories:

Most calculators installed on cardio machines use activity, duration of your workout and your weight to come up with an estimate number of calories burned. This is known as gross calories. What we forget to factor in are the calories we would’ve burned if we weren’t exercising, also known as the net calories burned. The average man who weighs 90 kilograms (200 pounds) will use up 540 calories in one hour of shoveling snow; 400 calories of working out in the gym with weights; and around 100 calories during an hour of sleep.

So, if you trained during a time you normally watch TV, of course you are still burning more calories, but you need to subtract the calories you would’ve burned while watching TV in order to get a more accurate calculation. So, an hour of intense work actually melts 300 calories at max. It may seem like a small difference, half a burger to compare, but this difference becomes important, however, when you are trying to predict weight loss or gain.

As far as the activities are concerned, I will surely remember the torture of shoveling snow, but will not pay a slightest bit of attention to spending the same amount of calories if I stay at home and watch a movie for a couple of hours, check my e-mail (which usually takes me an hour or so) and cook dinner for my family (another hour).

If you’re tracking calories burned with exercise, you can get a more accurate number by subtracting the calories you would’ve burned if you weren't working out. For example, if you burned 200 calories while walking for 20 minutes and would've burned 50 calories if you sat at the computer, your net calories burned would be 150. You can also check you BMR (Basal Metabolic Rate) per unit of time, and than subtract this from the predicted number of calories nuked at exercise.

The Type of Workouts You Do:

Look at joggers and distance runners. They are slender, but not lean. They exercise a lot but have no muscle mass. They're weak, they can't generate power, and in spite of their slender appearance, metabolisms of joggers is slower than metabolisms of other athletes. While professional endurance athletes might have very low bodyfat levels, the average body fat content of jogging club members was 22% in one study. Strength and power athletes don't have any more fat tissue, but they have a lot more lean mass.

Aerobics:

While any exercise is good for the body, some activities do burn more calories than others. Weight-bearing activities like running, rope jumping or walking, burn more calories because gravity makes your body work harder. When doing non-weight-bearing exercises like cycling or swimming, there isn’t as much gravitational stress on the muscles, which means fewer calories are burned provided that the intensity levels are matched. However, these activities do have advantages. They’re less stressful on the joints and you can often do them more often and for longer. This can make up for the difference in calories burned with weight-bearing activities. Best bet is do cross-training where you interchange between impact and non-impact activities.

For example, if you want to burn more fat calories, you can run for 15 minutes, cycle for 15 minutes, than add another 15 on an elliptical or a rowing machine. If you’re able to do that, you will not only get your lipids or fats metabolised for energy with great efficiency, but work all your body parts in different ways, which also helps build cardiovascular endurance, stronger bones and connective tissue.

Weight Training:

Figuring out how many calories are burned during and after cardiovascular exercise is a lot easier than during resistance training. It is well understood in all exercise physiology and nutrition texts that for every litre of oxygen consumed, approximately 5 calories are burned. Since training with weights occurs in the anaerobic environment and the need for oxygen is minimal, it is difficult to equalize resistance training and aerobic exercise. You can find all sorts of figures – from 200 to 1000 calories burned in a single weight-training session.

This depends on a number of factors - weight loads or intensity, time allowed for rest periods, the types of exercises you choose, whether you train with free weights or on machines, how many reps and sets you complete, whether you do a full-body workout or a split routine. If intensity and duration is taken care of, using free weights instead of machines also adds to the energy expenditure because it forces your body to recruit more muscles to balance the weight, a superior advantage to the predetermined range of motion that machines have to offer. On average, a single weight-training session will yield a caloric burn of around 400 calories, but it can be a lot less for a beginner, for a woman, for an elderly person, and a lot higher for someone like Ronnie Coleman.

Resistance training also burns more calories after exercise. One study found that after a 30-minute full-body workout in which subjects trained with their 10 RM weights, the Resting Metabolic Rate was elevated by 20% for 2 days following the exercise session. In a 90-kg man, that percentage equates to an average 400 extra calories burned per day. Wow! Not bad for doing nothing at all.

Another study showed that a high intensity resistance training workout (2 sets, 8 reps, 85% of 8RM) burned twice as many calories (11 to be exact) versus low intensity session (2 sets, 15 reps, 45% 8RM) (a mere 5.5 calories). Generally, it takes anywhere from 15 minutes to 48 hours for the body to fully recover to a resting state. Obviously, if you train hard, really hard, you will need more time for recuperation, and thus more energy to balance the damage of training. This is all good, but if all your workouts are high intensity, you run the risk of overtraining and injury. So, listen to your body and use a training log to know where to draw the line. With time and experience, you'll find your own limits while keeping track of how hard you’re working.

