Despite the pressure we feel to look a certain way, or weigh a certain weight, many of us find that either our weight won't budge, we get stuck in weight loss plateaus, or that - even with successful weight loss - over time, our weight ends up right back where it started. This has led researchers to propose that our bodies might have a "set point" weight that the body strives to maintain despite our best efforts to achieve a change on the scale.
Way back in the "feast or famine" days, it certainly made sense for our bodies to be in survival mode regarding our weight, or energy stores, and to preserve those stores at all costs. We needed to be physiologically adapted to burning fewer calories at times when food intake was restricted. What about now, when we live in a culture where it could be feasting all the time? When we artificially reduce our intake through dieting, do physiological defense mechanisms still kick in to protect us from "starving" ourselves and support us to ultimately return to our pre-dieting weight? If fully 90 percent or more of dieters end up gaining weight back, mustn't there be something to this idea of a set-point?
One set-point theory proposed that a person's metabolism would adjust itself to maintain the weight at which it is comfortable, i.e., its set-point. Research indicates, however, that while metabolism may slow down during dieting, once calories are no longer being restricted, metabolic rates return to normal; thus a permanent metabolic slow-down is not likely to be the explanation behind weight regain. The most likely explanation for weight regain is that calorie intake is no longer being sufficiently restricted to maintain the weight loss. If this is the case, what causes us to increase our calories to the level that will return us to our higher body weights despite our desire to be thinner? Are other physiological mechanisms coming into play?
Recent research indicates that one of the appetite-controlling substances in our bodies, ghrelin (a hormone secreted in the stomach), may play a role in returning the body to a prior set-point weight after weight loss. Levels of ghrelin fall when subjects are fed and rise when subjects are fasting; studies have further shown that when subjects are injected with ghrelin, they experience significantly increased hunger and ingest 30 percent more calories. Studies have also shown that ghrelin levels rise in dieters who lose weight, suggesting that ghrelin may be provide a strong appetite stimulant and thus contribute to the increased calorie intake which leads to weight regain.
There appears to be evidence that our bodies may have built-in physiological mechanisms, with an assist from our food environments, to return to a prior-set point weight. The variables most strongly associated with successful weight maintenance are regular weigh-ins, keeping records, eating breakfast every day, and doing, on average, over 2600 calories of physical activity every week. While it may be challenging to "recalibrate" a weight set point, with some attention and effort in these areas, we are not necessarily destined to live at a particular weight.