Tufts University researchers have determined the complicated formula by which saturated fats contribute to obesity in individuals with a genetic predisposition to be overweight.
The findings, published online in the Journal of the Academy of Nutrition and Dietetics, point the way to helping nutritionists develop diet plans that limit saturated fat for people whose genetic makeup increases their odds of being obese.
The study identified 63 gene variants related to obesity and used them to calculate a genetic risk score for obesity for more than 2,800 white, American men and women enrolled in two large studies on heart disease prevention. People with a higher genetic risk score, who also consumed a lot of saturated fat, were more likely to have a higher Body Mass Index (BMI), the ratio of body weight to height.
"We already know there are certain genes that interact with dietary fat and affect BMI," said senior author José M. Ordovás, a nutrition and genetics specialist and professor at the Friedman School of Nutrition Science and Policy at Tufts University.
"In the current study, we analyzed dozens of variants of those genes and other genes frequently associated with obesity risk and saw that, while total fat intake was related to higher BMI, people who were genetically predisposed to obesity and ate the most saturated fat had the highest BMIs."
Ordovás and colleagues suggested genetics make some people more sensitive to saturated fat, which is found mostly in fatty cuts of meats, including beef and pork, as well as butter, cheese, and other high-fat dairy products.
"Little is known about the mechanisms that might explain the role of saturated fat intake in obesity," said Ordovás. "Some clinical models suggest that saturated fat might interfere with activity in the part of the brain that lets us know we're full, in addition to a few studies in people that suggest a diet high in saturated fat interferes with satiety. More research is needed to know whether those findings would also apply to gene function."
Genetic risk scores could be useful in identifying people who are predisposed to obesity and could ultimately lead to personalized dietary recommendations.
"If further research can clarify a relationship between obesity-related genes and saturated fat, people with higher scores would have even more incentive to follow advice to limit their saturated fat intake as part of an obesity prevention strategy," Ordovás said.
This research was funded, in part, by the National Institutes of Health.
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