Exercise Intensity:

It is obvious that taking a leisurely stroll won't burn as many calories as, say, squatting, benching, lifting heavy weights non-stop for an hour. How hard you work plays a huge, probably the most important role in how many calories you’re burning. Some calculators, especially those on cardio machines like treadmills and elliptical trainers, do take into account things like pace, resistance and incline, but using this information to estimate how much more you can eat or how much weight you’ll lose is tough because the formulas used to calculate exercise intensity and calories burned aren't 100% accurate.

Rather than rely solely on those numbers, you're better off learning how to monitor your intensity using a Target Heart Rate using a heart rate monitor in aerobic activities. Many monitors also show calories burned during your workout and you can use that number to compare different workouts and different intensity levels.

What exercise intensity burns the most calories and the most fat? While it may seem counterintuitve, the harder you train, the less fat you burn.

During low intensity exercise the majority of energy (kcals) comes from fat. As exercise intensity increases, you burn more calories, but the absolute amount of energy derived from fat becomes lower! Should you not train intensely, then? Well, depends on what you are aiming for. If getting rid of the spare tire is more of a priority for you, then yes, slow down and burn that fat away – don't forget to diet, too! However, I will not recommend this at all times. Even though a smaller percentage of the energy expenditure is coming from fat when you run faster and up-hill, for example, your metabolic rate goes through the roof and stays there forever! Why? Because with higher exercise intensity you also build more muscles, silly, even if training is aerobic. Therefore, expressing energy derived from fat as a percentage of energy expenditure without considering the total energy expenditure is misleading. If you want to burn more calories, high-intensity exercise seems like an obvious answer. The smashing part about this form of exercise is that higher intensities stimulate your metabolism far more after you stopped than lower intensity training.

That's right. The harder you work, the more calories you burn and continue to burn after you finished training. For example, if you train at low intensity (50% VO2 Max) for an hour or at higher intensity (75% VO2 Max) for 35 minutes and burn the same amount of calories, let's say 500 calories, the higher intensity bout will cause a significantly higher EPOC than the lower intensity bout (9.0 liters, 45 calories versus 4.8 liters, 24 calories). So, training harder may burn the same number of calories and save you some time. According to research, if you run at a steady pace (70% VO2 Max) for half an hour, your EPOC will be 34.5 calories. If you do an interval run which consists of 20 bouts of 1 minute short intense runs at 105% VO2 Max, your EPOC will be twice as much - 75 calories.

When it comes to lifting weights, you can predict your intensity by correlating the amount of weight lifted with the number of reps and sets, using Time Under Tension principle (how many seconds it takes you to complete one repetition or a set of exercise) and also how much time you rest inbetween sets. The researchers investigated the difference in EPOC between aerobic cycling (40 minutes at 80% Max HR), circuit training (4 sets, 8 exercises, 15 reps at 50% 1 RM) and heavy resistance training (3 sets, 8 exercises, 3-8 reps at 80-90% 1 RM). Heavy resistance training produced the greatest EPOC (53 calories), circuit training was not much lower (51 calories), but cycling showed to have the minimal burn after training (33.5 calories).

There is a rumour that high-volume training with lots of reps in each set burns more fat. Well, it is only a rumour which doesn't hold a lot of water, or bulk, for that matter. The researchers had college football players follow either a high-intensity/low-volume program or a lower-intensity/high-volume program for 10 weeks.

- The high-intensity program consisted of just 1 set of 6 - 10 reps per exercise taken to failure. This was followed by forced reps and then a static contraction where the working muscle was held in contraction for several seconds.
- The high-volume program consisted of 3 sets of 6 - 10 reps per exercise with no forced reps or static contractions.

The players following the high-intensity program had a decrease in bodyfat greater than 1%, while those following the high-volume program did not experience a significant bodyfat decrease. Given that the football players did not alter their diets during the program, only performed 1 set per exercise and no cardio was added, a 1% drop is pretty remarkable.

Training intensity has a larger impact on fat loss than training volume. The reason you see many bodybuilders doing reps after reps in their cutting season is not that they want to get a “pump” for muscle growth, burn fat or nuke additional calories, but because they are focusing on triggering the tiniest muscles with isolation exercises. These small muscle groups typically can't handle the heavy loads. If you want to lose weight than there are better ways to do this. Cardio burns fat, diet saves calories and high-intensity training requires a lot more energy to complete the workout in addition to an extra hefty chunk of calories essential for keeping and building new lean tissues. When you're in a cutting phase, focus on boosting the intensity of your training program by including techniques such as forced reps, static contractions, drop sets and supersets. This way you will still be able to lift heavy without working out too long.

“Just remember, when you’re over the hill, you pick up speed, “ (Charles M. Schultz).

