Two-week on, two-week off diet 'is the best way to lose weight because it stops your metabolism slowing down'

It could be the perfect solution for those who want to lose weight but lack willpower.

People who diet two-weeks on, two-weeks off lose more weight than those who deprive themselves week in, week out, a study found.

It is thought that the on-off approach stops the body from finding ways to compensate for the lack of calories and so ensures the pounds keep falling off.

 

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Do both: Studies show that mixing up your diet with weeks or days with normal, balanced eating habits, means losing more weight

Researcher Nuala Byrne followed the fortunes of 36 obese men as they tried to lose weight.

Half dieted continuously for 16 weeks, cutting their calories by a third. The others followed a pattern in which they dieted for a fortnight, then had two weeks off, then dieted again.

Although their programme lasted 30 weeks overall, just 16 weeks were spent dieting, the same as for the first group.

Those on the on-off diet lost more than two stone on average – 55 per cent more than the men who dieted non-stop, the International Congress on Obesity heard.

What is more, their extra weight loss couldn’t be explained away by their programme lasting longer, as they shed very little weight during the rest periods.

 

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Have it all: The on-off approach stops the body from finding ways to compensate for the lack of calories and keeps the metabolism going

Professor Byrne believes they did better because their bodies didn’t switch to an energy-conserving survival mode.

Backing this up, she showed that resting metabolic rate, the amount of energy the body spends when ticking over, dropped less in the men on the on-off diet. This should have helped stop their weight loss from levelling off.

Professor Byrne, of the Bond Institute of Health and Sport in Queensland, also plans to check if intermittent dieting stops the body from trying to claw back the missed calories in other ways, such as by increasing appetite.

 

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See results: On-off diets, such as 5:2 work

She said: ‘Given that long-term weight loss is a challenge we are interested in finding ways to overcome the biological and behavioural impediments to losing weight.

‘The results from our study are encouraging as they suggest providing “rest periods” can overcome some of the compensatory biological factors which reduce weight loss efficiency during continuous dieting.’

She added that the highly-popular 5:2 diet, in which slimmers drastically cut their calorie intake two days a week may have the same effect. However, there is a risk that those following the 5.2 diet will overeat on normal days because they are free to eat what they want.

In contrast, her diet is less extreme and contains instructions for both the ‘on’ and ‘off’ phases.

Professor Byrne said that she believes her diet plan ‘has the potential to appeal to almost anyone’.

But Carrie Ruxton, an independent dietician, questioned whether slimmers will want to go back to depriving themselves after having a fortnight off.

Dr Ruxton, spokesman for the Health Supplements Information Service also warned that many British adults are already low in vital vitamins and minerals, such as iron, calcium and vitamin D, and dieting can make it worse.

She said that while she is keen for people to lose weight, they need to get into good habits that they can maintain in years to come. She recommends thinking about vices, such as alcohol and chocolate, and cutting down on them, to get results.

Last year a survey revealed that slimmers often consume more than half their weekly calorie intake from Friday night to Sunday.

Away from the daily routine at work that helps them keep control of what they eat, they are snacking and drinking their way to an astonishing 10,000 calories, the study found.

Almost three-quarters of people trying to lose weight admitted over-indulging at the weekend, according to a poll, from diet firm Forza Supplements.