The surprising discovery suggests that severe diets, such as those involving meal-replacement shakes, don’t necessarily exacerbate binge-eating behaviour.
The findings could provide additional treatment options for health professionals, who have generally hesitated to prescribe such extreme diets for obese patients due to concerns about potential adverse effects on eating behaviour.
“Intuitively, one would expect that such extreme diets would result in compensatory binge eating,” said lead author of the study Associate Professor Amanda Salis from the University of Sydney’s Charles Perkins Centre and Boden Institute of Obesity, Nutrition, Exercise & Eating Disorders.
“However, most studies showed that for people who were obese and binge eating before the diet, their binge eating actually declined during and just after the diet.
“For people who were obese and did not have any binge eating behaviour before the diet, some studies showed no change in binge eating, while other studies of lower quality showed a transient increase in binge eating, usually just after the diet, in 10 to 15 per cent of dieters.”
Published online in Obesity Reviews, the research involved a systematic review of clinical trials that measured binge eating before and after semi-starvation diets in people with obesity and people who did and did not have problems with bingeing before the diet.
“When clinically supervised, low or very low energy diets are an important treatment option for obesity. The results from this study show that these diets are not necessarily a trigger for binge eating, although eating behaviour should be monitored during their use,” Associate Professor Salis said.
The diets under investigation replaced meals and snacks with nutritionally balanced products, typically in the form of shakes. Such diets are called low energy diets when they deliver less than 5000 kilojoules per day, and very low energy diets when they deliver less than 3300 kilojoules per day. This is less than 20 to 50 per cent of the daily energy requirements of most people who are obese.
Associate Professor Salis emphasises that while these extreme diets come with the advantages of rapid weight loss and practicality, they are only recommended for people with a body mass index in the obese range (30 and over), or those with a body mass index of 27 or more who have risk factors for cardiovascular disease.
“An important caveat is that the long-term consequences of extreme diets on binge eating are unknown, as all but one of the studies we reviewed followed participants for less than 18 months,” she said.
“Also, all of the extreme diets under investigation were done within the context of carefully controlled clinical trials, which is completely different from ‘do it yourself’ starvation diets without clinical supervision, which have been linked to binge eating.”
To fill the gap in knowledge of the long-term effects of very low energy diets, Associate Professor Salis is seeking post-menopausal women from the Sydney metropolitan area for a clinical trial of the long-term (three-year) effects of semi-starvation versus conventional diets on binge eating behaviour in obesity. Women with or without binge eating behaviour are required.
For more information, contact Associate Professor Salis’ team on[email protected]