Genes dictate effectiveness of diet, exercise in reducing body fat mass

Lifestyle modifications, such as diet and exercise, seem to be more effective at lowering body fat mass (BFM) in people who are more genetically predisposed to obesity, according to a recent Korea study.

“We investigated whether genetic factors, environmental factors, and the interaction of both play a role in determining the phenotypes, not only in obesity or BFM control but also in many other traits or diseases,” the researchers said. “Taken together, our findings clarify that genetic factors affect the efficiency of the lifestyle modification-induced BFM changes.”

The study included 259 adult volunteers (aged 23–67 years, 22.40 percent women) whose lifelog data were collected over 3 months using a wearable device. DNA was extracted from blood samples and subjected to genotyping in order to calculate the participants’ genetic risk score (GRS). Of particular interest was the susceptibility of BFM variations in response to carbohydrate intake (GRS-C), fat intake (GRS-F), and exercise (GRS-E).

Over the course of the study, participants were given four lifestyle modifications from which they could choose from: low-carbohydrate diet (n=35), low-fat diet (n=34), moderate-intensity exercise (n=99), and high-intensity exercise (n=83). Observational analysis showed that all four interventions led to notable anthropometric and blood chemistry improvements, with most participants demonstrating significant reductions in BFM, body mass index (BMI), and low-density lipoprotein cholesterol. [Sci Rep 2021;11:13180]

The researchers then divided participants into high- and low-genetic risk groups for each GRS, and then compared the magnitude of BFM change between subgroups.

Statistical analyses revealed stronger changes in BFM in participants with higher GRS. Likewise, the amount of GRS-matched lifestyle changes was directly proportional the change in BFM. That is, volunteers who were most active in their lifestyle modification and, at the same time, had high GRS, benefitted the most from their chosen interventions and saw greater changes in their BFM.

Notably, genetic predisposition seemed to be an influential factor in BFM control that it could even eclipse the effect of exercise. Participants who had high GRS but were inactive in their lifestyle modifications still recorded greater changes in BFM than comparators who were active in their chosen intervention but had low GRS.

“We demonstrated the potential smartphone- and wearable device-based body fat reduction programs in improving health status, as reflected in the improvements of anthropometric and blood chemistry indicators,” adding that “[b]y integrating lifelog and genomic data, we could construct … personal quantified health resources.”

Nevertheless, important limitations warrant consideration and point to the need for future studies. Among these are the study’s small sample size, missing values in lifelog data, using DNA microarray rather than whole genome sequencing, and uncaptured confounders.

“Ultimately this represents the need for designing the study with sufficient sample size and controls of selection and confounding bias to highlight the interaction between genetic variants and environmental factors affecting obesity,” the researchers said. “Future studies will seek to explore the application of wearable devices tracking the lifestyle and individual genome to healthcare and expand the studies in non-European populations.”