Methane-producing bacteria. Mutating genes. Hunger-inducing hormones. Understanding the myriad microscopic factors inside our bodies that contribute to weight gain and obesity could help curb the epidemic—and tip the scale toward improved disease prevention.

In the clinic’s waiting room, Jenny M. is looking down, staring at her feet. She is fighting the urge to get up and walk out. The young woman has made appointments before, only to cancel them. But this time, she is determined. She is going to stop the disease that is ravaging her health—because this time she has a baby girl at home and wants to see her grow up. Adrienne Youdim, MD, has seen this many times. She offers assurances and puts her new patient at ease, inviting Jenny to open up about her feelings and fears.

Jenny does not have cancer or heart disease—though she is at risk for both. She has a condition shared by 68 percent of American adults: She is overweight.

We all know someone like Jenny. We also know that weight is a key risk factor in a number of serious health conditions besides heart disease and cancer, including stroke, diabetes, infertility, and Alzheimer’s disease. And we are very well aware that a healthy diet and regular exercise are paramount to good health. But what we did not know until very recently is that what is already inside us—genes, hormones, fat cells, and microbes—may be as important as the food we eat and, in some cases, more so.

Against the obesity epidemic, behavioral and lifestyle changes too often fail to produce any significant lasting changes. To find out why, scientists are taking a microscopic approach to the problem, with research into the molecular and cellular mechanisms that control appetite and weight gain—and their findings could have a sizeable and much-needed impact on disease prevention.

Tags: bacteria, BMI, Cancer, diabetes, genetics, genome, heart, Mark Goodarzi, microbiome, obesity, weight