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How Do Genetic Factors Affect Body Composition and the Response to Exercise?
Bouchard C. Evidence for gene-nutrition and gene-physical activity interactions. Master Lecture, Society for Behavioral Medicine conference. San Francisco, March 24, 2006. Dr. Bouchard is a world-renowned geneticist and exercise physiologist. In this lecture, he presented an overview of his decades of research. In a series of studies with identical twins, Dr. Bouchard assessed the effects of excess calorie consumption or a deficit in calorie consumption. Studies with identical twins are an exquisite way to study the role of genetic factors. The study participants were isolated in a lab for 12 weeks with all food consumption and physical activity monitored and controlled. Participants could not leave the lab during the 12-week studies. In the over-eating study with lean, young, male identical twins, Dr. Bouchard found that there was a wide variation of weight gain from the excess of 85,000 calories over the 12 weeks of the study. If the standard applies that an excess of 3,500 calories equates to a pound of weight gain, then the expectation is that the participants would gain about 24 pounds.
The results showed that some twin pairs gained a great deal of weight, some a modest amount of weight, and some only a small amount of weight. Variation of weight gain was primarily based on genetic factors. This means that the weight gain of each twin in a pair was very similar while the weight gain between twin pairs was dissimilar. Different people adapt differently to excess calories In another twin pair study with overweight, young male twin pairs using the same isolated lab, men participated in two 55-minute exercise sessions per day on 10 of 11 days over a 12-week test period. Exercising created a 55,000 calorie deficit that on average would equate to about a 16 pound weight loss. Weight loss was, however, highly variable and primarily related to genetic factors. Twins in a pair lost about the same amount of weight while different pairs lost different amounts of weight. The study shows that people will respond differently to a calorie reduced diet. The studies showed that genetic factors largely determine the bodyweight and body composition response to over-eating or under-eating. Interestingly, in both studies, after an extended follow-up when men were no longer in the restricted lab and back in their regular life, their bodyweight returned to within about two pounds of their original weight before the start of the study. These data provide some support for the ‘set-point’ theory of bodyweight. In one study from the Heritage Family Study, a large number of people from the study’s families were trained with a standard, supervised aerobic training program in a 20-week study. Using standard measures for aerobic capacity, the results of the study showed there was a very wide range of responsiveness to aerobic training. Some people showed great responsiveness and some showed virtually none. Many people showed a modest level of responsiveness. Family members were very similar in their response to training. These data showed that genetic factors played a large role in how different people respond to aerobic training. Bottom-line: Genetic factors beyond your control have a good deal to do with how you respond to food consumption and exercise. This does not mean efforts to improve your nutrition and training are futile because ‘everything is genetics’. It does mean that because genetic factors are so influential, we need to study and understand how we as individuals best respond to changes in nutrition, types of exercise, and time for recovery. Unless you have an identical twin, you are not a ‘carbon copy’ of someone else. Through planning, tracking, and monitoring your eating, training, and recovery time, you can readily see what works best for you. It also is likely that how we like to do things has some basis in genetics. We all have characteristic behaviors that mark how we perform tasks in different situations. If we’re fortunate, we find tasks that best fit our characteristic behaviors. We then tend to perform well in those situations and are readily rewarded. In that sense, because of our genetic characteristics and behavior patterns, we are ‘naturally selected’ and repeated rewarded for performing certain tasks in certain ways. We learn to play to our strengths. It’s a matter of capitalizing on what works best for each of us. This conclusion is very similar to the ideas that in training and other areas of our life, we do best and typically most enjoy behaviors and situations that best use our talents and skills.
Bouchard C. Evidence for gene-nutrition and gene-physical activity interactions. Master Lecture, Society for Behavioral Medicine conference. San Francisco, March 24, 2006. Dr. Bouchard is a world-renowned geneticist and exercise physiologist. In this lecture, he presented an overview of his decades of research. In a series of studies with identical twins, Dr. Bouchard assessed the effects of excess calorie consumption or a deficit in calorie consumption. Studies with identical twins are an exquisite way to study the role of genetic factors. The study participants were isolated in a lab for 12 weeks with all food consumption and physical activity monitored and controlled. Participants could not leave the lab during the 12-week studies. In the over-eating study with lean, young, male identical twins, Dr. Bouchard found that there was a wide variation of weight gain from the excess of 85,000 calories over the 12 weeks of the study. If the standard applies that an excess of 3,500 calories equates to a pound of weight gain, then the expectation is that the participants would gain about 24 pounds.
The results showed that some twin pairs gained a great deal of weight, some a modest amount of weight, and some only a small amount of weight. Variation of weight gain was primarily based on genetic factors. This means that the weight gain of each twin in a pair was very similar while the weight gain between twin pairs was dissimilar. Different people adapt differently to excess calories In another twin pair study with overweight, young male twin pairs using the same isolated lab, men participated in two 55-minute exercise sessions per day on 10 of 11 days over a 12-week test period. Exercising created a 55,000 calorie deficit that on average would equate to about a 16 pound weight loss. Weight loss was, however, highly variable and primarily related to genetic factors. Twins in a pair lost about the same amount of weight while different pairs lost different amounts of weight. The study shows that people will respond differently to a calorie reduced diet. The studies showed that genetic factors largely determine the bodyweight and body composition response to over-eating or under-eating. Interestingly, in both studies, after an extended follow-up when men were no longer in the restricted lab and back in their regular life, their bodyweight returned to within about two pounds of their original weight before the start of the study. These data provide some support for the ‘set-point’ theory of bodyweight. In one study from the Heritage Family Study, a large number of people from the study’s families were trained with a standard, supervised aerobic training program in a 20-week study. Using standard measures for aerobic capacity, the results of the study showed there was a very wide range of responsiveness to aerobic training. Some people showed great responsiveness and some showed virtually none. Many people showed a modest level of responsiveness. Family members were very similar in their response to training. These data showed that genetic factors played a large role in how different people respond to aerobic training. Bottom-line: Genetic factors beyond your control have a good deal to do with how you respond to food consumption and exercise. This does not mean efforts to improve your nutrition and training are futile because ‘everything is genetics’. It does mean that because genetic factors are so influential, we need to study and understand how we as individuals best respond to changes in nutrition, types of exercise, and time for recovery. Unless you have an identical twin, you are not a ‘carbon copy’ of someone else. Through planning, tracking, and monitoring your eating, training, and recovery time, you can readily see what works best for you. It also is likely that how we like to do things has some basis in genetics. We all have characteristic behaviors that mark how we perform tasks in different situations. If we’re fortunate, we find tasks that best fit our characteristic behaviors. We then tend to perform well in those situations and are readily rewarded. In that sense, because of our genetic characteristics and behavior patterns, we are ‘naturally selected’ and repeated rewarded for performing certain tasks in certain ways. We learn to play to our strengths. It’s a matter of capitalizing on what works best for each of us. This conclusion is very similar to the ideas that in training and other areas of our life, we do best and typically most enjoy behaviors and situations that best use our talents and skills.
