A University of California, Irvine-led study determined that dietary changes from one plan to another are a key reason that individuals can maintain previous weight loss and continued weight loss versus any psychological changes – over a 12-month period.
Researchers found that adults who ate a healthy low-fat or low-carbohydrate diet for six months initially experienced rapid weight loss but eventually plateaued, which can be problematic for long-term diet interventions.
The study findings, led by corresponding author, Matthew Landry, PhD, RDN, assistant professor of population health and disease prevention at UC Irvine’s Program in Public Health, are published in the Nature journal Scientific Reports.
Results suggest that the weight loss plateau typically seen at six months is physical and cannot be overcome by simply switching to a different weight-loss diet alone, but that new approaches to continued weight loss and maintenance are needed.
Preventing and combatting obesity has remained a difficult public health challenge. According to 2017–2018 data from the National Health and Nutrition Examination Survey, 42% of adult Americans are considered obese. Furthermore, obesity is a leading risk factor for many chronic diseases, making weight management an important diet and lifestyle intervention.
We need to shift our approach because strategies that were most effective for weight loss may not be the same strategies that guide successful weight maintenance.”
Matthew Landry, PhD, RDN, FAND
Using a randomized, cross-over study design, Landry and colleagues monitored a group of 42 adults over 12 months where each group followed either a healthy low-fat or healthy low-carbohydrate diet for the first half of their year timeline. At the halfway point, the two groups switched to the opposite diet for an additional six months. Regardless of their diet assignment, participants experienced rapid initial weight loss in the first three months but slowed between three to six months. After switching diets at six months, weight modestly decreased until nine months, but at a slower rate than the first half of the timeline.
“We suspect that a weight loss plateau is triggered because an individual grows tired of a certain diet and the weariness overshadows the weight loss itself, suggesting that diet fatigue sets in, and with it, negative habits can come back,” Landry said.
Additionally, as an individual loses weight, the number of calories that our bodies burn while at rest also decreases because there is less mass to support. At the same time, the body also responds to weight loss by increasing appetite-stimulating hormones like ghrelin, gastric inhibitory polypeptide, and pancreatic polypeptide.
Landry added, “as a person transitions from a weight loss to weight maintenance phase, we need to shift our approach because strategies that were most effective for weight loss may not be the same strategies that guide successful weight maintenance.”
Future interventions that weave in the cognitive and emotional aspects or perceived structural support systems can be effective as they largely influence weight-management success. Together, researchers and clinicians must continue to work together to discover new ways to promote longer-term dietary adherence and maintenance of weight loss.
Additional study authors include Priya Fielding-Singh from the Sandberg Goldberg Bernthal Family Foundation and Catherine Ward, Kristen M. Cunanan, Christopher D. Gardner, and Anthony Crimarco all from Stanford University.
This study was supported in part by the Hass Avocado Board and by Human Health Service grant no. M01-RR00070, General Clinical Research Centers, National Center for Research Resources, NIH; the National Heart, Lung, and Blood Institute grant no. T32HL007034; and partially supported by the Quantitative Sciences Unit through the Stanford Diabetes Research Center, grant no. P30DK116074.
