Rationale: Body weight is not well regulated in all individuals. In an obesogenic environment, where overeating is common, some individuals are more prone to weight gain and therefore overweight than others. Yet, the reasons behind this are unclear. "Resistant" individuals often have higher physical activity levels (PALs). It seems that - at higher levels of physical activity and therefore energy expenditure - satiety signals are more precisely regulated, making one better at matching energy intake with expenditure. In other words, active people may not overeat where sedentary people would. However, this does not explain the differences in weight gain observed when subjects all have to overeat (imposed overfeeding). It could be that active people are better able to cope metabolically with the extra calories because of already higher levels of carbohydrate and fat oxidation compared to their inactive counterparts. Objectives: 1/ To study the effects of overfeeding (normal diet composition) on substrate balance and oxidation and more specifically fat balance and oxidation; 2/ to study the effects of exercise and training on fat oxidation during overfeeding (normal diet composition). Study design: This controlled intervention study will follow a cross-over design. Each subject will spend 5 nights and 4 days in a respiration chamber on two occasions, separated by a 10-week training period.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
5
Maastricht University
Maastricht, Limburg, Netherlands
Change in 24-hour fat balance with overfeeding after training
Day3 24-hour fat balance (calculated as the difference between metabolisable fat intake and fat oxidation measured by indirect calorimetry in respiration chamber) after training compared to baseline (=before training)
Time frame: Baseline and 3 months
Change in 24-hour fat balance with overfeeding and exercise after training
Day4 24-hour fat balance (calculated as the difference between metabolisable fat intake and fat oxidation measured by indirect calorimetry in respiration chamber) after training compared to baseline (=before training)
Time frame: Baseline and 3 months
Change in 24-hour fat oxidation with overfeeding and exercise in inactive men
Fat oxidation measured by indirect calorimetry in respiration chamber on day 4 compared to day 3 at baseline
Time frame: Day 3 and day 4 (baseline stay in respiration chamber)
Change in 24-hour carbohydrate oxidation with overfeeding and exercise in inactive men
Carbohydrate oxidation measured by indirect calorimetry in respiration chamber on day 4 compared to day 3 at baseline
Time frame: Day 3 and day 4 (baseline stay in respiration chamber)
Change in 24-hour fat balance with overfeeding and exercise in inactive men
Fat balance (calculated as the difference between metabolisable fat intake and fat oxidation) on day 4 compared to day 3 at baseline
Time frame: Day 3 and day 4 (baseline stay in respiration chamber)
Change in 24-hour fat oxidation with overfeeding and exercise in active men
Fat oxidation measured by indirect calorimetry in respiration chamber on day 4 compared to day 3 after the training period
Time frame: Day 3 and day 4 (stay in respiration chamber at 3 months)
Change in 24-hour carbohydrate oxidation with overfeeding and exercise in active men
Carbohydrate oxidation measured by indirect calorimetry in respiration chamber on day 4 compared to day 3 after the training period
Time frame: Day 3 and day 4 (stay in respiration chamber at 3 months)
Change in 24-hour fat balance with overfeeding and exercise in active men
Fat balance (calculated as the difference between metabolisable fat intake and fat oxidation) on day 4 compared to day 3 after the training period
Time frame: Day 3 and day 4 (stay in respiration chamber at 3 months)
Change in 24-hour carbohydrate oxidation with overfeeding after training
Day3 24-hour carbohydrate oxidation measured by indirect calorimetry in respiration chamber after training compared to baseline (=before training)
Time frame: Baseline and 3 months
Change in 24-hour carbohydrate oxidation with overfeeding and exercise after training
Day4 24-hour carbohydrate oxidation measured by indirect calorimetry in respiration chamber after training compared to baseline (=before training)
Time frame: Baseline and 3 months
Change in fat oxidation after training assessed in energy balance
Time frame: Baseline and 3 months
Change in carbohydrate oxidation after training assessed in energy balance
Time frame: Baseline and 3 months
Energy expenditure with overfeeding in inactive men
Energy expenditure measured by indirect calorimetry during a 4-day stay in respiration chamber, with overfeeding on days 2 to 4.
Time frame: 4 days at baseline
Energy expenditure with overfeeding in active men
Energy expenditure measured by indirect calorimetry during a 4-day stay in respiration chamber, with overfeeding on days 2 to 4, after a 10-week fitness training.
Time frame: 4 days at 3 months
Insulin sensitivity
Based on glucose and insulin plasma concentrations from oral glucose tolerance test, where blood is collected in fasted state at t=0, 30, 60, 90 and 120min after a glucose drink is ingested)
Time frame: Baseline, 2 weeks (pre-training), 3 months (post-training)
adipocyte size
Fat biopsy taken these time points
Time frame: Baseline, 2 weeks (pre-training), 3 months (post-training)
Genes involved in lipid metabolism
Using fat biopsies: analysis of genes involved in the lipolytic pathway \[ATGL (PNPLA2), HSL (S660/565/563), CGI-58, G0S2, PLIN1, AQP7, GK\], in insulin signaling/glucose metabolism \[GLUT4, IRS1/IRS2, AKT, pAKT (S473), pIRS1 (S1101)\], in fatty acid metabolism \[CD36, FABP4 (aP2), FASN, CPT1a/1b, CPT2, ACADL/ACADVL/ACADS/ACADM, ACOX1, OXPHOS (complex I-V), PPAR(α/βδ/γ), PGC1a, PGC1b, SIRT1, AMPK (pAMPK)\], and in DAG/ceramide metabolism \[DGAT 1/2, GPAT1/GPAM, PLC, SPTLC1 and SPTLC2, CERK, ASAH1 and ASAH2
Time frame: Baseline, 2 weeks (pre-training), 3 months (post-training)
Change in body composition
Measured using body weight, underwater weighing and deuterium dilution, before and after the fitness training
Time frame: Baseline and 3 months
Change in cardiorespiratory fitness
Cardiorespiratory fitness estimated as the maximal oxygen uptake (VO2max) assessed using an incremental test on a bicycle ergometer
Time frame: Baseline, after 6-7 weeks of training and 3 months
Change in energy expenditure in free-living conditions
Energy expenditure measured over 14 days using doubly-labeled water and two accelerometers (TracmorD and Actigraph GT3X)
Time frame: Baseline and 3 months
Validity of Actigraph GT3X accelerometer
The Actigraph GT3X accelerometer is worn by each subject twice for 14 days and will be validated against the doubly labeled water technique and compared to the tracmorD accelerometer
Time frame: Two 14-day periods (baseline and 3 months)
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