Researchers have identified the potential for lifestyle changes to prevent and treat obesity without surgery.
Weight loss surgery can reduce the levels of bile acid associated with higher appetite, as can taking fibre supplements but to a lesser degree.
The study suggests that if this effect can be mimicked through lifestyle changes, there could be potential to treat and prevent obesity, eliminating the risk posed by surgery.
The research by King’s College London, the University of Nottingham and Amsterdam University Medical Centre, sheds light on the molecules underlying the benefits of weight loss surgery ( also known as bariatric surgery) on appetite and metabolism.
There are several different types including reducing the size of the stomach or rerouting the top part of the stomach to the small intestine.
The surgery is an invasive procedure but can lead to significant improvements in weight loss, metabolic health and a reduction in appetite, but the reasons are unknown.
Joint lead author Dr Cristina Menni, of King’s College London, said: “The study’s results have important implications for the development of targeted interventions for metabolic disorders focused on the gut microbiome.
“By better understanding the complex interplay between genetics, the gut microbiome, and diet in regulating bile acid levels and their impact on appetite and metabolic health, we may be able to develop new strategies for preventing and treating obesity and metabolic syndrome.”
Bile acids – acids found predominantly in fluid (bile) that is made and released by the liver and stored in the gallbladder – are a marker of poor heart and metabolic health and can affect liver function and inflammation.
Researchers studied a group of patients in Amsterdam who had undergone bariatric surgery, and measured levels of bile acids before surgery and a year later.
They also studied bile acids from two population studies: TwinsUK, run by King’s College London; and Predict, run by King’s and personalised nutrition company, Zoe.
According to the findings, levels of a specific bile acid called isoursodeoxycholate (isoUDCA), which is associated with higher appetite and worse metabolic levels, fell after bariatric surgery and after taking fibre supplements.
However, levels of the acid did not decrease after consuming omega-3 supplements.
Scientists say that understanding these mechanisms may enable the development of new interventions that mimic the effects of bariatric surgery without putting patients through an invasive procedure.
Bariatric surgery is also only suitable for those severely obese, and understanding whether isoUDCA can be modified by lifestyle interventions could lead to targeted treatments for obesity.
The research also suggests that gut bacteria is key to determining the outcomes of bariatric surgery and sheds light on the ways in which gut microbes modify a person’s metabolism.
Joint lead author Professor Ana Valdes, of the University of Nottingham, said: “What our study shows is that specific microbial metabolite is involved in some of these benefits and that, although to a more modest extent, dietary fibre might mimic some of these effects.
“This could help design dietary supplementation studies aimed at increasing satiety and improving liver parameters.”
Co-author Professor Tim Spector, professor of genetic epidemiology at King’s College London and co-founder of Zoe, said: “This study highlights the key role that fibre plays in appetite regulation and metabolism, harnessed by specific gut microbes.
“Advanced gut microbiome testing (as used by Zoe) provide personalised insights that can support metabolic health.
“The gut microbiome and its chemical products such as these bile acids hold huge promise for reducing obesity without the need for invasive surgery.”
The findings are published in the journal Cell Reports Medicine.