Exercise may not stimulate appetite as previously thought. In fact, a British study, published in the journal Medicine & Science in Sports & Exercise, has shown the exact opposite, at least in the hours immediately following a workout. The study found that exercising before a meal reduced calorie intake by a third.
Two recent British studies counter claims that exercise makes people hungrier. Against all expectations, men and women who participated in two studies consumed fewer calories than "non-exercisers" when presented with a buffet meal. Both groups had the same calorie deficit, either through exercising or through restricting food intake.
For the first study, the team of researchers, led by Dr Stensel at Loughborough University in the UK, studied the hormonal, psychological and behavioral responses of 12 slim, healthy female students over a nine-hour period after restricting their calorie intake. The participants' levels of ghrelin — the hunger hormone — were found to have increased, while levels of peptide YY — a hunger-suppressing hormone — had dropped. As a result, this group of women consumed 944 calories on average at the buffet meal, compared with 660 calories for participants whose calorie deficit was created by running on a treadmill.
For the second study, the researchers asked 10 men and 10 women to run for 60 minutes. They were then monitored for seven hours afterwards. The scientists found that the more vigorous the workouts, the more hunger was suppressed.
The next step for the researchers is to investigate how different types of exercise and intensity levels affect appetite over a 24-hour period, rather than in the immediate short term. More research is also needed to determine whether the findings extend to overweight people and those who are less young, fit and healthy, and to establish whether these groups respond differently over a long-term period.