Is intermittent fasting more effective than dieting?

By Stephen Beech

Trendy intermittent fasting is more effective than a calorie-controlled diet for losing weight, suggests a new study.

People on a "4:3" intermittent fasting plan popular with celebrities showed "modestly greater" weight loss over 12 months than those on a daily caloric restriction diet, say American scientists.

The 4:3 plan involves restricting calorie intake for three days a week, then eating as you like for the other four days.

Celebrities who have spoken highly of intermittent fasting include Jennifer Aniston, Kourtney Kardashian and Halle Berry.

A clinical trial compared the effects of 4:3 intermittent fasting to daily caloric restriction on weight loss when combined with comprehensive behavioral support in adults who were overweight or obese.

The findings, published in the journal Annals of Internal Medicine, showed that 4:3 intermittent fasting resulted in modestly greater weight loss over 12 months.

Researchers from the University of Colorado School of Medicine randomly assigned 165 overweight adults to either 4:3 intermittent fasting or calorie restriction for 12 months to compare weight loss.

Participants in the 4:3 intermittent fasting group undertook a modified fast to produce an 80% energy restriction for three non-consecutive days per week.

On non-fast days, participants in the 4:3 intermittent fasting group did not have to restrict energy intake but were encouraged to make healthy food choices.

Participants in the calorie restriction group were prescribed a daily calorie goal designed to produce a 34.3% energy deficit.

All the participants were given free gym membership and encouraged to exercise for at least five hours per week.

As well as group-based behavioral support, participants received instruction in calorie counting and a guide to target dietary macronutrient content of 55% carbohydrates, 15% protein and 30% fat.

Study first author Professor Victoria Catenacci said: "At 12 months, participants in the 4:3 intermittent fasting group had a minus 7.6% change in body weight compared to minus 5% in the calorie restriction group."

She said 58% of those in the fasting group achieved weight loss of at least 5% at 12 months compared to 47% in the calorie restriction group.

Catenacci added: "Participants in the fasting group also achieved more favorable changes in cardiometabolic outcomes including systolic blood pressure, total and low-density lipoprotein cholesterol levels, and fasting glucose level."

The research team said their findings suggest that because fasting does not require participants to focus on counting calories and restricting food intake every single day, it may result in "greater adherence" and should be considered within the range of evidence-based dietary weight loss approaches.