Inherited genes that contribute to obesity can be somewhat mitigated by a physically active lifestyle, say researchers.
Obesity is a growing health concern globally; adverse health outcomes related to obesity include psychological disturbance, osteoarthritis, type 2 diabetes, hypertension, cardiovascular disease, cancer and up to 8-13 years shorter life expectancy.
Research has shown that obesity is more likely to occur in genetically predisposed individuals.
FTO is the human fat mass and obesity-associated gene that is strongly associated with obesity. Increased FTO expression has previously been shown to cause obesity in mice.
However, there is a growing consensus that excessive energy intake is a major contributor. As the epidemic coincides with an increasingly sedentary lifestyle, environmental factors would appear to play a role.
Could gene-environment interactions offer a way out?
Now, evidence is emerging of significant gene-environment interactions (GEI) in children and adult populations of European, East Asian and African ancestry, indicating that heritability estimates for obesity-related traits can be modulated by lifestyle factors such as physical activity.
David Meyre and colleagues from McMaster's Michael G. DeGroote School of Medicine, in Ontario, Canada, set out to investigate whether a physically active lifestyle could substantially decrease the genetic effect of the major obesity gene FTO on body weight in a multiethnic population.
The team looked at data from up to 17,400 people from six ethnic groups. The mean age of participants was 52.7 years, and the distribution of the cohort was 53.9% European, 18.9% Latino, 15.8% South Asian, 7.2% African, 2.9% Native American and 1.3% East Asian. Participants were from 17 countries, and they were followed for over 3 years.
The association between physical activity behavior and obesity was assessed by using both basic and precise (metabolic equivalent score) measures of physical activity, and traditional body mass index (BMI) was compared with the more recently developed body adiposity index.
Exercise reduces FTO effect by up to 75%
The researchers also analyzed the interaction between 14 obesity-related genetic traits and the effect of exercise.
Results suggest that physical activity can substantially reduce the influence of genetic factors on BMI in adults, blunting the genetic effect of FTO, the major contributor to common obesity, by up to 75%.
The scientists say that, in biological terms, the association is plausible: FTO is a nucleic acid demethylase, and FTO intron 1 variation is associated with different methylation profiles and BMI variance. Since methylation of DNA is sensitive to environmental changes such as physical activity and diet, they argue that there is a strong biological rationale for identifying GEI with FTO.
Studies have shown that PA can change the methylation and mRNA expression pattern of genes, including FTO, in both muscle and fatty tissue.
"This provides a message of hope for people with obesity predisposing genes that they can do something about it. Our body weight destiny is not only written in our genetic blueprint. These promising results encourage us to investigate how additional lifestyle factors, such as diet, stress and sleep patterns, may impact the genetic predisposition to obesity."
In light of the findings, the researchers conclude that "obesity prevention programs emphasizing vigorous PA for genetically at risk subgroups may be a valuable contribution to the global fight against obesity."
Medical News Today recently reported on a number of genetic and biological factors that can affect weight gain and loss.