TOPLINE: Individuals with overweight and obesity who reach a weight loss plateau at around 6 months on a healthy weight loss diet may not achieve further weight reduction after switching to a different weight loss diet.METHODOLOGY:Dietary and lifestyle interventions initially result in rapid weight loss, followed by a weight loss plateau after a few months and weight regain within a year or two, and diet fatigue has been proposed as a cause but not studied.This secondary analysis of a randomized trial assessed weight loss trajectories before and after switching from a healthy low-carbohydrate (LC) diet to a healthy low-fat (LF) diet (or vice versa) in individuals with overweight and obesity.Overall, 42 participants (mean age, 42 years; 64% women; 87% White individuals) recruited from a local community in Palo Alto, California, were assigned to the LF or LC diet for the first 6 months, after which they were switched to the other diet for the remaining 6 months.Data from the DIETFITS trial, wherein participants remained either on the LF or LC diet for 12 months, were used as historical control.The primary outcome was percent weight change at 3-6 months vs that observed at 6-9 months.TAKEAWAY:The combined average weight loss was 7% (95% CI, 8%-6%) during the first 3 months, declining to 2% (95% CI, 3%-1%) between 3 and 6 months. On switching diets, the weight loss further slowed to 1% (95% CI, 2%-0.4%) between 6 and 9 months, with a modest increase in weight of 0.6% (95% CI, −0.1% to 1.3%) between 9 and 12 months.By diet order, participants in the LF first arm did not plateau and experienced a similar weight loss from 6 to 9 months as they had experienced from 3 to 6 months (relative change, −0.1%; 95% CI, −1.5% to 1.3%), while the LC first arm essentially nullified the 3-6 month weight loss during the 6-9 month LF phase (relative change, 2.2%; 95% CI, 0.7%-3.6%).For the LC first arm, low-density lipoprotein increased at 3 months and decreased when the participants switched to LF at 6 months, whereas the opposite effect was seen for the transition from LF to LC. Triglyceride levels decreased in both intervention arms.Insulin levels decreased in both dietary intervention arms between baseline and 6 months and plateaued following the 6-month dietary switch.IN PRACTICE:”This suggests that the weight loss plateau typically seen at 6 months is physiological and cannot be overcome by simply switching to a different weight-loss diet,” wrote the authors. “As a person transitions from a weight loss to weight maintenance phase, a shift in the approach used may be required.”SOURCE:The study, led by Matthew J. Landry, Stanford Prevention Research Center, School of Medicine, Stanford University, California, was published in Scientific Reports.LIMITATIONS:The study results showed some possible differential trends but also highlighted the small sample size and large variability. Participants may have been unable to provide accurate estimates of self-reported energy intake. The authors also acknowledged that regular physical activity may have contributed to the maintenance of weight loss observed in this study.DISCLOSURES:The study was supported by the Hass Avocado Board; Human Health Service grant (General Clinical Research Centers and National Center for Research Resources, National Institutes of Health); National Heart, Lung, and Blood Institute; and Stanford Diabetes Research Center. The authors declared no conflicts of interest.
https://www.medscape.com/viewarticle/no-added-weight-loss-benefits-switching-healthy-diets-2024a100099x