 By Elena Voropay You probably have heard that muscle is the secret weapon in the war against fat. It’s natural, it grows without drugs or expensive supplements, it improves the look of your body, it gives you strength and more energy to do anything you want, and it literally makes you younger. Muscles are your reliable security guards protecting your sensitive body from the invasions of fat. However, there are a few myths surrounding the harvest of your gym hours. Many people may tell you that muscles burn thousands of calories every day. This sounds like a great motivator to make people exercise - the more muscle you have, the more calories you burn, even when you’re just sitting around.
But contrary to popular belief, your muscles are not the greatest calorie burners. Even though muscle is the largest tissue in the entire body composing up to 50-75% of all proteins in the human body, its estimated metabolic rate is much less than metabolic rate of your brain.
Basics Of Metabolism Stated simply, metabolism is a biochemical process. It combines nutrients with oxygen to release the energy your body needs to function. There are two phases to metabolism, anabolic and catabolic. The anabolic or constructive phase converts compounds from nutrients into substances the body can use.The catabolic or destructive phase reconverts the substances into simpler compounds to get the energy release needed to keep body cells going. Metabolism is measured in calories. The number of calories you burn in a day depends on several factors, including your basal metabolic rate (BMR), how much you exercise and the composition of your body tissues.
Muscle Tissue
You probably have heard that muscle is the secret weapon in the war against fat. It’s natural, it grows without drugs or expensive supplements, it improves the look of your body, it gives you strength and more energy to do anything you want, and it literally makes you younger, since the amount of muscle you have is one of the prime biomarkers of aging. And what's the one thing almost guaranteed to get attention and makes others green with envy? Toned, lean, shapely arms, legs, chest, back, shoulders and a washboard-looking stomach.
Muscles are your reliable security guards protecting your volnerable body from the invasions of fat. However, there are a few myths surrounding the harvest of your gym hours. Many people may tell you that muscles burn thousands of calories every day. This sounds like a great motivator to make people exercise - the more muscle you have, the more calories you burn, even when you’re just sitting around.
But contrary to popular belief, your muscles are not the greatest calorie burners. Even though muscle is the largest tissue in the entire body composing up to 50-75% of all proteins in the human body, its estimated metabolic rate is much less than metabolic rate of your brain. In fact, your muscles burn only 20 per cent of all energy, which is not that much at all. Scientific estimation of the metabolic rate of muscle is only about 10 to 15 kcal/kg per day. So, if you add five kilograms of lean mass, which is not an easy job to do as you may already know, you will burn only 75 more calories in 24 hours. Bummer! What a waste! You can just skip a cookie and remain the energy balance, right? Forget it.
Adding lean mass has long term benefits that other aerobic training or best supplements in the world can’t match. Muscle is considered “active tissue” because it requires energy to sustain itself by means other than caloric energy. First, even though 75 calories may not seem like a lot, these will add up to 24, 375 additional calories in a year! This means that without dieting or excessive training, you will naturally melt away around four kilograms of fat.
Another reason for muscle's high-octane power is their effect on various metabolic hormones, such as testosterone, growth hormone, insulin-like growth factor-1, insulin, leptin, thyroxin and other metabolic boosters to name a few. The more muscle tissue you have, the higher the levels of your energy-burning hormones will be. So, it is not just the lean tissue itself that consumes energy, but its effect on other systems in the body which can shift your metabolic engine into a high gear.
Fat Tissue
While lean tissues are the logs that keep the caloric fire raging, your fat is like a piece of paper and a match. It doesn't add much at all to your BMR. Fat, or adipose tissue, burns only five per cent of all calories. This is a common type of fat contained in white fat cells. They are designed to store energy for use in times of need. Chocked full of lipid droplets, these big cells accumulate under the skin and around internal organs. You need some adipose or fat tissue, which provides insulation and, by storing triglyceride, serves as an energy depot. But if you worry about too much white fat, you should. In excess, it doesn't do any good for your system.
