Tracking down the Yo-Yo effect – science researches

The topic of the yo-yo effect is attracting increasing attention in science. The term describes the phenomenon of unwanted and rapid weight gain after dieting. Researchers are investigating the causes and effects of this demotivating and health-endangering effect. The goal is to find oTracking down the yo-yo effect - science researches ut how the counterproductive weight ping-pong can be avoided. Various studies are taking different approaches. Our medical team summarises two of them for you.

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Over 300 million people suffer from obesity. This corresponds to 44 percent of the adult population worldwide. Those affected are confronted with mental stress and physical consequences such as cardiovascular diseases or diabetes. The yo-yo effect puts a spanner in the works of many who want to lose weight, and there is no long-term success. But there is more to it than a lack of eating discipline or willpower, as observations now show.

Study #1: A glyx game: Protein-rich diet prevents Yo-Yo effect

In 2010, as part of the so-called Diogenes Study, an international research team followed 772 families in various EU countries to find out which dietary factors play a role in weight gain1.

The results, published in the New England Journal of Medicine ↗ , show: Integrating lots of protein into one's diet increases the chances of preventing the yo-yo effect.

Study details

The large-scale diet study followed 772 families with 938 overweight adults and 827 children, with about 72 percent completing the study.

At the beginning, the participants adhered to a diet for eight weeks, during which they lost an average of 11 kg. Families were then randomly assigned to one of five diets, which they followed for a period of six months:

Diet Details
Diet 1 Diet with increased protein content (25 percent protein content) and low glycaemic index (GI)*.
Diet 2 Diet with increased protein content and high GI
Diet 3 Diet with low protein content (13 per cent protein content) and low GI
Diet 4 Low protein, high GI diet
Diet 5 Control group, which followed the existing dietary recommendations of the corresponding EU country. The focus was not on protein and GI.

*The glycaemic index is a measure of the increase in blood sugar triggered by carbohydrate-containing foods. The higher it is, the greater the insulin release and the more fat burning is slowed down.

Study results

  • Participants in group 1 (low GI + high protein) gained the least weight. Even at the end of the study after six months, no yo-yo effect was observed. In addition, fewer participants from this group dropped out of the study.
  • In group 4 (high GI + low protein), body weight increased most significantly with an average of 1.67 kilograms.


In contrast to carbohydrates and fats, foods containing protein have a favourable effect on long-term weight loss success, e.g.:

  • Lean meat
  • Poultry
  • Fish
  • Eggs
  • Low-fat dairy products
  • Pulses
  • Nuts and almonds. Proteins are more filling than carbohydrates and fat.

Foods with a low GI cause blood sugar to rise more slowly and to a lower level than carbohydrate-containing foods with a high GI. If blood glucose rises too quickly, undesirable effects are the result, affecting both metabolism and mental performance.

Whole grain products have a lower GI than white flour products, for example. Therefore, wholemeal bread, wholemeal pasta, wholemeal oatmeal and wholemeal cereals should be preferred whenever possible.

The authors of the Diogenes study2 cite protein-rich meals with a low GI as an example:

Time of day Meals
Breakfast Muesli with low-fat yoghurt, crispbread with low-fat cheese and 1 orange
Snack (morning) Vegetable sticks and lean cheese sticks
Lunch wholemeal rye bread with lean meat or poultry cuts; mackerel in tomato sauce and mixed vegetables
Snack (afternoon) Wholemeal rye bread with reduced-fat liver pate and cucumber
Dinner Pan-fried turkey with vegetables and wholemeal pasta; avocado salad with feta cheese and sugar snap peas
Drinks with meals Water; Low-fat milk

"The Diogenes study shows that the current dietary recommendations are not ideal for preventing overweight individuals from gaining weight again," informs Andreas Pfeiffer, Head of the Department of Clinical Nutrition, German Institute of Human Nutrition (DIfE).

"A diet with a slightly higher protein content than that currently recommended and a low GI makes it easier for overweight people to maintain their reduced body weight in the longer term after a reduction diet. In addition, the study participants seem to find it easier to permanently change their diet to such a form of nutrition," Pfeiffer sums up.

Study #2: The gut as a key factor?

A 2016 study by the Weizmann Institute of Science, Rehovot, found that obesity leads to a lasting change in the gut flora, which largely persists even after dieting and promotes renewed weight gain3.

Study details

For the analysis, mice were subjected to the yo-yo effect. The normal-weight animals first gained weight and then lost it again after a calorie-reduced diet. After several cycles, the yo-yo effect set in and the mice gained weight significantly faster.

The research group's assumption: The excess weight had left traces in the animals' bodies that permanently changed their reaction to energy-rich food - but where? The comparison with the normal-weight control group showed no differences in energy burning, insulin production, cholesterol levels, oxygen consumption or exercise behaviour.

Study Results

The research group found what they were looking for in the intestinal flora. "The microbiome in the digestive tract had not returned to its original state after the diet," reports Christoph Thaiss and his colleagues from the Weizman Institute of Science in Rehovot. It is known that obesity leads to a shift in the composition of bacteria. Dysbiosis, i.e. the imbalance of the intestinal flora, is a co-trigger for concomitant diseases of obesity.

The study showed that the intestinal flora balance was not restored after the end of a diet. It took 21 weeks for the intestinal flora to return to normal after being overweight for four weeks.

To find out whether the bacteria in the intestine are causally involved in the yo-yo effect, the scientists conducted further experiments. The intestinal flora of formerly overweight mice was transplanted into the digestive tract of slim control mice. The result: if these mice were now given a somewhat higher-fat diet, they also suffered from the typical yo-yo effect - even though they were neither overweight nor had been on a diet.


A targeted focus on balancing the gut flora and metabolism could help sufferers lose weight in the long term.

Do you have a genetic tendency to the yo-yo effect?

Individual genetic conditions can also play a role in the yo-yo effect. Among other things, so-called single nucleotide polymorphism (SNP), i.e. variations in our gene interaction that influence our health, are responsible for this. That is why there is no "one" diet that leads to the desired goal for everyone in the same way. Losing weight without the yo-yo effect can be more successful with a metabolism-appropriate diet.

The igevia metabolic test is based precisely on this and analyses 23 SNPs in 19 genes. The genes ACVR1B, ADRB2, ADRB3, FTO, LEPR and MLXIPL can, for example, provide information about whether you are prone to the yo-yo effect. According to the results, you will receive individually tailored diet and exercise recommendations, including food recommendations and a 14-day diet plan with recipes.

Find out if you are genetically prone to the Yo-Yo effect


This article has been reviewed by unserem Medical-Team for accuracy of content.


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