Train hard and heavy and you will burn, baby, burn for days!

Workout Duration:

While it is obvious that the longer you train, the more calories you will burn during exercise at the same intensity, the duration of an exercise bout also affects how many calories you burn after the activity as well. In theory, the longer you train, the more calories you will continue burning afterwards. For example, if you run for 30 minutes, you will burn around 33 additional calories over the next 128 minutes. If you run for 45 minutes, you can expect to nuke 74.5 calories over 204 minutes after training. Get a bit more serious about your training and do continuous activity for an hour, you will flame your body reserves worth of 156 calories over 455 minutes of complete rest.

When researchers compared EPOC of two 25-minute sessions at 75% VO2 Max to a continuous bout of 50-minute continuous run at 75% VO2 Max, they found that the subjects expended twice as many calories after the shorter sessions than after a long workout - 15.5 calories versus 7 calories, respectively.

Exercing longer may burn more calories, but as you will fatigue, you won't be able to train as hard. This is especially true in lifting weights. Research has shown that after 45 – 60 minutes of training the ratio of muscle-building to muscle-breaking hormones goes down. At this point you will literally start eating up your lean tissues to supply energy for continuous activity. To add a calorie-burning element to your weight training while keeping the duration within an optimal range, limit rest periods to 30 - 45 seconds. Shorter recovery time may increase caloric burn by up to 50%, compared to a 3-minute rest period. However, you may not be as strong heading into your next set, and chances are that you may need to lower down the amount of weight lifted or decrease your reps, which means that your progress in the muscle gain will get a break. If the added calorie burn is worth it, go for it. If not – than stick with cardio and diet for fat loss and don't sacrifice the intensity of weight training for the sake of calories.

Real fitness fanatics may even amp up the calorie burn between sets by incorporating Super-sets or Drop-sets on weight-training days or perform their exercises non-stop in a circuit-style. In one study, standard resistance training (3 sets, 6 exercises, reps to exhaustion at 80% 1RM, 120 second rest) was compared to circuit resistance training (3 circuit sets, 6 exercises, 10-12 reps at 50% 1RM, 30 second rest). Total work volume of both programs was similar, however, circuit resistance training elicited a greater caloric burn after exercise than the standard workout (25 calories versus 13.5 calories).

Mechanical Exercise Efficiency:

You probably never thought that being good at an activity would mean burning fewer calories, but that’s exactly what happens when you exercise consistently. Think about the first time you lifted a dumbbell, pulled handles on a rowing machine, or tried a stair-stepper. It didn't feel right at first, you probably felt awkward, silly and it seemed to be a difficult task back then. When you were lifting the bar on a bench all you could think of is how to move your hands without shaking. Over time, the movement became so natural, you don’t have to think about it any more and now can lift heavy, extremely heavy weights with precise controlled movement. And you can cycle and run on a treadmill for almost an hour without stopping to catch your breath. This is terrific, but as your body became more efficient, you stopped wasting energy on unnecessary movements and are able to focus on progressing with resistance, increasing the intensity and duration. But this improved mechanical efficiency, a fancy term used to describe the improvement in specific movement, also leads to fewer calories burned.

In an exercise setting, efficiency is defined as the percentage of energy expended by the body that is converted to mechanical work (another form of energy).

Work Efficiency = Mechanical work / Chemical energy expended

How much fuel or how many calories the body needs to do any mechanical work depends on how much energy is expended by the body. This can be measured indirectly via oxygen consumption at sub maximal workloads. Regardless of what you do, you must generate ATP by chemically converting food energy, using a process that ultimately requires oxygen (hence the need for a big oxygen delivery capacity), while minimizing the production of lactic acid (high LT). Not all of the chemical energy in food is transferred to ATP and about 60% is lost as heat energy. This source of inefficiency is the same in everyone. If you could convert all 100% of energy trapped in foods you eat to ATP, you could say that your metabolism is extremely efficient, but it doesn't happen for reasons not yet known. It is just the way we are made. So, you convert oxygen consumption to a standard measure of energy like Joules, or Calories.

During exercise the ratio of inefficiency changes. Whether you cycle or run at sub-maximal intensity, your overall work efficiency may range between about 17% and 26%, with an average somewhere in the middle of that range. This is the estimated number from a number of different studies. In other words, for every 100 Calories of energy burned, you manage to convert around 20 Calories of that energy to useful work on the pedals when you cycle. Now, if your goal is to lose body fat during exercise, then I suppose being inefficient can actually be a good thing.

