"Set point" theory is a newer way of describing this complex metabolic process. This theory applies to what our body "thinks" is normal and the set point is actually the amount of body fat our body tries to maintain. Obese people have a higher set point than trimmer ones. This may be related to the number of fat cells, which may in turn be tied to genetics and early eating patterns.

The set point theory suggests that our body works like a thermostat. When we diet and consume fewer calories, our body reacts as if a starvation crisis is upon us, with compensatory responses, such as lowering the BMR, the rate at which we burn calories, in an attempt to conserve calories and weight. The end result is that we can maintain the same weight on fewer calories. This theory makes sense, considering our long-term experiences with weight reduction.

Regular dieting, especially the low-calorie starvation diet, is met with ever greater difficulty in maintaining weight loss and often results in faster rebounds. As our weight goes up and down, our metabolism seems to slow, as it does with age, and it becomes harder and harder to lose weight. Once established, our personal set point and level of body fat are not easily influenced. Our set point, and thus our weight, might even go up. Our body really needs regular exercise and a long-term, steady, lower-calorie diet plan to adapt to a lower weight and better energy efficiency, or "turning our thermostat down."