Intermittent fasting may be key to obese women losing weight

Fasting on a day-on, day-off basis may be the key to obese women losing weight, research by the University of Adelaide and South Australian Health and Medical Research Institute suggests.

The study of 88 women following a carefully controlled diet over 10 weeks found obese women lost more weight and improved their health by fasting intermittently.

The findings suggest intermittent fasting may be better for women trying to lose weight than trying to stick to a rigid diet.

The women had a breakfast of about 700 calories then fasted for the next 24 hours. The following day they ate as normal, then repeated the cycle.

The women had the breakfast-then-fast on Mondays, Wednesdays and Fridays, ate as normal on Tuesdays and Thursdays — and also ate as normal on weekends.

All participants of the study were women who were overweight or obese with a Body Mass Index (BMI) in the 25-40 range and aged between 35 and 70 years.

They followed a typical Australian diet consisting of 35 per cent fat, 15 per cent protein and 50 per cent carbohydrate.

The most successful participants lost 0.5 to 1kg per week for each week of the study.

Lead author Dr Amy Hutchison said obese women usually try to deal with their weight by continuously restricting their diet.

“Unfortunately, studies have shown that long-term adherence to a restricted diet is very challenging for people to follow, so this study looked at the impact of intermittent fasting on weight loss,” she said.

“Obese women who followed a diet in which they ate 70 per cent of their required energy intake and fasted intermittently lost the most weight.

“Other women in the study who either fasted intermittently without reducing their food intake, who reduced their food intake but did not fast, or did not restrict their diet at all, were not as successful in losing weight.”

The study also examined the effect of the different diets on the women’s health.

It found women who fasted intermittently as well as restricting their food improved their health more than those who only restricted their diet or only fasted intermittently.

“By adhering to a strict pattern of intermittent fasting and dieting, obese women have achieved significant weight loss and improvements in their health such as decreased markers for heart disease,” Dr Hutchison said.

Study supervisor Associate Professor Leonie Heilbronn said having the weekends “off” and enjoying a good breakfast before the fasting day began may have had a psychological impact which helped the women.

“The results did surprise us a little and there may have been a psychological impact which helped,” she said.

“There’s also potentially an appetite hormonal signal that we don’t understand yet that helps to maintain this diet better.

“This study is adding to evidence that intermittent fasting, at least in the short term, may provide better outcomes than daily continuous diet restriction for health and potentially for weight loss.

“While the study confirms that intermittent fasting is more effective than continuous diet restriction, the underlying signal for limiting people’s appetite, which could hold the key to triggering effective weight loss, requires further research.”

People interested in participating in planned future studies can email prefer@adelaide.edu.au

This story was reproduced with permission from The Advertiser.