Many people believe that exercise is required to cause weight loss. This is based on the fallacy that it is the quantity of food we eat that determines weight gain. The assumption is that because weight gain is caused by too much food, increasing the amount of energy that is burnt through exercise will tip the energy balance equation towards deficit, and this will cause weight loss. Often along with exercise, low energy diets are consumed for the same reason. The reality however that it is not how much we eat, but what we eat that determines body weight changes. Data clearly shows that eating low quality foods, particularly refined and processed foods is the cause of weight gain. Such a diet is typified by the foods in the typical Western diet. In contrast eating high quality diets such as traditional diets causes weight loss without the need for energy restriction. This contention is supported by a wealth of data showing that exercise alone does not cause weight loss in overweight individuals.
For example, in one study1 obese men and women were prescribed an exercise regimen which was designed to expend roughly 500 kcal per session. This exercise was performed 5 times per week and involved endurance style exercise at 70 % of maximum heart rate. The mean body weight loss after 12 weeks was 3.2 kg and differed significantly from the baseline body weight. However, there was a large variation in the weight changes seen in the subject, with body weight change varying from a loss of 14.7 kg to a gain of 2.7 kg. Fat mass changes were also variable with the largest loss of body fat being 10.2 kg and the largest gain in body fat being 1.7 kg. Therefore this exercise regiment was not consistent in the results it produced for the subjects. Such a pattern of variable results often indicates that some other factor is modifying or influencing the result. Therefore the authors investigated confounding variables that might be influencing the body weight and body fat changes.
Subsequent analysis was performed on the subjects by categorising them as responders or non-responders. The authors then analysed the diets of the subjects to understand if dietary changes may be responsible for the body composition changes. The results of this analysis showed that the responder increased their fruit and vegetable intake during the 12 week study, whereas the non-responders decreased their fruit and vegetable intake during the same time period. Therefore dietary changes occurred that could explain the body weight changes. Had the authors not performed this analysis, it could have been concluded that exercise was beneficial to weight loss by just using the mean (-3.2 kg) weight loss value. However, this study shows once again that dietary changes are the driver of weight changes, and not exercise. Had a control group been included that increased their fruit and vegetable intake, but not performed any exercise, it is my assertion that this group would also have lost weight and body fat.
RdB
