Fighting Genetic Predisposition to Obesity

Obesity tends to run in families, suggesting that it may have a genetic cause. However, family members share not only genes but also diet and lifestyle habits that may contribute to obesity. Separating these lifestyle factors from genetic ones is often difficult. Still, growing evidence points to heredity as a strong determining factor of obesity.

It is,  not known whether and to what extent this genetic susceptibility may be attenuated by a physically active lifestyle. We aimed to assess the influence of a physically active lifestyle on the genetic predisposition to obesity in a large population-based study. In the study of 20,430 individuals (aged 39-79 y) from the European Prospective Investigation of Cancer (EPIC)-Norfolk cohort with an average follow-up period of 3.6 y were studied. A genetic predisposition score was calculated for each individual by adding the body mass index (BMI)-increasing alleles across the 12 SNPs. Physical activity was assessed using a self-administered questionnaire. Linear and logistic regression models were used to examine main effects of the genetic predisposition score and its interaction with physical activity on BMI/obesity risk and BMI change over time, assuming an additive effect for each additional BMI-increasing allele carried. It was concluded that living a physically active lifestyle is associated with a 40% reduction in the genetic predisposition to common obesity, as estimated by the number of risk alleles carried for any of the 12 recently GWAS-identified loci.

Although genes are an important factor in many cases of obesity, a person's environment also plays a significant part. Environment includes lifestyle behaviors such as what a person eats and how active he or she is. Women tend to have high-fat diets, often putting taste and convenience ahead of nutritional content when choosing meals. Most don't get enough exercise.

People can't change their genetic makeup, of course, but they can change what they eat and how active they are. Some people have been able to lose weight and keep it off by:  

• Learning how to choose more nutritious meals that are lower in fat - A poor diet  to high-calorie foods that are widely available, low in cost, heavily promoted, and good tasting. These ingredients produce a predictable, understandable, and inevitable consequence-an epidemic of diet-related diseases. While such foods are fast and convenient they also tend to be high in fat, sugar, and calories. Choosing many foods from these areas may contribute to an excessive calorie intake. Some foods are marketed as healthy, low fat, or fat-free, but may contain more calories than the fat containing food they are designed to replace. It is important to read food labels for nutritional information and to eat in moderation. Also, people may be eating more during a meal or snack because of larger portion sizes. This results in increased calorie consumption. If the body does not burn off the extra calories consumed from larger portions, fast food, or soft drinks, weight gain can occur.

For more information on healthy eating, visit our handout for adults on making healthier choices.

• Learning to recognize environmental cues (such as enticing smells) that may make them want to eat when they are not hungry- To regain the ability to eat only when you are hungry, you must understand that not all hunger is physical. Today, while almost no one eats only when they are physically hungry, many people eat when they are psychologically hungry. You may be enticed by a succulent hamburger in an advertisement on television and start to think you're hungry. You may eat on schedule whether you feel hungry or not. You may be bored, tired, sad, happy or nervous. These are all types of psychological hunger. Listening to and heeding your body's signals of hunger and fullness can help you to achieve or maintain a healthy weight, which lowers the risk of many chronic diseases. In addition, eating is more pleasurable when you are truly hungry. Therefore, when your body indicates it is time to eat, choose foods you love and take the time to enjoy them.

• Becoming more physically active-  The U.S. Department of Health and Human Services recently released updated guidelines recommending that children and adolescents participate in physical activity for 60 minutes per day or longer, with most exercise being of moderate to vigorous intensity. Physical activity contributes to the prevention and treatment of obesity, not only by increasing energy expenditure but also by modulating the signals of satiety and reducing food intake.

Thus we can conclude that even those who have the highest risk of obesity from their genes can improve their health by taking action.