Are You an Apple or a Pear?

Study looks at genetic obesity causes, fat distribution

/ Author:  / Reviewed by: Joseph V. Madia, MD

The results are in from the largest genetic investigation of human traits to date, and they aren’t pretty.

An international consortium has identified 18 new gene sites associated with overall obesity and 13 that affect fat distribution after assessing data from nearly a quarter-million patients. The studies combine the talents of more than 400 scientists at 280 institutions across the globe and appear in the journal, Nature Genetics.

That means scientists are closer to being able to tell you why that cheesecake goes straight to your thighs or your belly – why you’re pear-shaped or apple-shaped, that is.

“Different people have different susceptibilities to obesity,” said Joel Hirschhorn, MD, PhD of Children's Hospital Boston and the Broad Institute, a senior author involved with the two studies. “Some don't rigorously watch what they eat or how much they exercise and still resist gaining weight, while others constantly struggle to keep their weight from skyrocketing.”

Ever wondered why your friend can eat as much as you do and not gain an ounce while just looking at that extra slice of pizza seems to make you pack on the pounds? Hirschorn said the studies’ main goal was to determine why different people have different inherited susceptibility to obesity.

“One of the most exciting parts of this work is that most of the (Body Mass Index) BMI-associated variants identified are in or near genes that have never before been connected to obesity,” said Elizabeth K. Speliotes, MD, PhD, MPH, of Massachusetts General Hospital and the Broad Institute, who took part in the studies. Overall researchers found 18 genetic sites that weren’t previously associated with obesity.

Researchers also discovered that individuals who carried more than 38 BMI-increasing genetic variants were on average 15 pounds to 20 pounds heavier than those who carried fewer than 22 such variants. Theoretically people could have up to 64 genetic variants affecting their risk, Dr. Speliotes said. 

Now as far as where the calories from that cheesecake travel to, it’s best to have some extra padding on the hips and thighs (pear-shape) rather than have the fat accumulate on the abdomen or mid-section (apple-shape). Abdominal fat is associated with a higher risk of diabetes and heart disease, whereas fat around the hips and thighs may provide protection against such diseases, according to studies. 

So, now that you know the role your genes play in gaining weight, what can you do to take control of your weight?

One study suggests drinking milk, of all things. Research from the Ben-Gurion University of the Negev (BGU) reveals that dieters who consumed milk or milk products lost more weight than those who consumed little to no milk products. Furthermore participants with the highest dairy calcium intake lost about 12 pounds on average by the end of the two-year study.

Another recent study observing 442 overweight or obese women, ages 18 to 69, over a two year period found that women who engaged in a one-to-one weight-loss counseling program (that included prepackaged prepared meals and increased physical activity for 30 minutes a day) lost an average of 16 pounds.

Reviewed by: 
Review Date: 
October 11, 2010