The reason behind why some people gain weight easily, while others can eat to their heart’s content without any change in their weight may be explained by the latest research in the International Journal of Obesity, the first of its kind to link changes in weight over several years to gut bacteria.
This research goes hand in hand, with the study in Israel that explained why people often regain the weight they lose after dieting. This study found that mice who were put on a yo-yo diet were more likely to gain weight compared to mice on a longer-term, steady diet. The theory behind this was that the yo-yo dieting reduced microbial diversity and volume. Furthermore, when the microbes were transplanted from the yo-yo dieters to the non-yo-yo dieters, those mice also gained weight.
Can we apply the same theory to humans?
In this recent study performed in the UK, 1632 women, all twins, were tracked over 9 years. It was found that those who were weight-stable for the 9 years, or lost weight steadily, had a large variety of microbes, ate more fiber, and had more abundance of certain types of gut microbes.
At DayTwo, we know that gut bacteria will influence how a body converts food into energy, and this depends on both the type and amount of microbes.
In the twins UK study, body weight was measured at the start and then 9 years later. The participants were asked questions about food and amounts they ate and their weights. At the completion of the study, they provided a fecal sample, measured their weight again and had their gut bacteria analyzed.
Most of the women gained weight over the 9 years. However, this was not fully explained by how many calories they consumed in their diet. Being that the participants were twins, they were able to calculate how much of the weight gain can be explained by genes. The study showed that only 41% of the weight gain was explained by genes, meaning there were other factors that influenced these changes.
Women who ate more dietary fiber (found in vegetables, fruit, whole grains, legumes) were less likely to gain weight compared to those who ate little fiber, even if they consumed the same amount of calories. Furthermore, participants that lost weight or maintained their weight had a more diverse microbiome. They were also able to pinpoint certain bacteria that were different between women who gained or lost weight. A lot of these bacteria had been previously discovered in mice to be involved in better energy metabolism.
This study shows that dietary interventions can influence microbiome diversity which can therefore affect weight gain or weight loss.