Pavlou V, Cienfuegos S, Lin S, et al. Effect of Time-Restricted Eating on Weight Loss in Adults With Type 2 Diabetes: A Randomized Clinical Trial. JAMA Netw Open. 2023 Oct 2;6(10):e2339337. doi: 10.1001/jamanetworkopen.2023.39337. (Original study)

IMPORTANCE: Time-restricted eating (TRE) has become increasingly popular, yet longer-term randomized clinical trials have not evaluated its efficacy and safety in patients with type 2 diabetes (T2D).

OBJECTIVE: To determine whether TRE is more effective for weight reduction and glycemic control than daily calorie restriction (CR) or a control condition in adults with T2D.

DESIGN, SETTING, AND PARTICIPANTS: This 6-month, parallel-group, randomized clinical trial was performed between January 25, 2022, and April 1, 2023, at the University of Illinois Chicago. Participants were aged 18 to 80 years with obesity and T2D. Data analysis was based on intention to treat.

INTERVENTIONS: Participants were randomized to 1 of 3 groups: 8-hour TRE (eating 12 to 8 pm only, without calorie counting), CR (25% energy restriction daily), or control.

MAIN OUTCOMES AND MEASURES: The primary outcome measure was change in body weight by month 6. Secondary outcomes included changes in hemoglobin A1c (HbA1c) levels and metabolic risk factors.

RESULTS: Seventy-five participants were enrolled with a mean (SD) age of 55 (12) years. The mean (SD) body mass index (calculated as weight in kilograms divided by height in meters squared) was 39 (7) and the mean (SD) HbA1c level was 8.1% (1.6%). A total of 53 participants (71%) were women. One participant (1%) was Asian, 30 (40%) were Hispanic White, 40 (53%) were non-Hispanic Black, and 4 (5%) were non-Hispanic White. Participants in the TRE group were adherent with their eating window on a mean (SD) of 6.1 (0.8) days per week, and 17 (68%) in the CR group were adherent with their prescribed calorie goals over 6 months. The mean (SD) reduction in energy intake was -313 (509) kcal/d for TRE, -197 (426) kcal/d for CR, and -16 (439) kcal/d for controls. By month 6, body weight decreased significantly in the TRE group (-3.56% [95% CI, -5.92% to -1.20%]; P = .004) but not the CR group (-1.78% [95% CI, -3.67% to 0.11%]; P = .06), relative to controls. Levels of HbA1c decreased in the TRE (-0.91% [95% CI, -1.61% to -0.20%]) and CR (-0.94% [95% CI, -1.59% to -0.30%]) groups, relative to controls, with no differences between the TRE and CR groups. Time in euglycemic range, medication effect score, blood pressure, and plasma lipid levels did not differ among groups. No serious adverse events were reported.

CONCLUSIONS AND RELEVANCE: This randomized clinical trial found that a TRE diet strategy without calorie counting was effective for weight loss and lowering of HbA1c levels compared with daily calorie counting in a sample of adults with T2D. These findings will need to be confirmed by larger RCTs with longer follow-up.

TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT05225337.

Discipline Area Score
Internal Medicine 7 / 7
Family Medicine (FM)/General Practice (GP) 6 / 7
General Internal Medicine-Primary Care(US) 6 / 7
Endocrine 5 / 7
Comments from MORE raters

Endocrine rater

These results support the dictum that calories do count. From a clinical perspective, limiting the amount of time patients are allowed to eat reduces their caloric intake, by 313 kcal/day in this study. The calorie-restricted group reduced their caloric intake by only 197 kcal/day. Since it takes a 3500 kcal deficit to lose 1 lb of fat, this difference between the 2 groups theoretically results in a 2.7kg difference in weight loss. One needs at least a 5% reduction in body weight to have a clinically beneficial effect, and this study supports this as there was no difference in A1c, TIR, or other clinical outcomes. Bottom line: time-restricted eating may limit some caloric intake, but so far this approach has little clinical impact.

Endocrine rater

Well conducted RCT providing useful information regarding benefits of time-restricted eating for patients with T2D. It is interesting that weight loss was greater, but there was no difference in glycemic control. Larger studies are needed to confirm these findings.

Family Medicine (FM)/General Practice (GP) rater

Promising findings of small additional weight loss in the time-restricted eating group over the calorie-restricted group, but HbA1c reductions were similar. There was higher compliance with the intervention in the first vs second intervention, which may have explained its effectiveness. A larger and longer RCT is needed to confirm these findings.

General Internal Medicine-Primary Care(US) rater

A small but interesting study.

General Internal Medicine-Primary Care(US) rater

This trial of 75 overweight patients (BMI 38) with T2DM lasted 6 months. It showed that time-restricted eating (8 hours of unrestricted consumption and 16 hours of fasting) was slightly superior to calorie-restricted eating. They clearly stated that they need a trial of more patients that lasts longer to determine the true effectiveness of time-restricted eating.

Internal Medicine rater

In primary care we are always looking for lifestyle methods that are safe, easy to understand for patients, and effective. Time-restricted eating (TRE) or intermittent fasting has been trendy as a fad diet for a while now. People with diabetes are understandably curious about the safety around it when they see many experience weight loss. This article supports the idea that, at least in the short term, TRE is tolerable and sustainable and may be more palatable given the lack of calorie counting involved. This is a small study that is heavily weighted toward females, so it is difficult to generalize to others. At least it provides good news to interested parties for a viable option for weight control.
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