People come in all shapes and sizes – tall, short, heavy, thin, wider hips, rounder stomach, 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 more easily than others? The answer is yes to some degree, but how much is stored has a lot to do with lifestyle.  

Heredity or Habits?

What makes obesity and heredity particularly hard to study is that it can be tough to tease out whether someone inherited a tendency to be overweight (there is no gene for obesity), or if it is diet and lifestyle habits that are likely to make that person gain weight. For most of us it’s undoubtedly 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. Let’s look at a few basic facts about what influences weight:

• Overweight and obesity results from eating too many calories and not getting enough activity. 

• Body weight is influenced by many factors: genes, metabolism, behavior, environment, culture, and socioeconomic status. 

• Behavior and environment play a big role in causing people to be overweight and obese.

The Genetic Piece

• Several genes have been tied to body mass index/weight but the relationship is extremely complex and not well understood. With the exception of a few genetic diseases where people tend to become really overweight, it’s a combination of genes and behaviors together that cause obesity. 
• 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. In those days 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 driving this epidemic. 
• Genes may 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 2,700 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 kids with the FTO gene, 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 reduced by exercise.

On The Move:

Make physical activity part of your daily routine with simple steps, such as walking the dog or riding your bike to school.

The Bottom Line

Clearly genes can make some of us more likely to gain weight in this society where food is, if anything, too available, and daily life requires very little physical exertion. Our “primitive genes” probably made for a hearty caveman, but under modern conditions can make it aggravatingly easy to gain weight. 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 for everyone: eat less, exercise more, try to work fruits and vegetables into your diet as much as possible and watch those liquid calories from soda and other drinks with a lot of sugar.

This article was reviewed by BodiMojo expert Dr. Jessica A. Hoffman.