Effects of Exercise, Diet, and a Combination of Exercise and Diet in Overweight and Obese Adults – A Meta-Analysis of the Data

ABSTRACT

The objective of the following meta-analysis was to determine what kind of treatment, or combination of treatments, has the greatest effect on weight loss in overweight and obese adults.

A systematic search was conducted of the available literature published between 1993 and 2006 that covered randomized controlled trials on overweight and obese subjects who underwent treatment consisting of physical exercise and/ or changes in diet. The scope of the search thus incorporated seven relevant databases.

Using 6,545 key word combinations, the electronic search yielded a total of 36,869 abstracts. 13 relevant studies with a total of 826 subjects (BMI > 25; 17 - 68 years of age) met the meta-analysis criteria. The courses of treatment included “diet (d)”, “physical exercise (pe)”, “diet and physical exercise (dpe)”, and “no intervention (ni)”. The results confirmed the hypothesis that the combined intervention “dpe” had the greatest effect with regard to weight loss. The single treatments “pe” and “d” also led to weight loss, with “d” having a significantly greater effect than “pe”.

The main reason for the small sample size of thirteen studies out of 36,819 was that the experimental design and/or procedures of most studies were inadequate. A common error was a failure to assign subjects randomly to the different treatment groups. The results of our meta-analysis indicate that a combination of diet and physical exercise is the best form of treatment to induce weight loss in overweight individuals in the first weeks, followed by physical exercise to maintain weight loss.