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Intermittent fasting

HELENA study: intermittent fasting no better vs conventional diets

Although the HELENA study does not confirm the expectations placed in intermittent fasting, it also shows that this method is not less beneficial than conventional weight loss diets
The investigators did not find any difference between the two dieting methods in any other metabolic values that were analysed or biomarkers and gene activities under investigation

Intermittent fasting (intermittent calorie restriction, ICR) leads to weight loss and promotes health, however, it is not superior to conventional calorie restriction (CCR) diets, according to the outcomes from the HELENA study - the largest investigation on intermittent fasting to date. Researchers from the German Cancer Research Center (DKFZ) and Heidelberg University Hospital concluded that there are many paths leading to a healthier weight and recommended that individuals find a diet plan that fits them best. The outcomes were reported in the paper, ‘Effects of intermittent and continuous calorie restriction on body weight and metabolism over 50 wk: a randomized controlled trial’, and published in The American Journal of Clinical Nutrition.

Intermittent fasting, also known as 16:8 diet or 5:2 diet, is currently popular, with advocates claiming it results in weight loss without yo-yo effect, as well as sustained changes in metabolism and resulting health benefits. However, the German Nutrition Society (DGE) has warned that intermittent fasting is not suitable for long-term weight regulation. In addition, according to DGE, there is not enough scientific evidence on the long-term effects of this dieting method.

"There are only a few smaller studies on intermittent fasting so far, but they have come up with strikingly positive effects for metabolic health," said Dr Ruth Schübel from DKFZ. "This made us curious and we intended to find out whether these effects can also be proven in a larger patient group and over a prolonged period."

In collaboration with a team of DKFZ researchers and scientists from Heidelberg University Hospital, Schübel examined 150 overweight and obese study participants (BMI≥25 to <40, 50% women, aged 35–65), over one year as part of the HELENA study. At the start of the study, they were randomly classified in three groups: one-third followed a conventional calorie restriction diet that reduced daily calorie intake by 20 percent. The second group (ICR) kept to a 5:2 dietary plan that also saved 20 percent of calorie intake over the whole week. The control group followed no specific diet plan but was advised, like all other participants, to eat a well-balanced diet as recommended by DGE. Following the actual dieting phase, the investigators documented the participants' weight and health status for another 38 weeks.

"In order to keep the new body weight, people must also permanently switch to a balanced diet following DGE recommendations.”

Loge relative weight change over the intervention phase was −7.1% ± 0.7% (mean ± SEM) with ICR, −5.2% ± 0.6% with CCR, and −3.3% ± 0.6% with the control regimen (p=< 0.001, PICR vs. CCR =0.053). Despite slightly greater weight loss with ICR than with CCR, there were no significant differences between the groups in the expression of 82 pre-selected genes in adipose tissue implicated in pathways linking obesity to chronic diseases.

At the final follow-up assessment (week 50), weight loss was −5.2% ± 1.2% with ICR, −4.9% ± 1.1% with CCR, and −1.7% ± 0.8% with the control regimen (p=0.01, PICR vs. CCR =0.89). The researchers noted that these effects were paralleled by proportional changes in visceral and subcutaneous adipose tissue volumes. There were no significant differences between ICR and CCR regarding various circulating metabolic biomarkers.

"In participants of both group, body weight and, along with it, visceral fat, or unhealthy belly fat, were lost and extra fat in the liver reduced," added Schübel.

The changes in body weight distribution in the study participants were exactly determined using special MRT imaging executed by Johanna Nattenmüller at Heidelberg University Hospital. Those who reduced their body weight by only five percent, lost about 20 percent of dangerous visceral fat and more than a third of fat in the liver, no matter which dietary method they have used. The investigators did not find any difference between the two dieting methods in any other metabolic values that were analysed or biomarkers and gene activities under investigation.

Tilman Kühn

Although the HELENA study does not confirm the expectations placed in intermittent fasting, it also shows that this method is not less beneficial than conventional weight loss diets.

"In addition, for some people it seems to be easier to be very disciplined on two days instead of counting calories and limiting food every day," explained Dr Tilman Kühn, principal investigator of the trial. "But in order to keep the new body weight, people must also permanently switch to a balanced diet following DGE recommendations.”

According to Kühn, the study results show that it is not primarily the dietary method that matters but that it is more important to decide on a method and then follow through with it.

"The same evidence is also suggested in a current study comparing low-carb and low-fat diets, that is, reducing carbohydrates versus reducing fat intake while otherwise having a balanced diet," said Kühn

The researchers concluded that body and health will benefit from weight loss in any case, as long as it is achieved by a reliable dieting method and on the basis of a well-balanced diet.

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