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 calories 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 calorie burn. Fat is lazy on a metabolic level: It burns barely any calories at all. For your body to support a pound of fat, it needs to burn about 2 calories a day. Muscle, on the other hand, is metabolically very active. At rest, 1 pound of skeletal muscle burns three times as many calories every day just to sustain itself—and the more calories 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 visceral fat can actually degrade muscle quality--which, again, leads to more fat.
The solution? Bigger muscles. In addition to boosting your metabolic rate, muscle mass plays a key role in preventing more common (but no less deadly) conditions such as cardiovascular disease and diabetes. A survey of scientific literature published in the journal Circulation linked the loss of muscle mass to insulin resistance (the main marker of type 2 diabetes), elevated blood lipid levels, and increased body fat, especially visceral fat.
Truth #3: Weight training is the ultimate fat fighter
While muscle burns calories, bigger muscle burns more calories. That's because the physical work you need to do to build and maintain added muscle can have a dramatic effect on your overall metabolismResearch shows that a single weight-training session can spike your calorie burn for up to 39 hours after you lift. (And remember, this doesn't include the calories you burn while you're actually exercising. Think of those as a bonus.)
And the long-term calorie burn you enjoy from building muscle does more than just eliminate extra weight. It specifically targets fat! A study conducted by Jeff S. Volek, Ph.D., R.D., an exercise and nutrition researcher at the University of Connecticut, showed that people who built muscle lost almost 40 percent more fat on restricted-calorie diets than nonexercisers and aerobic exercisers.