There are two basic weight loss methods: diet and exercise. When used separately, it’s unclear how these methods affect appetite.
For this reason, a team of scientists examined how diet and exercise affect appetite. Their results were recently published in the American Journal of Clinical Nutrition.
Losing weight is hard. This is because your body doesn’t really want to lose weight, and uses several tricks to prevent this from happening.
One of them is to increase appetite and cravings to compensate for any lost weight.
However, previous studies suggest that losing weight by exercising may increase appetite and calorie intake less than dieting.
A group of scientists compared the effects of calorie depletion by dieting or exercising on appetite and calorie intake.
The purpose of this small, randomized, crossover study was to examine the effects of dieting or exercising on appetite, appetite hormones and food intake.
A total of 10 healthy, young and relatively fit men participated in the study.
The study started with a control period, during which the participants followed a standardized diet for three days.
The participants were then assigned to two groups in a random order:
- Dieting: During this three-day, calorie-reduced diet, the participants consumed 25% fewer calories than they needed to maintain stable body weight.
- Exercising: For three days, the participants did aerobic exercise. The amount of exercise was carefully adjusted so that the participants would burn 25% of the calories they needed to maintain stable body weight.
Since this trial had a crossover design, all participants exercised and dieted on different occasions, separated by a 2-week washout period.
At the beginning and end of each of the three study periods, the researchers measured appetite hormones (ghrelin and leptin). Calorie intake and appetite were measured only at the end of each of the three study periods.
Bottom Line: This was a randomized, crossover study comparing the effects of dieting and exercising on appetite and calorie intake.
Finding 1: Dieting Promoted Greater Calorie Intake
Calorie intake increased significantly more after dieting, compared to exercising.
It was measured at a 30-minute buffet at the end of each of the three study periods. The findings are shown in the chart below.
Bottom Line: Calorie intake was significantly higher at the end of the dieting period, compared to both the control and exercising.
Finding 2: Dieting Led to a Greater Increase in Appetite
Dieting led to greater subjective ratings of appetite, compared to exercising, as assessed with a visual analogue scale (VAS) questionnaire.
Specifically, the ratings of “desire to eat”, “hunger” and “prospective food consumption” (PFC) were significantly higher after dieting.
The chart below shows the differences between groups.
However, there were no significant differences in appetite hormones between groups.
Bottom Line: Subjective ratings of appetite were significantly higher after the dieting period, compared to exercising.
This study appears to have been well designed and implemented. However, a few limitations should be mentioned.
First, it was a small, pilot study with a limited statistical power. Second, the study was of short duration. The long-term effects of dieting and exercising may be different.
Finally, the participants were all young, relatively fit and healthy men. The results might not apply to other groups of people.
Bottom Line: The study’s main limitations were its small size and short duration.
Summary and Real-Life Application
This study showed that if you want to lose weight, dieting may increase appetite more than exercising, resulting in higher calorie intake to make up for the calorie deficit.
However, it would be difficult to imitate this study’s tightly controlled setting in a real-life situation.
Nevertheless, if you want to lose weight, exercise may make a difference.