People come in all shapes and sizes ““ tall, short, heavy, thin, wider hips, rounder stomach, tiny butt, you name it. Much of how we look, including how easy it is for us to gain weight or where we store it, is genetic. Whether you store extra fat on your hips, butt or gut is passed down the family tree. But does nature dictate whether some of us are “designed” to store fat easier than others? The answer is yes to some degree, but how much is stored has a lot to do with lifestyle.
What makes obesity and heredity particularly hard to study is that it can be tough to tease out whether someone inherited a gene for obesity, or diet and lifestyle habits that are likely to make you gain weight. For most of us it’s a bit of both. Besides sharing genes, families tend to develop a lot of the same habits ““ like a tendency to be sedentary, skip meals, eat a lot of junk food, or participate in a lot of “screen time” ““ all of which can lead to weight gain over time.
What Does the Science Say?
Several genes have been tied to weight but the relationship is extremely complex and not well understood. One hypothesis is that humans evolved to have a “thrifty gene” that was designed to help us avoid starvation throughout most of history when our environment was different (food was scarcer and daily life was very physical). In other words, genes that used to help us avoid starving to death are now backfiring and causing us to gain too much weight! Genes take thousands of years to evolve, so our genes have not changed over the last few decades when obesity rates have really taken off. This suggests that factors outside of genetics are largely driving this epidemic. Genes may also influence how naturally active or sedentary a person may be, likely explaining why some of us love to be active and others hate it!
One study of over 2700 children found that those who had a gene tied to obesity called the FTO gene were more likely to be overweight. On further study of the FTO gene positive kids, researchers found that they didn’t seem to have a slower metabolism, but were prone to eating more food, particularly food that was high in calories.
Another study of over 700 Amish people found that those who had the FTO gene were only likely to be overweight if their physical activity was low, suggesting a genetic predisposition to being overweight could be mediated by exercise.
Clearly genes can make some of us more likely to gain weight in this environment where food is, if anything, too available, and daily life requires very little physical exertion. Whether you have “the gene” or not, the strongest influence on weight is lifestyle ““ how and what you eat and how much you exercise. To control your weight the goal is the same: eat less, exercise more, try to work fruits and vegetables into your diet and watch those liquid calories from soda and other drinks.
After 12 years as a nutrition-based educator for Harvard Vanguard Medical Associates (HVMA), the Domar Center for Mind/Body Health’s Director of Nutrition Hillary Wright transitioned to a part-time position at Dana Farber Cancer Institute in Boston. She is also the founder of New Vision Nutrition in Arlington, Massachusetts — a private nutrition consulting practice that includes nutrition counseling, public speaking, and teaching nutrition to colleges and institutions. She is a contributing editor and regular writer for the newsletter “Environmental Nutrition” and is currently working with the Arlington Public Schools on grant-funded programs designed to increase nutrition, education and physical activity in the community. Hillary’s clinical interests include women’s health and nutritional management of polycycstic overy syndrome (PCOS).