INTRODUCTION
The majority of the adult population in the US
is overweight or obese.1 Consequently, effective
interventions are needed that will help people
achieve and maintain a healthier body weight.
Addressing the issue of body weight should start
with a basic understanding of energy balance.
Negative energy balance is required for weight
loss. People lose weight when energy expenditure
exceeds energy intake for a defined period
of time. Successful maintenance of weight loss
occurs when expenditure and intake are matched
at the reduced body weight for a continued
period of time. Although these states of energy
balance are clear, identifying the optimum strategies
to achieve them is challenging. In particular,
there is controversy about the relative importance
of changes in diet versus changes in physical
activity in body-weight management.