Weight loss over 12 months was substantially the same between adults assigned to a healthy low-fat diet or a healthy low-carbohydrate diet, according to findings published in JAMA.
Further, genotype pattern and baseline insulin secretion were not associated with the dietary effects on weight loss, according to the researchers.
Christopher D. Gardner, PhD, of the Stanford Prevention Research Center, department of medicine at Stanford University Medical School, and colleagues evaluated data from the Diet Intervention Examining the Factors Interacting With Treatment Success (DIETFITS) on 609 adults (mean age, 40 years; 57% women; mean BMI, 33 kg/m2; 40% with low-fat genotype; 30% with low-carbohydrate genotype) to determine effects of diet composition on weight change over 12 months. Researchers also examined whether and genotype pattern or insulin secretion are related to the dietary effects on weight loss.
Participants were randomly assigned to the 12-month healthy low-fat diet (n = 305) or healthy low-carbohydrate diet (n = 304); both diets were delivered by health educators during 22 diet-specific small group sessions that focused on methods for achieving the lowest fat or carbohydrate intake. Researchers also sought to determine whether three single-nucelotide polymorphism multilocus genotype responsiveness patterns (PPARG, ADRB2 and FABP2), which have been considered to predispose one to respond to a low-fat or low-carbohydrate diet, or insulin secretion (INS-30; blood concentration of insulin 30 minutes after a glucose challenge) were associated with weight loss; mean INS-30 was 93 µIU/mL in all participants.
In the healthy low-fat diet group, 42.6% of participants had the low-fat responsiveness genotype, and 27.2% had the low-carbohydrate responsiveness genotype. In the healthy low-carbohydrate diet group, 37.5% had the low-fat genotype and 31.9% had the low-carbohydrate genotype.
No significant differences were observed between the two groups for mean 12-month weight changes (low-fat diet group, -5.3 kg vs. low-carbohydrate diet group, -6 kg).
No significant interaction was observed between diet-genotype pattern or diet-insulin section with 12-month weight loss.
Seven serious adverse events and 11 adverse events occurred during the trial with equal distribution between the two groups.
“In this 12-month weight-loss diet study, there was no significant difference in weight change between a healthy low-fat diet vs. a healthy low-carbohydrate diet, and neither genotype pattern nor baseline insulin secretion was associated with the dietary effects on weight loss,” the researchers wrote. “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.” – by Amber Cox
: The authors report no relevant financial disclosures.