Time-restricted Eating Not Superior to Traditional Weight Loss Efforts
Time-restricted eating (TRE), also known in the weight loss world as a form of “intermittent fasting,” has become popular in the past few years as the obesity epidemic continues to grow, so to speak.
Previous research indicates that TRE reduces body weight. However, it’s unknown if TRE aids in weight loss independent of calorie reduction, as has been shown in animal studies.
A recent 12-week randomized, calorically-controlled study was published in Annals of Internal Medicine. It included 41 subjects aged 18 to 69 years with obesity and prediabetes, or diet-controlled diabetes. The study used a 10-hour feeding window with 80% of calories eaten before 1 PM or UEP (usual eating pattern) of a <= 16-hour window with half of the calories (at minimum) being eaten after 5 PM.
According to the researchers, the diet was much like the DASH [Dietary Approaches to Stop Hypertension] diet with a bit higher unsaturated fat and micronutrient content.
Study co-author Scott J. Pilla, MD, MHS, an assistant professor of medicine at the Johns Hopkins Bloomberg School of Public Health, Baltimore, noted, “In each participant, macro- and micronutrient content remained constant throughout the study period, with total calories individually determined at baseline and ranging from 1600 to 3500 kcal/day.”
This is different from some TRE studies where calories were adjusted based on whether participants lost or gained weight. This was meant to see the effect of eating time without changes in calories.
While the current research didn’t observe an advantage in weight loss, some data suggests that reducing food intake to a 4 to 10-hour window naturally limits calorie intake by 200-550 calories daily and may result in a weight loss of 3 to 5% of body weight for 2 to 12 months. Metabolic risk factors like insulin resistance have improved with TRE, but this wasn’t the case in this study.
The main outcome in this study was body weight change at 12 weeks. Other outcomes included fasting glucose, homeostatic model assessment for insulin resistance (HOMA-IR), glucose below the curve by oral glucose tolerance test, and hemoglobin A1c.
The study included all 41 subjects with an average age of 69 who finished the intervention. The majority (93%) were women, and 93% identified as African American. The mean BMI was 36 kg/m2. In the TRE group, the baseline weight was 5.6 kg, and 103.7 kg in the UEP group.
Weight dropped by 2.3 kg at 12 weeks in the TRE group and by 2.6 kg in the UEP group. Changes in glycemic measures were not different between the groups. The authors note this was a small, single-site study.
Despite previous research in support of TRE, it did not reduce weight or improve blood sugar levels compared to UEP in this study. This suggests that the impact of TRE on weight in previous research may be related to calorie intake reduction and not meal timing.
However, Krista A. Varady, PhD, and Vanessa M. Oddo, PhD, of the Department of Kinesiology and Nutrition at the University of Illinois Chicago believes TRE may still be beneficial for weight loss. She noted, "Many patients stop following standard-care diets (such as daily calorie restriction) because they become frustrated with having to monitor food intake vigilantly each day".
While TRE wasn’t found to be better than other interventions for weight loss, it’s a simple approach that avoids calorie counting. Instead, they need to watch the clock, Varady notes. She goes on to mention that expensive food isn’t needed and it’s an accessible diet for lower-income individuals.
Support for gastroenterologists is becoming more mainstream as these specialists often treat obesity-related conditions such as fatty liver disease, pancreatitis, and inflammatory bowel diseases.
Michael Camilleri, MD, AGAF, a gastroenterologist at the Mayo Clinic in Rochester, Minnesota suggested in a 2023 post in Gut, "Treating obesity starting when patients present in gastroenterology and hepatology clinics has potential to impact serious consequences of obesity such as cardiovascular risks”.
He goes on to say that GI conditions are being treated by gastroenterologists who could also treat obesity with medication and surgical interventions.
Gastroenterologists already treat GI conditions with pharmacologic and surgical interventions that can also be used to treat obesity and improve glycemic control.
How can you support clients in their weight loss efforts?
· Advise clients of realistic expectations of weight management. There are no magic bullets.
· Discourage fad diets and quick fixes.
· Encourage water over sugar-sweetened beverages, juice, and alcohol.
· Provide recipes for calorie-controlled meals.
· Support high-fiber meals with plenty of produce and plant-based protein.
· Calculate appropriate protein needs. Eating too much won’t help.
· Encourage better sleep hygiene to reduce stress and control cravings.
· Suggest the support of mental health professionals if stress eating is an issue.
· Discourage snacking after dinner.
· Enforce consistent regular cardio and weight training exercises.
Lisa Andrews, MEd, RD, LD
Reference:
Nisa M. Maruthur, MD, MHS, Scott J. Pilla, MD, MHS, Karen White, MS, RDN, Beiwen Wu, MSPH, RDN, May Thu Thu Maw, MBBS, MPH, Daisy Duan, MD, Ruth-Alma Turkson-Ocran, PhD, MPH, APRN and Jeanne M. Clark, MD, MPH Effect of Isocaloric, Time-Restricted Eating on Body Weight in Adults With Obesity: A Randomized Controlled Trial. Annals of Internal Medicine. Volume 177, Number 5