London - Yo-yo dieters may struggle to stay slim because of a lack of diversity in their gut bacteria, according to a new study.
The findings may also explain why obese people struggle to keep weight off after a successful diet.
A balanced “community” of beneficial bacteria in the gut has been found to keep weight off.
Certain gut bacteria in obese individuals have been found to be better at helping the body extract energy from food. Surplus energy – which the bacteria is helping us to collect – is converted in the body to fat. It is thought that reducing levels of this type of bacteria and increasing levels of other bacteria that do not have this property could help stave off obesity and diabetes.
German researchers from University Hospital Schleswig Holstein in Kiel put eighteen obese adults on a diet of just 800 calories per day for a three-month period and tracked how much weight they lost.
They also measured their sensitivity to insulin, as well as both the activity and diversity of their gut bacteria using stool samples.
They then tracked the same factors after putting the dieters on a weight maintenance diet for a further three months.
The researchers then compared the results to thirteen obese (control group) and thirteen lean adults who followed their regular diets throughout.
Compared to the control group, they found that the bacteria in the guts of the obese dieters had become more diverse at the end of their three months of dieting. But the diversity of bacteria in the gut – known as the gut microbiome - was not sustained during the three-month weight maintenance phase, and reverted back to a similar state as before.
This was despite the dieters losing an average of just over 3 stone (20kg) overall and having improved insulin sensitivity at the end of the six month period.
One of the limitations of the study is that the medications patients may have been taking was not accounted for, which could have an impact on gut bacteria diversity and metabolism.
Dr Matthias Laudes, the lead author of the study said: “Anti-obesity campaigns often recommend low calorie diet programmes such as the one we offered here. However, our work shows that this is not making enough of a long-term change in obese people’s gut bacteria, which may explain why so many of them put weight back on”.
“We want to know why the gut microbiome is resistant to maintaining change after dieting,” he continued.
“In the future we will look at the potential of using prebiotics during weight maintenance, or even the potential of faecal transplantation from a healthy gut to that of an obese patient”.
The research was presented at a meeting of the European Society of Endocrinology.
Daily Mail