Researchers at Tulane University and Harvard University, led by Lu Qi, a professor of epidemiology, acknowledge in a study published today that obesity is a “multifactorial disorder that has a genetic predisposition” that can be triggered by environmental influences such as the shift in the US diet from one high in fiber and carbohydrates to one high in sugar, fat and animal products.
But, their research shows that people at high genetic risk for obesity are not condemned to an unhealthy weight or having to work harder to lose weight than those without their genetic make up.
Rather, they say, people at high genetic risk for obesity actually are “more susceptible to the beneficial effect of improving diet quality on weight loss.”
Their observation is based on a 20-year follow-up study that examined women from the Nurses’ Health Study and men from the Health Professionals Follow-up Study who followed either the Alternate Healthy Eating Index 2010 (AHEI-2010), the Dietary Approach to Stop Hypertension (DASH diet) or the Alternate Mediterranean Diet (AMED).
After reviewing data from every four years, the researchers found that in general for each additional 10 risk alleles in participants’ genetic makeup, there was an associated increase of 0.02 kg of body mass index and 0.05 kg increase in body weight.
They also found that participants with a higher risk factor who followed the AHEI-2010 and DASH diets saw greater weight loss than those with a lower genetic risk. Specifically, they found changes in body mass index per 10 risk allele increments were 0.07 kg among those in the lowest third AHEI-2010 score and 0.01 kg among those in the highest third with increased AHEI-2010 scores, which corresponds to a weigh change of 0.16 kg versus -0.02 kg.
A similar change was seen in those who followed the DASH diet, but not the AMED diet.
What this means is “people with a greater genetic predisposition seem to be more susceptible to the favorable effect of improving diet quality on weight management,” according to the study.
The authors did not know the precise mechanisms for the change, but hypothesize that genes associated with body mass index that have been shown to influence appetite regulation and energy homeostatis, may also be responsible for the weight loss.
“Our results suggest that weight gain associated with genetic predisposition can be at least partly counteracted by improving adherence to health y dietary patterns,” the researchers conclude, emphasizing that “our findings support recommendation on adherence to healthy dietary patterns, particularly for people at high genetic risk of obesity.”