Abstract
BACKGROUND AND AIM: Telomere length (TL) is a key biomarker of cellular aging, with shorter telomeres associated with age-related diseases. Lifestyle interventions mitigating telomere shortening are essential for preventing such conditions. This study aimed to examine the effects of two weight loss dietary strategies, based on a moderately high-protein (MHP) diet and a low-fat (LF) diet on TL in individuals with overweight or obesity. METHODS AND RESULTS: A total of 164 participants, aged 18-65 years from the OBEKIT trial received the MHP (n = 83) or the LF diet (n = 81) for 4 months and had TL data for analyses. TL was measured at baseline and after 4 months of the intervention using monochrome multiplex quantitative polymerase chain reaction (MMqPCR). Both groups experienced significant improvements in anthropometric and biochemical parameters after the dietary intervention (p < 0.001). The MHP group showed an increase in TL (+0.16 ± 0.13) compared to the LF group (-0.05 ± 0.13) in multiple-adjusted models (p = 0.016). An interaction was observed between the sex and dietary group, where women in the MHP group had increased TL (+0.23 ± 0.16) after 4 months compared to women in the LF group (-0.13 ± 0.15; p = 0.001); no differences between dietary groups were found in men. This increase in TL for women was associated with an increase in protein intake (p = 0.006), measured through dietary questionnaires. CONCLUSION: This study shows that a MHP diet may have a protective effect on TL during weight loss, particularly in women, potentially contributing to healthier aging. These results highlight the importance of considering macronutrient composition in dietary interventions aimed at preserving TL.