Genotype-Matched Diets Don’t Aid Weight Loss

As most people who have ever tried dieting know, there is no single diet strategy that is consistently superior to others for the general population. Some have suggested that genotype or insulin-glucose dynamics may affect diet outcomes.

Despite the hope that genotype-matched diets may make weight loss easier, a new study published Feb. 20 in the Journal of the American Medical Association shows that genotype-tailored diets don't impact weight loss.

In the Diet Intervention Examining The Factors Interacting with Treatment Success clinical trial, 609 adults aged 18 to 50 years without diabetes and with a body mass index between 28 and 40, were randomized to either a 12-month HLF (n=305) or HLC diet (n=304). The study also tested whether three single-nucleotide polymorphism multilocus genotype responsiveness patterns or insulin secretion (INS-30; blood concentration of insulin 30 minutes after a glucose challenge) were associated with weight loss.

The researchers found that 40 percent of participants had a low-fat genotype, while 30 percent had a low-carbohydrate genotype. However, weight change at 12 months was −5.3 kg for the HLF diet and −6.0 kg for the HLC diet. Over 12-months of weight loss there were no significant diet-genotype pattern interaction or diet-insulin secretion (INS-30) interaction with 12-month weight loss.

"There is considerable scientific interest in identifying genetic variants that help explain interindividual differences in weight loss success in response to diet interventions, particularly diets with varying macronutrient compositions," write the authors led by Christopher D. Gardner, Ph.D., from Stanford University in California. "In the context of these two common weight loss diet approaches, neither of the two hypothesized predisposing factors was helpful in identifying which diet was better for whom."

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