[Strategies for successful weight reduction - focus on energy balance]

The prevalence of obesity and related health problems is increasing worldwide and also in Germany. It is well known that substantial and sustained weight loss is difficult to accomplish. Therefore, a variety of studies has been performed in order to specify causes for weight gain and create hypotheses for better treatment options. Key factors of this problem are an adaptation of energy metabolism, especially resting metabolic rate (RMR), non-exercise thermogenesis and diet induced thermogenesis. The extremely high failure rate (> 80%) to keep the reduced weight after successful weight loss is due to adaptation processes of the body to maintain body energy stores. This so called "adaptive thermogenesis" is defined as a smaller than predicted change of energy expenditure in response to changes in energy balance. Adaptive thermogenesis appears to be a major reason for weight regain. The foremost objective of weight-loss programs is the reduction in body fat. However, a concomitant decline in lean tissue can frequently be observed. Since lean body mass (LBM) represents a key determinant of RMR it follows that a decrease in lean tissue could counteract the progress of weight loss. Therefore, with respect to long-term effectiveness of weight reduction programs, the loss of fat mass while maintaining LBM and RMR seems desirable. In this paper we will discuss the mechanisms of adaptive thermogenesis and develop therapeutic strategies with respect to avoiding weight regain successful weight reduction.