Now you are about to reveal something truly astonishing – your body captures healthy fat as well. It is known as brown adipose tissue. Even though brown fat is still fat, it has the unique ability to generate heat and burn energy rather than conserving it.
Just like not all dietary fats are bad, not all body fats are bad either. Brown fat is actually a very healthy one and you want to carry as much of it as possible. Brown fat is a poorly understood tissue that seems to act the opposite of white fat, the ordinary stuff of bulging waistlines. The reason these fat cells are brown is because they are supplied with lots of blood and contain small lipid droplets tucked between tiny energy factories called mitochondria, the chemical structure which makes energy.
You can find this type of body tissue mainly around the neck and large blood vessels of the throat. In mice, brown fat cells are found throughout the body and are present during the entire life cycle. In humans, they are principally found in newborns, helping their tiny bodies generate heat. Brown fat cells largely disappear by adulthood, but their precursors still remain in the body, lodged in white-fat depots. Don't you wish it was the white fat that disapeared with ageing?
The more brown fat you have, the more heat you generate, and the more calories you burn. This tissue makes you feel warm and is important in controlling body temperature. If you have little brown fat, you've got a “freezer” type metabolism, are cold even in warm conditions, have lower thyroid gland production and your metabolism is quite slow. You also don’t burn foods well, and a lot of what you eat turns to ordinary white fat.
On the other hand, if you are blessed with a lot of brown fat, you have a “furnace” type metabolism. You burn body fuels so fast, that it seems like everything you eat just evaporates – no fat deposits! All the calories explode just like coals on a fire. The more you consume, the more you burn. How much brown fat do you have? This is a difficult question to answer because it is difficult to measure. When the fat is measured, you get the total number of all fat cells, but there is no way to separate the colours or the functions of each fat, brown and white. What is known is that white fat can mostly be found underneath your skin, but it also surrounds internal organs.
Genetics seems to play a role in how the body handles brown fat. Brown fat is activated by thyroid hormone and appears to respond to vitamin C, zinc, and copper supplementation. While you can't change your genetics yet, there is hope to find a way to alter human adult white fat cells into brown fat cells as a cure for obesity. Early researchers believe that the PRDM16 gene from which protein is manufactured at higher levels may be the key into unlocking the metabolic mystery. Experiments using mice fat cells are being conducted now.
Internal Organs
So, if muscles burn only 20 per cent of all calories at rest, fat adds up another five per cent, where do the 75 per cent of energy are blasted? In the rest of the body. The fascinating fact which most people don't know is that the heart, lungs, kidneys, brain and liver burn around 75-80 per cent of all calories. Now we are talking energy burn - these tissues have a metabolic rate that is 15-40 times greater than their equivalent weight of muscle and 50-100 times greater than fat tissue.
Body Size
Thinking that fat people are fat because their metabolism is slow is a good way to give them an excuse for their love of food. But it is just the opposite – big people have a much higher metabolism than small people because they not only have to carry a lot more weight when they move, but they also have a lot more muscle tissue and larger internal organs, the utmost metabolic burners. At complete rest, larger people need more energy to pump the blood around the body and to keep moving.
Plus, if these people eat a lot, their metabolism is higher because eating food actually burns calories. Bigger people also lose more calories simply from having a larger surface area. How can this be relevant to BMR? More energy is needed to maintain their body temperature because heat loss occurs through skin. The more skin you have – the more heat is lost. So, keeping the body temperature and constantly adjusting it to the environmental changes requires some extra give pushing resting metabolism way up.
Ok, you may forget all about body composition (as some fat and obese people actually do have a slow metabolism due to unbalanced hormones, higher appetites, etc.). Just consider body size. I mean, look at tall people. What is truly remarkable about body size is that the loss of body heat through larger skin surface area can be so tremendous, that the resting metabolic rate is often reported in kilocalories or kilocalories per square meter of body surface area per hour. So, the larger or taller you are - the higher your metabolic rate. Just as a big car uses more fuel, so a bigger person uses more energy. |
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