If your goal is to move your body faster than the other guy, or to be able to lift heavier weights, than being 25% efficient is way better than being 18% efficient! Even though you may waste less energy with greater mechanical efficiency, you can expend more calories because the intensity of your work can be a lot greater. Plus, by cutting down on awkward movements you can minimize the risk of getting an injury during training. And if you get injured, than you can ensure that your fat burn will be put on hold – no workouts until complete recovery is achieved.

Expect that after a month of repetitive routines your body will adjust its energy demands and will be starving for something new. Studies have shown that trained runners performed with 20% greater economy than other non-trained athletes. Make incremental increases to your weight loads, try new exercises, vary rest periods, experiment with advanced techniques like Plyometrics, change from barbells to dumbbells, just do something new, anything to keep your body guessing and improving.

The Weighty Issue of Body Mass:

Another irony with caloric burn is that the heavier you are, the more calories you burn. Doesn't make a lot of sense at first, because common knowledge assumes that overweight people usually burn fewer calories than fit people. But the reason for this is that fat people are usually less active. Heck, this is how they got fat after all – they move less and eat more. This also eventually lowers their metabolism and their bodies become less efficient at burning calories and more efficient at storing them. On the other hand, fit people burn extra calories before any can be stored as fat in the body.

If we consider the overall amount of calories burned at rest and during physical activity, heavier folks burn more for sure. For example, an 90-kg (200-lb) pound person can burn about 300 calories during 30 minutes of stairclimbing, while a 45-kg (100-lb) person burns about 150 calories doing the same thing. So, as you lose weight, your body expends less energy to move your body around, which means you’ll lose weight more slowly.

Also, as you lose weight with exercise and diet, the total amount of calories you burn at rest and during training goes down. New studies are revealing a reduction in the energy cost of the exercise itself after 2 months. So, even if you continue performing identical workloads, you will burn less. While it is easy to assume that the reason you start burning less is loss of body mass only, there is more to this paradox.

It is well known that neuroendocrine responses play a major role in regulating energy use during exercise. So, it is tempting to attribute this reduction in exercise energy expenditure to the hormonal adaptations to training. For example, plasma Norepinephrine and Epinephrine levels increase less in trained subjects than in untrained subjects during exercise performed at the same absolute intensity. Glucagon, Insulin, Growth Hormone, Testosterone, Cortisol and Adreno-corticotropic Hormone levels also increase less during exercise in trained subjects. This collective attenuation of hormonal output during exercise in trained subjects may contribute to the reduction in energy expenditure during exercise.

Genetics and Gender:

While you may be able to control many of the factors involved with weight loss or weight gain, there are some things which are completely out of control. If the diet or a training program is not working for you, to a degree you may blame this on your parents who have given you the genes and gender. Genes often determine how many calories you burn at rest, which muscle fiber types predominate at certain body parts, how you respond to different foods, how well your heart and lungs are working and how they adapt to exercise, whether you have long or short limbs, all of which can affect your metabolic efficiency and ability to burn calories, lose fat and gain muscles. Your genes even play a role in how well-defined, strong, big or dense your muscles can get, whether they are balanced and symetrical on the left and right sides of the body, and how much potential these have for being developed. Your body type also plays a role in which training program or which diet may be best for you.

Weight gain in response to overfeeding is also determined, in part, by inheritance. A study of seven pairs of identical twins revealed a dramatic difference in total weight loss and percentage of change in REE and NREE between the pairs, while all were on the same eating and workout regime.

Scientists at Johns Hopkins University have located a gene that contains the blueprint for a crucial bit of biological equipment called a Beta-3 Adrenergic receptor. It is part of the chemical machinery and is located mainly in fat or adipose tissue and is involved in the regulation of lipolysis (fat burn) and thermogenesis (energy expenditure). Some β3 agonists have demonstrated antidepressant effects in animal studies, suggesting it also has a role in the CNS.

Gender can also affect how many calories you can burn during exercise and at rest. Women usually have more body fat than men and their bodies respond differently to the same training styles, which can change the rate of weight loss. Still, even if you might inherit certain genes from your parents, your overall lifestyle, eating and exercise habits can make a huge difference. The only way to know what your body is really capable of is by experimenting. In any regard, unless you train, watch what you put in your mouth, as well as take a wise approach in managing stress, you can never say that the only reason your body is in an unhealthy state is because you were born this way.

So, all the above listed factors should be considered when you try to figure out how many calories you burn during exercise. If you're distracted by calculations that don't seem to add up, remember that they are only estimate numbers.

Bottom line? Either way, if you want to lose weight, it’s still better to exercise than sit on the couch. Exercise because it's terrific for your general health. There are thousands of greater reasons why you are always encouraged to train. For one thing, it makes you feel better about yourself, recharges your mind and body with energy, and no number of calories can buy this feeling. But to lose weight, though, you have to eat right as well.