Roux-en-Y gastric bypass surgery does not only shrink waists, but also results in gene-expression alterations, researchers from the Karolinska Institute, Stockholm, Sweden, and the University of Copenhagen, Denmark, reported in the journal Cell Reports.

Professor Juleen Zierath and team explained that gastric bypass surgery, which is often performed on obese patients, can significantly reduce their body weight in a short time. They add, that for reasons that are not entirely clear, the surgical procedure can also bring patients with type 2 diabetes into remission. However, bypass surgery can only help diabetes, it is not a cure.

The team also found that in extremely obese patients, the levels of genes that control fat burning and storage are altered, leading to poor metabolic health. Gastric bypass surgery seems to help bring these genes back to a healthy state.

Zierath and team believe this gene-expression correction that occurs after surgery contributes significantly to their weight loss and improved metabolism.

Professor Juleen Zierath said:

“We provide evidence that in severely obese people, the levels of specific genes that control how fat is burned and stored in the body are changed to reflect poor metabolic health. After surgery, the levels of these genes are restored to a healthy state, which mirrors weight loss and coincides with overall improvement in metabolism.”

Specifically, DNA modifications that control gene expression in response to the environment occurred after the post-surgery weight loss, the researchers found after probing deeper.

Changes in methylation (chemical markings) on PGC-1alpha and PDK4, two genes that control glucose and fat metabolism, occur when people become very obese. When the patient loses weight after gastric bypass surgery, the changes in methylation are reversed. This finding suggests that food intake or weight loss (i.e. the environment) can affect gene expression through this mechanism.

Lead author, Romain Barrès, said:

“The novelty of our work originates with the finding that DNA methylation is altered by weight loss.”

The authors believe their findings may be useful when trying to design new medications that mimic this weigh-loss-linked control of gene regulation.

Changes in the mix of microbes in the gut – in a previous study, scientists from the Obesity, Metabolism and Nutrition Institute at Massachusetts General Hospital reported in the journal Science Translational Medicine (March 2013 issue) that the weight loss patients experience after gastric bypass surgery might be because of the changes in the mix of microbes in their gut.

Written by Christian Nordqvist