Fiber intake influences the association between variants in TCF7L2 and body weight reduction during a lifestyle intervention and at long-term follow-up
Questions: The extent of weight loss in response to lifestyle intervention (LI) varies considerably between individuals. Gene-diet interactions may explain parts of this difference. The aim of the present study was to evaluate if the TCF7L2 genotype influences the impact of fiber intake on the reduction of body weight during LI and at long-term follow-up. Methods: We studied 187 healthy individuals taking part in the Tübingen Lifestyle Intervention Program (TULIP) in whom long-term follow-up after a mean of 8.7 ± 1.6 years was available. The program consisted of a 9-month combined dietary and exercise intervention. Three-day food diaries were obtained at each of the 10 sessions of dietary counseling. All participants were genotyped for TCF7L2 rs7903146. Results: We obtained two groups, i.e., low and high fiber consumers (LF and HF intake 20.98 ± 0.30 g/day vs. 32.43 ± 0.63 g/day) splitted at median of fiber intake during 9-months of LI. The TCF7L2 non-risk allele carriers consuming high amount of fiber showed a greater weight reduction (-5.67 ± 0.87 kg) than those with LF intake (-1.85 ± 0.59 kg, p = 0.0005). In the risk allele carriers, there was no difference in weight reduction between LF or HF intake (p = 0.2439). At long-term follow-up, only TCF7L2 non-risk allele carriers further lost weight when they consumed a high amount of fiber during LI (-1.14 ± 1.22 kg), whereas those with LF intake regained weight (3.48 ± 1.29 kg, p = 0.0097). Conclusions: Our results show that fiber intake influences weight reduction during a LI as well as long-term weight stabilization only in TCF7L2 non-risk allele carriers. This can help to individualize and optimize such programs.