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Exercise won't curb all those cravings

A study finds that obese women in particular may have to combine regular workouts with other methods to keep appetite levels in check.

June 23, 2008|Jeannine Stein | Times Staff Writer

AFTER AN intense round of exercise, many people simply do not want food. For them, a workout is a natural appetite suppressant.

But for others -- particularly the obese -- that same workout may not dim their hunger pangs at all. A recent study found that obese women don't experience the same type of hunger numbing after exercise that their lean counterparts do.

The study, presented recently at the Endocrine Society's annual meeting in San Francisco, followed nine lean women and 10 obese women who were given a weight-maintenance diet. Each was asked to be sedentary for one day, do two bouts of moderate exercise on another day, and two bouts of intense exercise on a third day (exercise was done in the morning and the afternoon).

Subjects were asked to rate their hunger levels throughout the day and had their leptin levels tested. Leptin is a hormone produced by fat cells that works as an appetite suppressant. Levels are generally lower in thin people and higher in the obese; some studies have shown that obese people may have a resistance to the hormone and are not able to feel its effects as strongly.

At times of peak hunger, the lean women reported being a little hungrier than the obese women -- they ranked it 80% out of 100%, versus 65% for the obese women. The lean women also reported feeling a rise in hunger during the first bout of both moderate and intense exercise, but none during the second. Hunger in the obese women, however, didn't abate at all during either type of exercise.

Leptin levels were lower for lean women than obese women at the start of the study, dropped during exercise and stayed low throughout the day. Levels in obese women only showed reduction during moderate exercise, not during intense levels.

"These hormones don't seem to be strongly linked to appetite control during exercise," says Katarina Borer, kinesiology professor at the University of Michigan and lead author of the study. "The bottom line is that obese women don't show appetite suppression during exercise, and may need to exercise a conscious effort to eat less and control their appetites."

The study results may help explain why exercise alone doesn't work for weight loss -- that calorie restriction plays a key role as well. "We all tend to be opportunists when we eat more than we need to after exercising," Borer says.

Even if exercise doesn't make hunger pangs go away, there are ways to control appetite, says Felicia Stoler, a greater New York-based exercise physiologist and registered dietitian. For afternoon and evening exercisers, she recommends eating a nourishing snack before a workout that consists of carbohydrates, proteins and some healthful fat, and includes fiber -- such as nuts, a little bit of cheese, dried fruit or yogurt. The snack can be after the workout too, before dinner. Morning workouts should also be preceded by a snack to avoid exercising on an empty stomach. Staying hydrated is also important, she adds, as thirst can sometimes feel like hunger.

"If you don't have satiety cues," says Stoler, a fellow of the American College of Sports Medicine, "that can make things difficult when you're trying to have some semblance of self-control and really understand the limits of what your caloric intake should be for the day."

However, she adds, people should never expect exercise to dull their appetite. "The reason for exercise is not to suppress hunger. It helps to improve cardiac health, lower blood pressure and increase muscle mass. But don't rely on it for satiety."

Keeping food in the car can stave off those impulsive runs to the drive-through. Stoler also suggests not thinking of food as a reward for working out: "You think, 'I worked really hard, I'm going to eat a chocolate doughnut.' Exercise so you can eat it once in a while, not every day. There are other ways to reward yourself than with food."


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