Glucose and Lipid Metabolism
Conditions
Keywords
carbohydrate restriction, fasting, intermittent energy restriction
Brief summary
Most individuals spend the majority of the day in a fed state, making postprandial blood glucose and lipid regulation a central component of metabolic health. Short periods of fasting or reduced carbohydrate intake can occur frequently in daily life, whether through intentional dietary practices (e.g. intermittent fasting), cultural or religious traditions, or unstructured eating patterns. These periods can induce measurable metabolic changes, but the acute effects of a single 24-hour period of fasting or carbohydrate restriction on postprandial metabolism upon refeeding remain poorly characterised. This study will examine how 24 hours of either complete fasting or low carbohydrate intake without energy restriction influence postprandial blood glucose and lipid concentrations, as well as related metabolic markers, in healthy adults, in comparison to a habitual high carbohydrate control diet. Participants will complete all three conditions in a randomised order, consuming a standardised meal test after each 24-hour condition. Repeated blood sampling and gas exchange measurements will be carried out to assess postprandial metabolic responses. The aim of this study is to characterise whether acute periods of fasting and low carbohydrate restriction elicit distinct or comparable alterations in postprandial metabolic responses. A clearer understanding of these acute physiological effects can help inform how variations in eating patterns influence glucose and lipid handling in individuals without metabolic disease.
Interventions
BEHAVIORALFasting
No food intake for 24 hours
BEHAVIORALCarbohydrate restriction
Restriction of dietary carbohydrate to ≤5% of total energy intake for 24 hours
Sponsors
University of Bath
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 40 Years
Healthy volunteers
Yes
Inclusion criteria
* Aged between 18-40 years * Have a BMI of 18.5-29.9 kg/m2
Exclusion criteria
1. Diagnosed with any major chronic conditions (e.g. type 2 diabetes, coronary heart disease, cancer, chronic kidney disease, etc.) 2. Use of medication that may interfere with study outcomes (e.g. glucose or lipid-lowering medications) 3. Currently or recently pregnant (within last 6 months), planning to get pregnant or currently lactating 4. Has a habitually low carbohydrate intake (\<150g carbohydrates/day) 5. Current or previous eating disorder 6. Has donated more than 500ml of blood in the last 3 months prior to the initial laboratory visit 7. Insufficient mental capacity or language skills to independently understand and follow the study protocol 8. Has an irregular sleeping pattern (e.g. due to undertaking night-shift work) 9. Any other condition, concurrent intervention or behaviour deemed either to pose undue personal risk to the participant or to introduce bias into the experiment
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Triglyceride Concentration | After each 24-hour dietary condition | Plasma triglyceride concentrations assessed at baseline and postprandially for 2 hours after a mixed meal test |
| Glucose Concentration | After each 24-hour dietary condition | Plasma glucose concentrations assessed at baseline and postprandially for 2 hours after a mixed meal test |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Insulin Concentration | After each 24-hour dietary condition | Plasma insulin concentrations assessed postprandially for 2 hours after a mixed meal test |
| Non-esterified Fatty Acid Concentration | After each 24-hour dietary condition | Plasma non-esterified fatty acid concentrations assessed at baseline and postprandially for 2 hours after a mixed meal test |
| Beta-hydroxybutyrate Concentration | After each 24-hour dietary condition | Plasma beta-hydroxybutyrate concentrations assessed at baseline and postprandially for 2 hours after a mixed meal test |
| Substrate Oxidation | After each 24-hour dietary condition | Lipid and carbohydrate oxidation assessed via indirect calorimetry at baseline and during 2-hour mixed meal test |
Countries
United Kingdom
Outcome results
None listed