When It Comes to Losing Weight, Genes Aren't the Whole Story

The worldwide obesity crisis begs the question: how much of weight gain is genetic, and how much should be blamed on environmental factors? A new study in BMJ finds that having 1 gene may make you more likely to gain weight, but it’s hardly a barrier to losing weight.¹

Researchers led by Katherine Livingstone, PhD, examined the FTO gene, the allele with the strongest associations in weight gain, apparently because it causes people to crave high-calorie foods and limits the feeling of fullness after a meal. The team analyzed data from nearly 10,000 participants who took part in randomized controlled trials to test the relationship between the FTO gene and various weight loss interventions, including diet, exercise, and therapy.

People who carry 2 copies of the FTO gene are more likely to be about 3 kg heavier than the rest of the population. But after checking for changes in body mass index, weight, and waist circumference from baseline to follow-up in the various trials, researchers found that people who carried the gene were not significantly less likely to lose weight during the various interventions—which means that while genes play a role in weight gain, by themselves, they are not the only culprit.

An editorial that appeared with the study said the results add to the evidence that environmental factors—especially bad food, and lots of it—have much more to do with worldwide weight gain than genetic factors.² The BMJ editorial noted that obesity in the United Kingdom now stands at 23% of all adults, and that country has just approved a tax on sugar-sweetened beverages. Obesity rates in the United States are much higher—the CDC recently reported a rate of 36.5%, and similar taxes are fought tooth-and-nail city by city. The American Beverage Association (ABA) last week sued Philadelphia over a tax it passed in June that is set to take effect January 1, 2017.

Data released today by the Center for Science in the Public Interest found that the ABA, Coca-Cola, and PepsiCo have spent $67 million since 2009 to fight local and state public health initiatives aimed at reducing soda consumption.

In January, the World Health Organization called for global efforts to pass soda taxes and marketing limits on sugary beverages to combat childhood obesity.

References

1. Livingstone KM, Celia-Morales C, Papandonatos GD, et al. FTO genotype and weight loss: systematic review and meta-analysis of 9563 individual participant data from eight randomised controlled trials [published online September 20, 2016]. BMJ 2016; 354:i4707. doi: http://dx.doi.org/10.1136/bmj.i4707.

2. Obesity treatment—are personalized approaches missing the point? [published online September 20, 2016]. BMJ 2016; 354 doi: http://dx.doi.org/10.1136/bmj.i4980.