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.
A version of this article first appeared on Medscape.com.