Effect of Time-restricted Eating on Behaviour and Metabolism in Overweight Individuals at High Risk of Type 2 Diabetes

The aim of the present study is to investigate effects of 12 weeks time-restricted eating on behaviour and metabolism in individuals with overweight or obesity at high risk of type 2 diabetes.

Overweight and obese individuals with pre-diabetes or with a family history of diabetes or cardiovascular disease (CVD) are at high risk for developing type 2 diabetes (T2D) and CVD. Current prevention and treatment of obesity and T2D include energy restricted diets and increased levels of physical activity; however, adequate adherence to such strategies is difficult, and maintenance is challenging for most individuals, which stresses the need for feasible and sustainable interventions.

Circadian rhythms of behaviour and metabolism are closely related to the daily light/dark cycle and sleep-wake patterns and timing of food intake and fasting periods may affect the circadian rhythms of metabolic organs. In an evolutionary perspective, the pattern of food consumption has been characterised by periods of caloric intake when food was available and subsequent periods of fasting 9. This cyclic pattern leads to cycles of absorption and storage of energy and utilisation of the energy for e.g. tissue repair, stress resistance and vitality where expression of metabolic regulators coordinates with cellular processes, leading to efficient metabolism 10. Factors including the 24-hour availability of energy-dense foods, busy time schedules, different eating and sleep patterns during weekdays and weekends (i.e. 'social jetlag') challenge the feeding-fasting paradigm. Recent data suggest that an erratic diurnal eating pattern characterised by food intake largely spread throughout hours awake (≥15 h) and a concomitant short fasting period is highly prevalent in humans and animal suggest that circadian misalignment of food intake is associated with adverse metabolic effects. A number of animal studies and a few small studies in humans have reported promising effects of time-restricted eating (TRE), without concomitant dietary restrictions, on body weight and other cardiometabolic risk factors. There is a lack of randomized controlled trials investigating effect of TRE in individuals at high risk of type 2 diabetes and cardiovascular diseases.

The aim of the present study is to investigate effects of 12 weeks TRE on behaviour and metabolism in individuals with overweight or obesity at high risk of type 2 diabetes. Maintenance will be assessed at a follow-up visit 13 weeks after completion of the trial (26 weeks). Testing will be conducted at baseline and after 6, 12, and 26 weeks. Participants are instructed to follow randomization during one week assessment periods after testing at 6 and 12 weeks. Therefore, the total duration of the intervention is 13 weeks.

Eligibility Criteria:
Inclusion Criteria:

* BMI ≥30 kg/m2 or BMI ≥25 kg/m2 in combination with pre-diabetes (HbA1c ≥39-\<48 mmol/mol)
* Habitual eating/drinking window ≥12 hours (including foods/snacks and energy containing beverages e.g. soft drinks (except of water)) and an eating/drinking window of ≥14 hours minimum one day per week

Exclusion criteria

* Daily smoking
* For women: pregnancy, planned pregnancy (within the study period) or lactating
* Frequent travels over time zones (max one return trip/travel over times zones (˃one hour time difference) during the 13 weeks intervention).
* Shift work or partner engaged in shift work (if it affects the person's sleep and eating pattern)
* Unable to understand the informed consent and the study procedures
* Self-reported history of an eating disorder during the past three years
* Self-reported weight change (\>5 kg) within three months prior to inclusion
* Diabetes
* HbA1c ≥48 mmol/mol
* Uncontrolled medical issues including but not limited to cardiovascular pulmonary, rheumatologic, hematologic, oncologic, infectious, gastrointestinal or psychiatric disease; diabetes or other endocrine disease; immunosuppression
* Current treatment with medication or medical devices which significantly affect glucose metabolism, appetite, or energy balance
* Current treatment with antidepressants
* Bariatric surgery
* Implanted or portable electro-mechanical medical device such as a cardiac pacemaker, defibrillator or infusion pump
* Celiac disease, Crohn's disease, ulcerative colitis or proctitis
* Alcohol/drug abuse or in treatment with disulfiram at time of inclusion
* Concomitant participation in other intervention studies
* Not able to eat ≥85% of the test meal because of e.g. allergy

Specific exclusion criteria for participants receiving SmartPillTM (n=60)

* Gastrointestinal symptoms or diseases such as regular (weekly) abdominal pain, dysphagia, gastric bezoars, strictures, fistulas, bowel obstructions or diverticulitis
* Current treatment with medication or medical devices which significantly affect gastrointestinal motility or transit time (prokinetics, antidiarrheals, laxatives, or opioids)
* Gastrointestinal surgery within 3 months before inclusion