Can intermittent fasting help you lose weight?

Overweight women who ate fewer calories and fasted three days a week lost more weight and had better cardiometabolic markers than women who only reduced their calorie intake or just fasted, or in a small randomized 8-week study did not both did not.

"Obese women who followed a diet where they consumed 70% of their energy needs and fasted occasionally lost the most weight," said lead author Amy T. Hutchison, postdoctoral fellow at Adelaide Medical School, University. of Adelaide, Australia, said. in a statement from their university.

'Other women in the study,' she noted, 'who fasted occasionally without reducing their food intake, who reduced their food intake but did not fast, or did not limit their diet at all, were not as effective to lose weight. '

In this group of nearly 90 overweight or obese middle-aged and older women randomized to the four different strategies, the most successful participants lost about 0.5 to 1 kg per week.

"This study is further evidence that occasional fasting can yield better results, at least in the short term, than continuous daily dietary restrictions on health and possible weight loss," says senior author Leonie Heilbronn, PhD, associate professor at the University of Adelaide and South Australian Health and Medical Records Institute.

Dorothy D. Sears, PhD, associate professor of medicine at the University of California, San Diego, who contributed to a review of the metabolic effects of alternating fasting, said: 'This is another ... study of intermittent fasting fast indicating one advantage. However, she pointed out that it was 'small and powerless'.

Researchers agree that more research is needed and acknowledge that these results cannot be passed on to a longer intervention or other populations.

"While the study confirms that intermittent fasting is more effective than continuous dietary restriction, the underlying signal needed to reduce appetite, which may be the key to effective weight loss, needs further research," Heilbronn said.

Intermittent fasting, reduced calories, or both?

A continuous calorie diet remains 'the cornerstone of the lifestyle to reduce the risk of type 2 diabetes and cardiovascular disease', Hutchison and colleagues write in their article.

However, intermittent fasting may be a better strategy as it makes it difficult for people to stick to a low calorie eating plan.

However, the results of temporary fasting studies are mixed, some showing greater weight loss and improved metabolic markers, while others report weight loss but no improvement in metabolic markers.

It is noteworthy that five studies lasting from 2 to 12 months have shown that intermittent fasting and a decrease in calorie intake led to similar decreases in body weight and cardiovascular risk markers, write Hutchison and colleagues.

However, it was not clear whether a 'metabolic switch' between food intake and fasting rather than weight loss could underlie the health benefits of intermittent fasting.

Therefore, they conducted a randomized, controlled trial with obesity in obese women to compare how intermittent versus continuous food intake at two energy levels affects peripheral insulin sensitivity, weight, body composition and cardiometabolic markers, and to investigate acute metabolic changes when participating "fed" to a "fasted" state

After a two-week survey, 88 women aged 35 to 70 years with a body mass index of 25 to 42 kg / m2, who did not have diabetes and were not physically active, were randomized to four groups for 8 weeks:

No reduced calories or no fasting (100% of the calories needed to maintain the basic weight), control group (12 women);

Intermittent fasting and reduced calories (70% of the calories needed to maintain the basic weight) (26 women);

Intermittent fasting, no reduced calories (25 women);

Constantly reduced calories (70%), no fasting (25 women).

In the fasting groups, the participants fasted on three consecutive days of the week from 08:00 to 08:00. , chewing gum or peppermint) and ml of a 20-calorie sauce.

All foods were delivered to the women every 2 weeks, and their diet had the same nutritional composition (35% fat, 15% protein and 50% carbohydrates).

Low calorie fasting and best metabolic results

Insulin sensitivity, weight, body composition and plasma markers were measured at baseline and 8 weeks after a “fed” day (after 12 hours of fasting, at night for all participants) and after a 24 hour fast (in the fasting groups).

Women in the intermittent fasting and calorie group had greater weight loss, fat mass, lipoprotein cholesterol and unesterified fatty acids in total and low density compared to women in the intermittent fasting and calorie reduction group (all P ≤) .05).

"Intermittent fasting was more effective than dietary restriction in reducing body weight and improving metabolic health when prescribed with a similar energy deficiency, but it did not affect insulin sensitivity otherwise, as determined by hyperinsulinemic-euglycemic stress," said Hutchison and colleagues .

And when intermittent fasting without energy restriction was prescribed, there was a transient increase in diabetes risk markers "and no general improvements in metabolic parameters compared to other groups, despite a small amount of weight loss".

"This study shows that intermittent fasting approaches with repeated 24-hour fasting improve metabolic health when there is an energy deficiency, but not when there is an energy balance," they conclude.