ABSTRACT

Dietary Restriction, Physical Activity, and the Propensity for Weight Loss ............ 72 Introduction ......................................................................................................... 72 The Role of Diet and Physical Activity in Weight Gain ..................................... 72 Dietary Restriction, Physical Activity, and Weight Loss .................................... 73

Dietary Restriction and Weight Loss .............................................................. 73 Physical Activity and Weight Loss ................................................................. 74 Diet-Induced and Physical Activity-Induced Weight Loss ............................. 74

The Impact of Dietary Restriction and Physical Activity on Energy Balance: Implications for the EfŠcacy of Weight Loss ...................................................... 75 Interindividual Variability in Biological and Behavioral Responses ..................77 Biological and Behavioral Compensation to Dietary Restriction and Physical Activity ................................................................................................. 78

Dietary Restriction and Metabolic Compensation ......................................... 78 Physical Activity and Metabolic Compensation............................................. 79 The Effect of Physical Activity on Energy Intake ..........................................80 Nonexercise Activity Thermogenesis ............................................................. 82 Dietary Restriction and Nonexercise Activity Thermogenesis ....................... 83 Physical Activity and Nonexercise Activity Thermogenesis .......................... 83

The Temporal ProŠle and Stability of Compensation: Is the Magnitude of Compensation Dose Dependent? ........................................................................84 Conclusions .........................................................................................................85

Substrate Metabolism, Weight Gain, and Appetite Control .....................................86 Introduction .........................................................................................................86 Postprandial TrafŠcking of Dietary Fat ...............................................................87 Substrate Metabolism as a Physiological Driver of Eating Behavior ................. 89 Conclusions .........................................................................................................93

References ................................................................................................................94

In many countries, governments and health agencies are strongly promoting physical activity (PA) as a means to prevent the accumulation of fatness that leads to weight gain and obesity. However, there is often a resistance to respond to health promotion initiatives. For example, in the UK, the chief medical ofŠcer has recently reported that 71 percent of women and 61 percent of men fail to carry out even the minimal amount of physical activity recommended in the government’s guidelines. Similarly, the Food Safety Agency has promoted reductions in the intake of fat, sugar, and salt but with very little impact on the pattern of consumption. Why is it that recommendations to improve health are so difŠcult to implement and produce the desired outcome?