Alternate day fasting might not be the best way to lose weight. [Photo: Bigstock]

Is alternate-day fasting more effective for weight loss?

8 May, 2017

Natural Health News — When it comes to weight loss fasting – in a variety of different forms – is definitely the latest trend.

While many claim success using this method, a new study suggests it might not be the best way to go.

The study, published in the journal JAMA Internal Medicine, looked at whether alternate-day fasting was more effective for weight loss and weight maintenance compared with daily calorie restriction. The randomized clinical trial, conducted by researchers from the University of Illinois at Chicago, followed 100 metabolically healthy obese adults for a year. They were placed into three groups: an alternate-day fasting group, a calorie-restriction group, and a no-intervention control group.

Those in the alternate-fasting group consumed 25% of their typical calorie intake (about 500 calories) on fasting days, and 125% of their typical intake on ‘feasting’ days. The calorie-restriction group (on a traditional diet) consumed 75% of their typical caloric intake every day.

After analysing the data the authors discovered that, contrary to expectations, alternate-day fasting diet was not superior to the daily calorie-restriction diet with regard to adherence, weight loss, weight maintenance, or improvement in risk indicators for cardiovascular disease including blood pressure, cholesterol and glucose levels.

What you need to know

» Alternate day fasting has become a popular way to lose weight and maintain weight loss.

» Most studies have suggested it is effective – though these have been mostly short term studies of a few months.

» A new longer-term study, over a year, suggests that alternate day fasting may not be any more effective than daily calorie restriction – and in fact may be harder for some to follow.

Both groups did lose weight, with a 6% loss for the alternate-day fasting group and a 5.3% loss for the daily calorie-restriction group. As far as regaining the weight, the researchers determined that, after 6 months of follow up, there was not a significant difference between the two groups.

Dissatisfied dieters

“Alternate-day fasting has been promoted as a potentially superior alternative to daily calorie restriction under the assumption that it is easier to restrict calories every other day,” the researchers reported. “However, our data from food records, doubly labelled water, and regular weigh-ins indicate that this assumption is not the case.”

Instead they found instead was that the dropout rate in the alternate-day fasting group was higher than that of the daily calorie-restriction group (38% vs 29% – and 26% in the control group). More participants in the alternate-day fasting group also withdrew due to dissatisfaction with diet, compared with those in the daily calorie-restriction group. Some, in the alternate-day fasting group converted their diet into de facto calorie restriction as the trial progressed.

The authors concluded that “taken together, these findings suggest that alternate-day fasting may be less sustainable in the long term, compared with daily calorie restriction, for most obese individuals.”

Still many unknowns

Research into fasting is not plentiful – it’s only in the last couple of decades that it has been on scientists’ radar.

Also most studies have only followed the participants for two or three months. The current study followed participants for a year – the longest human fasting trial to date – which included 6 months of weight loss and 6 months of maintenance. Even so this still may not be long enough to demonstrate conclusively how well each approach to weight loss works.

The results according to co-author Krista Varady, a professor of nutrition at the University of Illinois Urbana-Champaign, don’t necessarily indicate that alternate day fasting doesn’t work but just that it may not be much more effective than normal dieting. Also it does not tell us, why, for example, some people get on really well with fasting while others don’t. Personality types, the amount of stress a person is under and in particular pre-existing conditions like diabetes or pre-diabetes, may be influential. Varaday and her colleagues do plan to look at fasting diets in contexts like this in future research, so watch this space.