The Impact of Time-Restricted Diet on Sleep and Metabolism in Obese Volunteers

Abstract

Background and objectives: A time-restricted diet is one of the various ways to improve metabolic condition and weight control. However, until now, there have been few pieces of evidence and research to verify the methods and effectiveness of time-restricted diets on metabolic improvement and health promoting. We designed this study to make a healthy diet program and to verify the effectiveness of a time-restricted diet on general health, including sleep and metabolism, in healthy volunteers. Materials and Methods: This study was conducted in healthy adults who are obese but do not have related metabolic disease. Fifteen participants were recruited. Before and after this program, serologic tests including ketone level, questionnaires—daytime sleepiness evaluation such as the Epworth sleepiness scale and the Stanford sleepiness scale, the Korean version of the Pittsburgh sleep questionnaire index, STOP BANG to evaluate sleep apnea, the Hospital Anxiety and Depression Scale for emotion/sleep—and polysomnography (PSG) were conducted to evaluate the effects on sleep of the program. They were divided into two groups based on ketone levels that could reflect the constancy of participation in this study. We analyzed the before and after results of each group. Results: Fifteen participants (nine males and six females) completed this program without significant adverse events. Body weight after this program decreased to 78.2 ± 14.1 from 82.0 ± 15.6 kg (p = 0.539), and BMI decreased to 27.9 ± 3.8 from 29.3 ± 4.6 kg/m2 (p = 0.233). Weight loss was observed in 14 subjects except 1 participant. The results from questionnaires before and after this were not significant changes. They were classified into high/low-ketone groups according to the ketone level of the participants. In the results of the PSG, the apnea hypopnea index (25.27 ± 12.67→15.11 ± 11.50/hr, p = 0.25) and oxygen desaturation (18.43 ± 12.79→10.69 ± 10.0/hr, p = 0.004), which are indicators of sleep apnea, also improved in the high-ketone group, compared with the low-ketone group. Satisfaction interviews for this restricted diet program showed that 86% of the participants were willing to participate in the same program again. Conclusion: The time-restricted diet was successful in weight loss for a period of 4 weeks in obese participants, which did not affect the efficiency and architecture of sleep. In addition, successful weight loss and significant improvement of sleep apnea were showed in the high-ketone group. Further research is needed to demonstrate mechanisms for weight loss, sleep apnea, and time-restricted diets.

A randomized controlled trial to compare the effects of time-restricted eating versus Mediterranean diet on symptoms and quality of life in bipolar disorder

“…Other work has shown benefits of TRE compared to a control condition for quality of life [ 68 , 69 ]. Uncontrolled studies of TRE have shown no significant decrease in pre- to post-depression scores [ 70 , 71 ], although low depressive symptom levels at baseline might help explain these inconsistent findings.…”

Meal Timing and Sleeping Energy Metabolism

“…Time-restricted eating did not affect quality of sleep, as assessed by the Pittsburgh Sleep Quality Index (PSQI) [ 4 , 32 , 33 , 34 , 35 , 36 ]. Considering that the percentage of calories consumed after 20:00 is 19.9% on average [ 4 ], all time-restricted eating studies shifted the end of the eating window to earlier than that of the control condition.…”

Nutritional Elements in Sleep

“…Time-restricted eating entails consuming the major portion of one’s daily calorie intake within a limited window of time, which is considered an effective weight-loss strategy. However, aside from the indirect effect it has on sleep through mitigating obesity, it is also shown to positively affect sleep outcomes [ 47 , 42 ] independent of it causing weight loss and improving cardiometabolic health [ 35 , 43 ].…”