Promoting dieting for weight loss and weight maintenance is often criticized, because of the widely held belief that restricting food intake is the beginning of a slippery slope, leading to overeating and eating disorders.  However, a recent review by our department investigating the literature of dietary restraint shows that this may not be the case.

The idea that restricting food intake would lead to uncontrolled binge eating stems from laboratory studies from the 1970s.  Counter to expectations, people reporting that they were trying to lose weight by eating less (restrained eaters), ate more than unrestrained eaters when offered unhealthy but tasty food after being encouraged to break their diet by drinking a high calorie milkshake.  They also ate more than others after drinking alcohol or when they were upset.  These observations led to the belief that trying to control eating with one’s intellect rather than instinct can lead to less sensitivity to feelings of hunger and fullness, and cause people to overeat when their guard was lowered.  At the same time, research pinpointed dieting as a precursor of eating disorders, such as anorexia nervosa and bulimia nervosa, which further strengthened the lobby against the restriction of food intake.

However, closer examination of the research showed that the methods used to classify people as ‘restrained’ or ‘unrestrained’ eaters may have contributed to the findings.  For example, some of the questions asked to find out whether people restrict their food intake were actually assessing tendencies to eat in an uncontrolled way.  The links between restrictive eating and binge-eating were even less clear when considering the artificial lab setting in which participants were persuaded to break their diet, and then presented with an overwhelming amount of tasty food and told to eat as much as they wanted.

Furthermore, in the current environment, it may well be that a person eats less than desired, but still eats more than would be needed to keep weight stable.  Eating only one chocolate cake is better than eating two, but still, it can hardly be considered beneficial to your health!  This means that measuring food restriction alone may not be such a good indicator of successful weight management.  People who report restricting how much they eat may simply be the ones most likely to overeat.

Support for the positive effects of food restriction comes from real world examples.  In overweight individuals, where overeating is common, restricting food intake is related to lower body weight.  Findings from weight loss studies also show that the people doing best are the ones who vigilantly pay attention to what and how much they eat and don’t binge eat. In fact, evidence from studies with people suffering from binge eating has shown that gaining control over the amount of food eaten is related to fewer binge episodes.

So, how come the myth about the relationship between food restriction and disordered eating behaviour persists? The devil here may be in the detail of how people restrict their food intake. People who are following rigid, rule-based, ‘all-or-nothing’ eating are more likely to react with overeating and disordered eating once their rules are broken than people who take a more flexible approach, limiting rather than totally eliminating certain foods, and compensating for ‘off’ meals at the next meal or with an extra hour at the gym. Identifying oneself as a ‘dieter’ seems to be related to more rigid rules about eating and so may be undermining weight loss efforts.

The key to successful weight management may lie not in restraint per se, but in self-control. The ability to forego immediate rewards in pursuit of higher goals seems to be a skill that, once acquired, is not limited to successful weight management, but extends to other areas of life such as success at work, and better management of time and finances.  Although the capacity to control one’s desires seems to be partly inherited, the good news is that people can also be trained in self-control.  Learning how to control emotions, monitoring and evaluating one’s own  behaviour, setting goals, acquiring more beneficial problem-solving skills and thinking up action plans for resisting temptations have all been shown to enhance self-control.  The view that restraint is always ‘bad’ may need to be revised and the distinction between ‘rigid’ and ‘flexible’ restraint should be given more consideration.

The bottom line is that exercising a little restraint may not only benefit your weight but also your wallet, as long as it does not turn you into a rigid, miserly and overly concerned kill-joy.

Article Reference: Johnson, F., Pratt, M., Wardle, J. (2011). Dietary restraint and self-regulation in eating behavior. Int J Obes (Lond) doi:10.1038/ijo.2011.156.