Dieting approaches may not be effective for weight loss, according to research

Weight control attempts by middle-aged New Zealand women are not linked with change in weight three years later, according to new University of Otago research.

The research team, Dr Sook Ling Leong, Dr Jill Haszard and Associate Professor Caroline Horwath from the Department of Human Nutrition, and Andrew Gray from Preventive and Social Medicine, investigated the relationship between self-reported weight control practices and weight change three years later in more than 1,600 New Zealand women aged between 40 and 50. Women in this age bracket are known to be at high risk of weight gain.

Study first author Dr Leong says that after adjusting for other factors including age, ethnicity, smoking, physical activity and menopause status, the researchers found that weight control methods—whether healthy or unhealthy ones—were ineffective in helping women to lose weight over a three-year period.

Dr Leong says that women who reported trying to control their weight were more likely to engage in several healthy eating behaviours than women not attempting weight control. However, they showed no differences in their frequency of consumption of most of the energy-dense foods surveyed such as burgers, deep-fried fish, hot chips, ice cream and lollies.

"Results from the study suggested that women may not be employing healthy changes in food habits frequently enough or that serving sizes of energy-dense foods may not have been reduced sufficiently—both of which could undermine weight control efforts," she says.

Further analyses showed that women who at the start of the study reported trying to lose weight were found three years later to have a reduction in the degree to which they ate in response to their body's hunger and fullness signals (i.e. intuitive eating scores) and an increased likelihood of binge eating.

The researchers write that the results suggest "dieting to lose weight may reduce women's ability to recognise hunger and fullness signals and effectively regulate eating behaviours, which may in turn trigger episodes of binge eating and therefore weight regain".

Associate Professor Horwath and her team are currently testing "non-dieting" interventions that focus on enabling women to break free from chronic dieting and developing skills to eat in accordance with hunger and fullness cues.

"Our interventions include listening to their feelings of hunger and fullness, rather than focusing on weight loss. Such non-dieting approaches are gaining increasing interest from dietitians, as the traditional dieting approach of restricting both calories and food types has shown poor results in achieving long-term weight loss," Associate Professor Horwath says.