Perspective: Time-Restricted Eating Compared with Caloric Restriction: Potential Facilitators and Barriers of Long-Term Weight Loss Maintenance

Abstract

A growing body of literature examines the potential benefits of a time-based diet strategy referred to as time-restricted eating (TRE). TRE, a type of intermittent fasting, restricts the time of eating to a window of 4–12 h/d but allows ad libitum intake during eating windows. Although TRE diets do not overtly attempt to reduce energy intake, preliminary evidence from small studies suggests that TRE can lead to concomitant reduction in total energy, improvements in metabolic health, and weight loss. Unique features of the TRE diet strategy may facilitate adherence and long-term weight loss maintenance. In this Perspective, we explore the potential multilevel (i.e., biological, behavioral, psychosocial, environmental) facilitators and barriers of TRE for long-term weight loss maintenance in comparison with the more commonly used diet strategy, caloric restriction (CR). Compared with CR, TRE may facilitate weight loss maintenance by counteracting physiological adaptations to weight loss (biological), allowing for usual dietary preferences to be maintained (behavioral), preserving executive functioning (psychosocial), and enabling individuals to withstand situational pressures to overeat (environmental). However, TRE may also pose unique barriers to weight loss maintenance, particularly for individuals with poor baseline diet quality, internal or social pressures to eat outside selected windows (e.g., grazers), and competing demands that interfere with the scheduling of eating. Future studies of TRE in free-living individuals should consider the multiple levels of influence impacting long-term adherence and weight loss maintenance. Ultimately, TRE could be one strategy in a toolkit of tailored diet strategies to support metabolic health and weight loss maintenance.

Associations between Fasting Duration, Timing of First and Last Meal, and Cardiometabolic Endpoints in the National Health and Nutrition Examination Survey

“…One concern with calorie restriction-based diet programs is weight regain [ 5 , 6 ]. Of growing interest, fasting and other chrononutrition-focused approaches (e.g., consuming a majority of calories early in the morning) have shown potential for improvements in cardiometabolic endpoints, as well as sustainability [ 37 ]. However, most of this work has been conducted in smaller scale intervention studies or pragmatic designs using Ramadan [ 26 ].…”

“…This makes parsing out the effect of TRF from calorie restriction difficult. [ 37 , 38 ]. For example, a review found that 9 of 11 studies comparing some form of IF to continuous calorie restriction found similar effects on weight reduction.…”

“…The fasting group with energy restriction had decreased total body mass and fat mass, but such reductions among the fasting group without energy restriction was not observed [ 40 ]. Regardless, much of the evidence related to TRF and cardiometabolic health have been in the form of highly controlled RCTs of short duration or pragmatic designs using religious fasting [ 36 , 37 ].…”

“…Given that prior TRF work may be biased by inherent calorie restriction, it was broadly theorized that usage of a population-based study, such as the National Health and Nutrition Examination Survey (NHANES), would be able to assess the association between fasting and cardiometabolic markers without overlapping calorie restriction as most people are not actively dieting or specifically cutting calories [ 37 , 38 ]. Additionally, a larger population, especially a population such as NHANES, leads to greater power to detect associations.…”

Time-Restricted Eating Improves Quality of Life Measures in Overweight Humans

“…As TRE has increased in popularity in the last decade, its ability to maintain long-term weight loss has not been studied, though it has been hypothesized that the simplified approach of TRE may be easier to sustain than traditional calorie restriction as it is a simplified way of eating that allows for ad libitum intake during a specific time window and does not require time-consuming calorie counting [ 13 ]. If TRE and associated weight loss can be demonstrated to improve quality of life (QoL), presumably this would facilitate adherence, though the relationship between weight loss and QoL is unclear.…”