Don’t Get Thin — Get Healthy!

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Body Fat and Exercise

Many people think that runners are healthy because of low body fat.  This is NOT true for some female runners. Without enough body fat they can’t make enough estrogen. Some no longer have menstrual periods. Others get bones as thin as those of an old crone because of low estrogen. Some don’t eat enough protein which is necessary to form the web-like matrix of bone cells on which calcium salts are deposited. Whereas moderate exercise helps calcium to be deposited in bone, excessive exercise has the opposite effect.

Other women complain that no matter how much they exercise, they can’t lose weight. I say they can’t use body fat because they aren’t eating enough fat.  In order to lose body fat, you need enough of the intrcellular enzymes that burn fat.  Otherwise you go into “starvation mode” where every calorie not used for immediate energy is turned into body fat.  In one study with mice that got no dietary fat, the enzymes that produce body fat from carbohydrates increased 26-fold(2600%). Conversely, if you eat enough fat, you increase fat-burning enzymes and then start to lose body fat. Moreover, dietary fat keeps you from feeling hungry because it slows down the emptying time of the stomach. You feel full longer also because fat causes the production of a satiety hormone in the brain.  A high carbohydrate makes you hungry every 2 hours as your insulin goes up and down.

Men runners can let their body fat decrease but this gives them less reserves for long distance running. Too many think that carbohydrates are the only source of energy for muscle movement, so try to keep the glycogen (animal starch) stores in liver and muscle high, then use sugars during a race. Don’t they know that fat is a better source of energy for muscle movement? The heart, which beats continually prefers fat. In my book I calculate that a man with 10% body fat has over 15 pounds of available fat that could produce 61,000 calories of energy, while glycogen stores can furnish between 1400 and 1800 calories. Instead of carbo-loading, racers should have a moderately high fat meal the night before a strenuous run and then replace lost body fat after the race along with enough protein to repair micro-tears in muscles.

One new friend demonstrates the value of body fat for long distance running. He is short and stocky, with a thin layer of fat evenly distributed over his muscular body.  He set a record on a 50 mile race, passing tall thin runners who constantly needed more sugar.  He had enough fat reserves that kept him going to win the race.

A typical runners’ diet of 80% carbohydrate and only 10 percent each of protein and fat is not healthy for the long term. Both fat and protein are necessary for the immune system.  Other authors say that runners have more colds than people who exercise more moderately since they don’t get the extra protein and fat they need to make constituents of the immune system.

No one should be afraid of eating fat. Thirty percent of your calories as healthy fat will keep you healthy along with moderate exercise.