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by Eirini Christaki, Clinical Dietitian/Nutritionist

It is rather common to meet people who exercise regularly and spend many hours at the gym or doing other sports, and yet they complain about having excess body weight. This is not only the case for people who exercise to lose weight - it can also happen to athletes who want to lose weight to improve their body fat levels or to improve their cardiovascular fitness and athletic performance.

The reason why it seems strange that even athletes who spend a lot of time working out have trouble losing weight is that exercise and physical activity increases energy consumption, i.e. it burns calories. The energy expenditure of exercise is highly dependent on its intensity and duration.

Many studies have focused on studying the factors that prevent those who regularly exercise to lose weight. A recent publication that caused many reactions and led to many questions arising is that of Professor Dr. Ravussin from the Pennington Research Institute, who concluded that "for weight loss, physical activity is almost useless." This conclusion was based on two different effects of exercise: the stimulation of hunger due to the demand for energy, and the tendency of people to reward themselves by eating more or eating something delicious after a workout.

It seems that the most powerful factor determining calorie intake is the energy expenditure that results from a person's activities, according to Harvard Professor of Sociology of Health, Dr. Gortmaker.  The more energy one exerts, the more hungry they feel, and the more food they consume, so the harder it is for them to reduce their body weight.

But there is also a normal reaction in the body that reduces appetite for food after exercise. Following aerobic exercise (running, cycling, swimming, etc.), the hormone that regulates appetite decreases and in this way the appetite for food is reduced. This hormone is called grelin, and recent studies by the University of Massachusetts indicate that post-exercise appetite decreases mainly in men, whereas in women the concentration of the hormone is at normal levels, which makes them have a normal appetite. 

So, it is considered a given that diet is more effective than exercise in weight loss, but a balance of both is what can create 'miracle' weight loss.