Moving beyond BMI
Interestingly, the researchers controlled for baseline body mass index (BMI) and other factors that could affect weight loss. People who start off with a higher BMI tend to lose more weight than others, a phenomenon known as ‘regression to the mean.” This factor confounded some earlier research, they noted.
“The vast majority of features associated with weight loss, independent of BMI, were functional genes within the gut metagenome,” Dr. Gibbons said.
“This tells us that the gut microbiome is an important modulator of weight loss, independent of your underlying metabolic health state, baseline diet, or BMI status.”
“This study described several metagenomic functional features that were associated with weight loss after controlling for potential confounders, such as age, sex, and baseline BMI,” Dr. Kahleova said. “These findings ... may help optimize the weight-loss protocols in future studies.”
Fecal microbiota transplants?
What do the findings mean for people willing to adjust their diet – or undergo a fecal transplant – to include more of the gut bacteria that facilitate weight loss?
It could be too soon for such interventions, Dr. Gibbons said. “It is still very difficult to rationally engineer your gut microbiome.”
“Interestingly, a recent study suggests that fecal transplants from a high-Prevotella donor may be able to flip low-Prevotella recipients to high-Prevotella,” Dr. Gibbons said.
More research is required, however, to understand whether or not these fecal microbial transplant-flipped individuals are also more capable of weight loss, he added.
Beyond that, “I can’t give any specific recommendations, other than that [people] should eat more fiber-rich, plant-based, whole foods and reduce their consumption of red meat. That’s well-supported.”
“Also, prepare your own meals, rather than relying on sugar and sodium-rich processed foods,” Dr. Gibbons said.
Dr. Gibbons and his team hope to validate their work in larger human studies “and perhaps develop clinical diagnostics or interventions for people trying to lose weight.”
A version of this article first appeared on Medscape.com.