As per the studies, 1 out of 8 are living with obesity and 43% of the population is overweight. Overweight and obesity increases the risk of developing type 2 diabetes mellitus, coronary heart diseases, certain cancers, and all causes mortality. Dietary therapy is one of the three components of treatment of obesity and shows such intervention as lowering energy intake or changing fat to carbohydrates ratio or a diet.
Keeping to this approach for a long period of time proves to be a quite demanding challenge for many overweight people trying to lose weight with diet. On the one hand, restricting the calories consumed every day is the basic principle of any diet, which inevitably raises the need for meal timing strategies (i.e., ‘which refers to the temporal distribution of meals within a given day’, which includes but is not limited to eating windows and meal frequency, distributions and patterns) such as time-restricted feeding (TRF) or its less extreme forms (like composing calorie content of meals instead of restricting quantities) to those who even have difficulties with straightforward continuous energetic restriction basing word and meal counting for hundreds of men. To find out these points, A systematic review and meta-analysis published in JAMA network.
This systematic review was carried out following the Cochrane approach and the PRISMA guidelines for reporting systematic reviews and meta-analyses. In addition, this intervention was registered with PROSPERO prior to commencement (CRD42023474391).
The Bond University, Human Research Ethics Committee, exempted this study from approval and informed consent due to the unobtrusive nature of the study, which only analyzed publicly available data from published findings.
Authors incorporated RCTs with individuals aged 18 years and above, healthy or with other illnesses and the association between the temporal distribution of isocaloric meals adjusted to the biological day (TRE, frequencies of meals, and calories distribution, etc.) and weight / body mass index (BMI – weight in Kilograms divided by height in meters squared) gained over a period of 12 weeks or longer were assessed.
Considering the inclusion criteria, any study that had participants suffering from anorexia or bulimia, individuals who had undergone obesity surgery, or pregnant females was omitted. Non-RCTs and observational studies were also removed from the primary research. Major outcomes and measures are weight change in kilograms, reported as between-group mean difference with 95% CIs.
Sixty-nine reports of 29 randomized clinical trials including 2485 individuals (1703 [69%] female; mean [SD] age, 44 [9.5] years; and mean [SD] body mass index, 33 [3.5]) were included. Study interventions included TRE (17 studies), meal frequency (8 studies), and calorie distribution (4 studies). There were some concerns of risk of bias for 7 studies and high concerns for 22 studies.
Statistically significant weight change was observed in TRE when compared with control (–1.37 kg; 95% CI, –1.99 to –0.75 kg). Lower meal frequency and earlier caloric distribution were also both associated with greater change (–1.85 kg; 95% CI, –3.55 to –0.13 kg; and –1.75 kg; 95% CI, –2.37 to –1.13 kg, respectively).
This study has several drawbacks. First, most studies recruited participants from clinical settings and employed nutrition-trained clinicians, which could reduce the applicability of findings. In addition, all studies focused on calorie distribution included only females, thus restricting the extent of generalization to male subjects.
Second, low-risk of bias and inconsistency contributed to the low overall level of quality of evidence. Most of the studies included in this review were rated high risk owing to the inability to blind dietary interventions and the reliance on self-reported outcome assessment. We acknowledge the limitations of this analysis due to the high level of heterogeneity, which was somewhat addressed through subgroup analyses.
In this meta-analysis it was stated that TRE, lower meal frequency or eating more calories in the earlier hours of the day led to a slight weight loss and better metabolic function. The sizes of the effects were small, yet these strategies might be reasonable for a long term weight maintenance.
Reference: Hiu Yee Liu et al, Meal Timing and Anthropometric and Metabolic Outcomes, JAMA Network Open (2024).
