Metabolic Health
Conditions
Keywords
chrononutrition, metabolism, body composition
Brief summary
In the modern era, food access is widely available and it is not uncommon for the time between breakfast and a late night snack to exceed 14 hours. The investigators are interested in studying whether limiting this window to 8 hours will have any beneficial effects of human health as has been demonstrated in animal models. Eight men were asked to restrict their energy intake window to between 8 am and 4 pm for two weeks whilst maintaining their habitual diet (quantity and composition). Improvements in skeletal muscle and whole-body insulin sensitivity were observed but these were potentially confounded by an average weight loss of 1 kg. Therefore an additional control group was recruited to follow a daily caloric deficit of \ 400 kilocalories without changing the timing of intake.
Detailed description
All participants were monitored for a one week baseline period to establish their habitual physical activity and dietary patterns. This was done using food diaries, interstitial glucose monitors and a combined heart rate + accelerometer device. Participants consumed a standardised evening meal \ 12h before visiting the laboratory to assess their metabolic response to a liquid test meal (1g/kg bodyweight dextrose and 0.4g/kg bodyweight protein) using the arterio-venous forearm balance model. Dual-energy X-ray absorptiometry scans, indirect calorimetry measurements and fasted and postprandial vastus lateralis biopsies were also obtained. From the next day, participants either restricted their daily energy intake window to between 8 am and 4 pm or were prescribed a caloric deficit diet (\ 400 kilocalories/day) for two weeks. Physical activity, interstitial glucose concentrations and dietary patterns were monitored throughout. After this, participants visited the laboratory again to assess changes in metabolism and body composition.
Interventions
BEHAVIORALTime restricted feeding
Restrict energy intake window to between 8am and 4pm
BEHAVIORALCaloric restriction
Follow a prescribed daily energy deficit of 400 kilocalories without altering nutrient timing
Sponsors
University of Nottingham
Study design
Allocation
NON_RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
NONE
Intervention model description
All participants monitored for a one week baseline period before being allocated to either a caloric deficit group or a time-restricted feeding group for two weeks.
Eligibility
Sex/Gender
MALE
Age
18 Years to 35 Years
Healthy volunteers
Yes
Inclusion criteria
* Healthy male between 18 and 35 years old * Body mass index between 18 and 27.5 kg.m\^-2 * Regular breakfast consumer, 5 or more days per week * Moderate physical activity level (PAL between 1.6 and 2)
Exclusion criteria
* Smoking * Any metabolic (e.g. diabetes), endocrine (e.g. hyperthyroidism) or cardiovascular (heart or blood) abnormalities including hypertension. * Clinically significant abnormalities on screening including ECG abnormalities * Routine medication that may alter cardiovascular function and blood flow (e.g. blood pressure-lowering drugs or drugs that cause hypertension) * High alcohol consumption (Routinely \>4 units per day) * Eating attitudes test (EAT-26) score \> 20 * On an energy-restricted diet * Significant body mass fluctuation in previous 3 months (\>5%)
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in glucose uptake | Pre and post intervention (15 days apart). Fasted blood samples and every 10 min for 3 hours following consumption of carbohydrate + protein drink | The arterio-venous forearm balance method was used to assess skeletal muscle glucose uptake in micromoles/min. |
| Change in branched chain amino acid uptake | Pre and post intervention (15 days apart). Fasted blood samples and every 10 min for 3 hours following consumption of carbohydrate + protein drink | The arterio-venous forearm balance method was used to assess skeletal muscle branched chain amino acid uptake in micromoles/min. |
| Change in whole-body insulin sensitivity | Pre and post intervention (15 days apart). | The Matsuda Index was used to calculate an index of whole-body insulin sensitivity using values of fasted and postprandial glucose and insulin. Measured in arbitrary units and higher values indicates increased insulin sensitivity. All individual changes will be reported. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change in body composition | Pre and post intervention (15 days apart) | Dual-energy X-ray absorptiometry scans to assess changes in fat mass in kg |
| Change in substrate metabolism | Pre and post intervention (15 days apart). In each condition there was one measurement in the fasted state and two measurements in the postprandial state. | Rates of oxygen consumption and carbon dioxide production were measured using indirect calorimetry. These were used to calculate rates of fat and carbohydrate metabolism in grams/min. |
Countries
United Kingdom
Outcome results
None listed