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Truth #1: Burning kilojoules in the gym is (almost) a waste of time
Sure, burning kilojoules is great. But the energy you expend in the gym isn’t as big a deal as those LED stats on the treadmill might make it seem. In fact, we all have three distinct types of “burns” that make up our metabolism. So why is it so hard to lose weight just by exercising? Why do you see so many overweight people in the gym? The answer is simple. Exercise and movement account for only 15 to 30% of your fat burn. Up to 85% of your kilojoule burn in a given day has nothing to do with moving your body. But that doesn’t mean you should skip the gym – you just need to know how to make exercise work for you. The fact is, exercise can play an important role in preparing muscle to conquer its greatest threat – fat, of course.
BASAL (RESTING) METABOLISM
Your basal metabolic rate, or BMR, accounts for 60 to 75% of your overall metabolism. Surprisingly, it represents the kilojoules you burn doing nothing at all. It’s fuelled by your heart beating, your lungs working to breathe and even your cells dividing.
This burn results from the thermic effect of food, or TEF. Simply digesting food
– converting carbohydrates to sugar and protein to amino acids – typically burns 10% of your daily kilojoules. You burn more kilojoules digesting protein than you do digesting carbohydrates and fat – about 25kJ for every 100 consumed, versus zero to 10 for carbs and fat.
EXERCISE AND MOVEMENTMETABOLISM
This part of your metabolism includes your gym workouts and other physical activities such as jogging or playing ball (called “exercise-activity thermogenesis” or EAT). It also includes your countless incidental movements throughout the day, like turning the pages of this magazine (“non-exercise-activity thermogenesis” or NEAT).
Truth #2: The fatter you get, the fatter you’ll get
Fat doesn’t just show up at your door one day, rent a room and live quietly alone with a couple of cats. Fat loves company. The more fat you open the door to, the harder you’ll find it to stop even more fat from inviting itself in. Here’s why. Your BMR – basal (resting) metabolic rate – accounts for the majority of the kilojoules you burn every day. It’s determined by a number of factors: your sex, age and height; your genes (most likely); and your body’s ratio of fat to muscle. The problem is, fat slows your kilojoule burn. Fat is lazy on a metabolic level: it burns barely any kilojoules at all. For your body to support a kilo of fat, it needs to burn about eight kilojoules a day. Muscle, on the other hand, is metabolically very active. At rest, half a kilo of skeletal muscle burns three times as many kilojoules every day just to sustain itself – and the more kilojoules you burn, the more body fat you tend to lose. That’s why fat hates muscle – because muscle is constantly burning it off. So fat actually fights back, trying to erode muscle. The main fat culprit is a nasty variety called visceral fat, which resides behind your abdominal muscles and surrounds your internal organs (the viscera). And visceral fat works its mischief by releasing a variety of substances collectively called adipokines. Adipokines include compounds that raise your risks of high blood pressure, diabetes, arterial inflammation and high blood sugar. Visceral fat also messes with an important hormone called adiponectin, which regulates metabolism. The more visceral fat you have, the less adiponectin your body releases and the slower your metabolism is. So fat literally begets more fat. In fact, a study in the Journal of Applied Physiology showed that the biologically active molecules that are released from
Truth #3: Weight training is the ultimate fat fighter
While muscle burns kilojoules, bigger muscle burns more kilojoules. That’s because the physical work you need to do to build and maintain added muscle can have a dramatic effect on your overall metabolism. Research shows that a single weight-training session can spike your kilojoule burn for up to 39 hours after you lift. (And remember, this doesn’t include the kilojoules you burn while you’re actually exercising. Think of those as a bonus.) And the long-term kilojoule burn you enjoy from building muscle does more than just eliminate extra weight. It specifically targets fat! A study conducted by dietician Dr Jeff S Volek, an exercise and nutrition researcher at the University of Connecticut, showed that people who built muscle lost almost 40% more fat on restricted-kilojoule diets than non-exercisers and aerobic
exercisers.Another reason weight training is the ultimate fat fighter: the more muscle you have, the better your body uses the nutrients you consume, and the less likely it is to store your food (even junk food) as fat. See, your muscles store energy (read: kilojoules) in the form of glycogen. When you exercise, your muscles call on that glycogen for fuel. After you exercise, your fat-storing hormones are subdued because your body wants to use incoming carbs to restore the glycogen depleted during your workout. So the carbs you eat after exercise are stored in your muscles, not in your spare tyre. But it gets better: if you complete a high-intensity workout (like the one below), your body will burn kilojoules at an advanced rate for hours afterwards, and it’ll be desperate for energy to keep your heart beating. Since the food you’re eating is being stored in your muscles, your body has to hunt for something else to burn. Guess what that is? Fat. Score another one for Team Muscle.