Why diets don't work | Eating Disorders Victoria

Weight-loss and fad diets involve restricting food intake to levels which often leave a person constantly hungry and in some cases, lacking the necessary nutrients they need to maintain physical health and energy levels. The restrictive nature of dieting does not work, as fad diets do not provide a sustainable meal plan for the long term. Ninety-five percent of people who diet regain the weight and more within two years. 

Physical reasons that diets fail

Famine response

When food intake is reduced, bodies respond as if they are in famine or starvation situation. As a survival instinct, the body can adjust its metabolism or the amount of energy it uses to maintain bodily functions. Although it is very difficult to increase the body’s metabolism (increase the rate we burn energy), the body attempts to protect itself against famine by reducing the metabolic rate, which can happen within 48 hours of restricting either the type and/or the amount of food, and can decrease by as much as 40 per cent.


Leptin is a hormone produced by the fat cells in our bodies. It exists in the body in proportionate amounts to our weight. When body fat decreases, so do leptin levels. Bodies want to compensate for this loss in leptin and respond by increasing hunger urges and decreasing metabolism, which reduces the rate at which energy is burned.

Social and emotional reasons that diets fail

Food in social settings

Food is often associated with many social occasions and family gatherings, such as going out to dinner or a BBQ. People who are dieting often avoid social situations and family mealtimes, leading to feelings of isolation and a loss of support.

The diet/binge cycle

When food intake is restricted, a person experiences physical and emotional deprivation. This compels a person to eat, which commonly leads to overeating or bingeing. As a result, a person is likely to feel sensations of guilt and failure. This often becomes a cycle which is difficult to break and has devastating effects on a person’s self esteem, as demonstrated in the diagram below:


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