Adherence, not diet type, strong predictor for weight-loss success

December 04, 2021

3 min read


Ryan D. What’s the best weight loss diet. Presented at: World Congress on Insulin Resistance, Diabetes & Cardiovascular Disease; Dec. 2-4, 2021; Los Angeles (hybrid meeting).

Ryan reports serving as an adviser or consultant for Altimmune, Amgen, Calibrate, Epitomee, Gila Therapeutics, IFA Celtic, Lilly Advisory, Naturally Slim, Novo Nordisk, Pfizer, Real Appeal, Ro, Scientific Intake, Wondr Health, Xeno Bioscience and YSOPIA, and serving on the speakers bureau for Novo Nordisk, having an ownership interest in Calibrate, Epitomee, Gila Therapeutics, Roman, Scientific Intake and Xeno Bioscience, and receiving research support from the SELECT Steering committee.

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Multiple dietary pathways can lead to weight loss, and adherence to a weight-loss program is a better predictor for success than the type of eating pattern a person chooses, according to a speaker.

“Every diet is associated with great variation in weight-loss success, and adherence to the diet is the best predictor of success,” Donna H. Ryan, MD, professor emerita at Pennington Biomedical Research Center in Baton Rouge, Louisiana, told Healio. “However, even though we recommend that the choice of the diet involve the patient, there is no evidence that diets based on choice vs. no choice produce greater weight loss. The quality of the diet is important in health improvement.”

Key takeaways for choosing a weight-loss program: Diets should be based on a patient’s preference and health status. Adherence is the strongest predictor for weight loss. Dietary quality is as important as caloric intake.

Ryan discussed weight-loss diets at the World Congress on Insulin Resistance, Diabetes & Cardiovascular Disease.

Diet adherence associated with weight loss

Research has not found any diet to be best for weight loss. In data published in Obesity in 2013, an expert panel reviewed literature from 17 diets and found no diet was clearly superior to the others for weight-loss duration of at least 1 year. Rather than endorse a specific diet, guidelines instructed providers to reduce calories to 1,200 kcal to 1,500 kcal per day for women and 1,500 kcal to 1,800 kcal per day for men. Additionally, the guidelines stated diets should be based on a patient’s preference and health status.

Donna Ryan

Donna H. Ryan

Multiple studies have found diet adherence is associated with weight loss. A 2005 study published in JAMA analyzed weight change for adults on the Atkins, Zone, WW and Ornish diets. There was no difference in weight change by diet type, but adherence to any diet for a longer period of time was associated with greater weight loss.

Ryan highlighted three popular diets associated with health benefits: time-restricted eating, clean eating and a ketogenic eating pattern. Time-restricted eating involves consumption during a window of about 6 hours per day and an extended fast of 18 hours. The clean eating diet has participants avoid processed foods. Those who follow a ketogenic diet consume about 75% fat, 20% protein and 5% carbohydrates.

There are benefits to all three diets, Ryan noted, but all three also have variations in response.

“Not all people will succeed with any one of these diets,” Ryan said. “In addition, early time-restricted eating is associated with increased triglycerides, and the ketogenic diet has been associated with low blood pressure, kidney stones, constipation and nutrient deficiencies.”

Ryan said there is a lot of interest in personalized diets based on genetic and phenotypic profiles. However, although the NIH is planning to fund studies to examine weight-loss efficacy for personalized diets, no evidence has so far demonstrated that phenotyping can improve dietary response.

“Some companies have emerged purporting to tailor ‘personalized diets,’” Ryan said. “This approach has inherent appeal; it would be great if we could identify subsets of individuals who respond well to this dietary approach. But, thus far, the gene variants associated with better response to certain diets are associated with only small effect size and may be contradictory.”

A personalized approach to weight-loss diets

The only eating pattern with clinical trial data available is the Mediterranean diet. In a study published in The New England Journal of Medicine in 2018, participants following a Mediterranean diet had a lower risk for acute myocardial infarction, stroke or cardiovascular disease death compared with those on a control diet.

Ryan discussed several approaches health care professionals should take when caring for patients who are dieting. Low-carb or low glycemic index diets are advised for people with diabetes or prediabetes. Providers should respect a patient’s choice of diet for weight loss and focus on dietary adherence. Although caloric intake is important, dietary quality is key, and providers should make sure any long-term diet is health-promoting.