In a world where people are surrounded by messages about what size and shape of our bodies is ‘best’ or what is the optimum fitness level, it is not surprising that society is also obsessed with what is good to eat, what is wrong to eat, and ‘getting it right’.


Dieting and exercise are touted as the means to not only become healthier but also happier. However, most people are not aware that diets are an ineffective means to achieve permanent weight loss. In addition, dieting has risks and can be damaging, leading to obsessive, unhealthy practices, further weight gain and potentially, diagnosable eating disorders. 


Put it simply; diets make most people fatter. Body weight is genetically determined in a similar way to height, and there are powerful homeostatic mechanisms that keep someone in a ‘set point range’. Dieting affects the brain’s mechanisms to regulate weight in complex ways. In the short term, weight loss will often occur rapidly and thereby serve as a  powerful motivator to keep restricting.  However, ‘success’ at dieting is short-lived because the body will start conserving energy by reducing its metabolic rate, which will lead to plateauing of weight despite continuing with food restriction. In the longer term weight suppression below the individual’s set point, increases the risk of binge eating and ultimately further weight gain as the body treats the weight loss as a threat and pushes to go back into ‘the safe zone’.  These mechanisms that occur with weight suppression are not easily reversed and anyone who has been on a lifetime of diets knows how it gets more and more challenging to lose weight and keep it off. This can create a vicious cycle leading to more extreme forms of disordered eating with negative physical and psychological consequences or even lead to the development of full-blown eating disorders. 


The neurobiology of eating disorders and dieting is complicated but the take-home message is simple. Extreme dieting is largely ineffective to achieve permanent weight loss and severe dieting has many negative effects on health and may trigger eating disorders in those who are genetically vulnerable, and for those already suffering from an eating disorder, dieting will make things much worse. 


It is important to recognise that even though dieting might be a conscious choice, eating disorders are not. Eating disorders are serious, life-threatening biological mental illnesses and most, if not all, eating disorders start with dieting or dietary restraint.


In essence, moderation is key. It is essential to eat a wide range of food with variety and flexibility including treat foods. It is helpful to eat mindfully, to drink less alcohol and to engage in enjoyable exercise, not just for weight loss purposes and  to develop a relationship to one’s body of acceptance and self care.


If you know of anyone who you are worried about, has obsessive rules regarding food and exercise or significant weight loss or weight fluctuations; be kind, compassionate but firm in supporting them to get help. Eating disorders are serious but recovery is possible. Early intervention and evidence-based treatments are essential.



Registered Psychotherapist, New Zealand Eating Disorders Clinic