I’ve never been hungrier than I was when I trained for Ironman Wisconsin in 2002. I trained hard for that race—up to 20 hours a week—and the harder I trained, the hungrier I became. I like to eat, so for a while I enjoyed the increased eating I needed to do in order to quiet my tummy. But eventually my appetite became an outright burden. I would eat a huge dinner at six o’clock in the evening and 90 minutes later I was hungry again. During the last few weeks before my taper it seemed as though I was eating pretty much nonstop between dinnertime and bedtime.
My experience is hardly unique. What’s true for me is true generally: as the volume or intensity of exercise increases, appetite and food intake tend to increase as well. Research has shown that chronic exercise increases the sensitivity of the body’s hormonal appetite signaling system, stimulates unconscious changes in food preferences, and alters the pleasure response to food in ways that significantly boost daily calorie intake. Studies in which overweight, sedentary men and women have been placed on exercise programs have found that for every 10 calories a person burns through exercise, three more food calories are consumed as a result of increased appetite.
Scientists refer to the elevation of food intake that follows increases in exercise as the “compensation effect”. The strength of the compensation effect varies between individuals. Some people do not eat more even when their exercise level increases drastically, while others have been known to gain weight while training for marathons and triathlons.
Obviously, this latter scenario is a problem. Body weight and body composition have strong effects on endurance performance. Each athlete has an optimal “racing weight”, which is usually at the lower end of his or her healthy weight range. The compensation effect often prevents athletes from reaching their racing weight and thereby hurts performance.
You can’t beat the compensation effect by ignoring your appetite and continuing to eat as much as you did when you were training less. Resisting strong hunger pangs day after day through weeks of hard training would require an inhuman amount of willpower. A more effective way to thwart the compensation effect is to focus on increasing the quality of your diet.
High-quality foods—namely, vegetables (including legumes), fruits, nuts and seeds, lean meats and fish, whole grains, and diary—are highly satiating. This means they satisfy hunger with fewer calories than low-quality foods: refined grains, fatty meats, sweets, and fried foods. The more you shift the balance of your diet away from low-quality foods and toward high-quality foods, the fewer calories will be required to fill you up.
So the next time an increase in training ratchets up your appetite, go ahead and eat more. But at the same time boost the overall quality of your diet. By doing so you will continue to get leaner, lighter, and faster without having to go hungry.