Holiday weight gain: is it genetically determined?

Many of us anticipate weight gain during the holidays because of the rich and varied foods associated with holiday celebrations. The American Council on Exercise (ACE) estimates that the average citizen consumes 4,500 calories and gains 3-7 pounds on Thanksgiving alone. Some of us will gain more than others, and some of us will struggle more to lose the added weight come January 1, 2011. Besides lamenting over this seemingly unfair fact, what can we learn about our genetic propensity for weight gain?

Healthy weight management is frequently a core goal amongst the patients I treat in my private practice in the Bay Area, CA. Most people aiming to improve their mental health recognize that a key component of emotional well-being is maintaining healthy diet and exercise habits. In my clinical experience, there is a good deal of variance in people’s willingness and ability to accomplish their healthy eating and exercise goals.

Family, twin, and adoption studies examining the genetic influence of weight gain suggest that at least 70% of our weight is genetically determined, and perhaps as heritable as our height. Some experts in the field believe weight is more heritable than other conditions, including heart disease, breast cancer, hypertension, or even mental illness. Claude Bouchard & colleagues conducted experiments on a metabolic unit in which different sets of identical twins were exposed to the same number of calories and same amount of exercise. The twin pairs each gained approximately the same amount of weight, however there were marked differences in weight gain amongst the different pairs of twins, despite exposure to the same amount of calories and exercise. Bouchard emphasizes that genetic variation “has much to do with the risk of becoming obese,” though clearly, there are environmental factors that play an important role in weight management.

It’s fairly common knowledge that our genes determine our body shape (take this quiz to determine if you are apple, pear, hourglass, petite or slim/athletic) and body type (take this quiz to determine if you are an endomorph, ectomorph or mesomorph), and our skill and motivation to exercise (it’s not uncommon for people to inherit their physical agility and coordination skills.) Researchers studying the Human Obesity Gene Map found that there are over 300 separate trait areas (loci) that may be involved in weight control.

So what does this mean for you this holiday season?

While our genes have an influence upon our weight and body type/shape, ultimately, our weight remains highly influenced by environmental factors, such as the diet and exercise regimen we choose. This holiday season, understand your genetic predisposition for weight gain, and make your choices accordingly.

Warden and Fisler suggest that the differences found in individual’s genetic profile could lead to greater flexibility in national recommendations such as the food pyramid for changes in lifestyle involving diet and exercise created to prevent obesity.

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2 thoughts on “Holiday weight gain: is it genetically determined?

  1. They Call Me Mr. Pibbs

    I think further distinction can be made within the category of inherited physiological weight control mechanisms. Differences might be in either the regulation of basal metabolic rate (hypothalamic-thyroid axis), or in the regulation of appetite (insulin, glucagon, leptin, cck production, secretion and sensitivity). Knowing which one is affecting a particular individual may aid in the identification and application of an appropriate intervention.

    Also, while the human body is fundamentally homeostatic, it does display a pretty high degree of plasticity in being able to adapt and set new metabolic set points in the face of persistent/repetetive stresses.

    1. Dear Mr. Pibbs, thank you for your offering a more in-depth, scientific backdrop for understanding why there appears to be variation in one’s body type and weight gain propensity. Further, it’s encouraging for people to consider how they may influence their body type and metabolism through exercise (persistent/repetitive stress). Much appreciated!

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