5MinuteConsult Journal Club

Time Restricted Dieting: STILL Not the Answer

References

Journal of Clinical Endocrinology & Metabolism, dgac570, https://doi.org/10.1210/clinem/dgac570

Cell Metabolism 34, 1457–1471; https://doi.org/10.1016/j.cmet.2022.09.003

Study Summary

Systematic review and meta-analysis of time restricted eating; included 17 RCT’s of adults which lasted at least 4 weeks. Most used a 16 hour of fasting time frame, leaving 8 hours per day for eating. An exercise component was not required for inclusion.

Mean weight loss was -1.6 kg (95% CI -2.27—0.93) with mean fat mass reduction of -1.48 (95% CI -1.59 – 1.38). It also has small, clinically insignificant reductions in triglycerides (12.71 mg/dl), total cholesterol (-6.45 mg/dl) and LDL (-7.0 mg/dl). There were no benefits found in reduction in waist circumference, BMI, A1c, or blood pressure.

Conclusions

Time restricted eating (TRE) alone provides very small improvements in weight loss while people maintain the time restriction.

Discussion

This study speaks volumes about the limited benefit of TRE. Like most other forms of dieting, it is a small stop gap. The body adjusts to circumstances; eating all you want in a short time frame may lower those late-night snacks, but it does not seem to alter outcomes that are clinically important. Since this form of eating, like a “Keto” diet, is difficult to maintain over time, one wonders if outcomes a year after these studies ended would show weight gain.

A recent trial of TRE combined with High Intensity Interval Training (TRE-HIIT) was effective at improving Hbg A1c levels, total weight loss and fat mass loss (Cell Metabolism 34, 1457–1471; https://doi.org/10.1016/j.cmet.2022.09.003).

A dietician I know states the secret to weight loss is to EAT MORE of the good stuff, like fruits, vegetables, and whole grains (not “whole wheat”) foods and less processed and artificial foods, with adequate protein at every meal.

The future of weight loss needs to focus itself on lifelong dietary change, combined with both aerobic and anaerobic exercise. There is no secret here.

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