The combination of high-calorie diets and sedentary lifestyles has been considered the most significant environmental factor contributing to today’s obesity epidemic. However, new research from UCLA suggests that the ways our bodies respond to high-fat and high sugar foods are strongly inherited. The study found that there is a strong link between DNA and the amount of fat gained when a high-calorie, high-sugar diet– typical of a fast food meal–is consumed. The study in mice is the first of its kind to closely detail the metabolic responses to a high-sugar, high-fat diet.
During the 2 year experiment, the researchers studied fat tissue, obesity traits, global gene expression and intestinal bacteria in response to a high-fat, high-sugar diet in more than 100 strains of inbred mice. Through their study, 11 genome-wide “regions” linked with obesity and fat gains due to high-sugar, high-fat intake were identified. Many of these regions have also been connected with obesity in humans. Increases in body-fat percentage in response to the high-sugar and high-fat food varied widely among the mice strains, with increases ranging from 0 to 600 percent or more. Interestingly, most strains gained fat during the first four weeks of the diet and did not put on additional fat during the rest of the study. The study authors say this shows that there could be an upper body-fat set-point whereby genetic mechanisms restrict further accumulation in body fat. They also found that there is a high heritability of around 80 percent for body-fat percentage.
The results highlight the “importance of gene-by-environment interactions, with important implications for an understanding of the overall genetic architecture of obesity”, concluded the study authors. Future research will focus on the development of metabolic syndrome and diabetes as a result of a high-fat, high-sugar diet, as well as the role of specific, identified genetic factors in obesity.
“This study underscores the complexity of treating obesity”, said expert weight loss surgeon, Dr. Mona Misra of Los Angeles. “Everyone is clearly not on the same playing field. People eating the same types of foods will often respond in dramatically different ways, with some becoming morbidly obese much more easily than others. Diet and exercise alone may not be enough to prevent morbid obesity in the certain predisposed populations.”
Dr. Misra added that the study supports a genetic predisposition to morbid obesity and hopes that this research will help to increase awareness, compassion and understanding for those patients struggling against all odds to lose weight. “Most of these individuals will likely fail unless offered surgical intervention to successfully battle their weight problem and improve their health,” Misra concluded.
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