A Phase 2 interventional study of 16 week exercise intervention in Obesity, Exercise and Weight Loss, sponsored by Arkansas Colleges of Health Education. Recruiting at 1 site in United States. Open to participants aged 18 Years to 59 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-03-23.
Sponsored by Arkansas Colleges of Health Education · Phase 2, Interventional, and Treatment
Although many medications exist for both heart disease and obesity, cost, lack of access for all people, side effects and the desire for a more natural solution have left many people seeking lifestyle treatments such as exercise. Scientists know that exercise is highly beneficial for heart health. When exercise also produces weight loss, these benefits are much improved. Although using exercise to treat or prevent heart disease / obesity is recommended, not all people respond well. Some see significant weight loss and health improvements while others see little changes. For these reasons, new strategies surrounding the use and design of an exercise program are needed. One such strategy could be performing aerobic exercise before breakfast (fasted exercise). When exercising fasted, food/energy stores are low, and one relies on stored body fat for energy. This may help heart health and weight loss. This has never been tested in a program long enough to see such changes. This study will, for the first time, assess the effects of a 16-week aerobic exercise program performed fasted compared to after eating. Outcomes will include blood fats, blood pressure, fat-burning abilities and weight loss.
Starting an exercise program can also make people to eat more. This limits the success of exercise. The study will also evaluate ways fasted exercise could change eating, as it possible that fasted exercise could also cause people to eat more, which would limit weight loss and health improvements.
This study will be the first to evaluate a long-term (16-week) aerobic exercise intervention performed in the fasted state (compared to fed state) at a guidelines-based dose. Primary outcomes for Aim 1 will include changes in fat \& fat-free mass (DXA), energy compensation, blood pressure \& lipids, aerobic fitness, and substrate oxidation (respiratory quotient, RQ) at rest and during activity.
It is also important to understand sources of response variability to an exercise program. Individuals tend to compensate for the energy they expend during exercise, primarily by increasing energy intake (EI). Such compensatory eating behaviors likely stem from a series of evolutionarily conserved responses, ensuring energy is available for vital organ function and reproduction when faced with an energy deficit. This proposal will be the first to evaluate how fasted exercise training influences (Aim 2 outcomes): physiological hunger (hormonal responses to a standardized meal) and behavioral constructs shown to influence EI and weight status (food reinforcement and attentional bias towards food cues). The overall hypothesis is that fasted state exercise will result in greater energy compensation, attenuating weight loss compared to an identical dose of exercise performed in the post-prandial state. This study will further hypothesize an attenuated weight loss with fasted exercise training will negate beneficial cardiovascular adaptations stemming from improvements in oxidative metabolism commonly associated with fasted exercise. Adults (aged 18-59 years, BMI: 25-45 kg/m2) will be randomized to a 16-week supervised aerobic exercise intervention (progressing to a guidelines-based dose of 1600 kcal/wk). Exercise sessions will be performed between 0500h and 1100h, 4 days per week in either the fasted state (FAST, 8-12 hour fast) or post-prandially (FED, within 3 hours of eating at least 300 kcal).
6,296 studies on the registry are indexed under Obesity; 1,692 are open to participants now.
This study's planned enrollment of 40 is below the median of 78 across 4,878 interventional studies indexed under Obesity.
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Exclusion Criteria:
Complete all exercise sessions of intervention before breakfast- fasted at least 8 hours
Behavioral: 16 week exercise intervention
Complete all exercise sessions of intervention after breakfast- within 3 hours of eating at least 300 kcal
Behavioral: 16 week exercise intervention
Both groups will receive a 16-week supervised aerobic exercise program progressing to 1,600 kcal of EE per wk (4 sessions/week) at moderate intensity (40-50% heart rate reserve, HRR).
body composition
kg of fat free and fat mass via DXA
Time frame: Baseline (week 0) and post-intervention (week 25)
Total and acylated ghrelin
Total and acylated ghrelin (pg/mL in plasma) will be assessed in the fasted state and response to a test meal via blood sampling at 0 minutes (pre meal), 15, 30, 45, 60, 90, and 120 minutes post-meal.
Time frame: Baseline (week 0) and post-intervention (week 25)
GLP-1
Glucagon-like peptide 1 (GLP-1, Pmol/L in plasma) will be assessed in the fasted state and response to a test meal via blood sampling at 0 minutes (pre meal), 15, 30, 45, 60, 90, and 120 minutes post-meal.
Time frame: Baseline (week 0) and post-intervention (week 25)
PYY
Peptide YY (PYY, pmol/L plasma) will be assessed in the fasted state and response to a test meal via blood sampling at 0 minutes (pre meal), 15, 30, 45, 60, 90, and 120 minutes post-meal.
Time frame: Baseline (week 0) and post-intervention (week 25)
Leptin
Leptin (ng/mL in plasma) will be assessed in the fasted state and response to a test meal via blood sampling at 0 minutes (pre meal), 15, 30, 45, 60, 90, and 120 minutes post-meal.
Time frame: Baseline (week 0) and post-intervention (week 25)
Food reinforcement
amount of work one is willing to do for a snack food
Time frame: Baseline (week 0) and post-intervention (week 25)
Attentional bias for food cues
percentage of time fixated on food cues during a dot-probe task, assessed by eye tracking
Time frame: Baseline (week 0) and post-intervention (week 25)
Skeletal muscle efficiency
kcal expended per kg per watt during a graded cycle ergometer test
Time frame: Baseline (week 0) and post-intervention (week 25)
walking ecconomy
Gross energetic cost of movement (J/kg/m) will be assessed during a graded walking test with indirect calorimetry.
Time frame: Baseline (week 0) and post-intervention (week 25)
resting metabolic rate
Resting metabolic rate assessed via indirect calorimetry
Time frame: Baseline (week 0) and post-intervention (week 25)
muscle strength
Peak torque and work per repetition (Foot-Pounds) will be assessed during an isokinetic and isometric task
Time frame: Baseline (week 0) and post-intervention (week 25)
muscle power
Average power (watts) will be assessed during an isokinetic and isometric task
Time frame: Baseline (week 0) and post-intervention (week 25)
skeletal muscle mass
The D3Cr dilution technique will be used to determine kg of skeletal muscle mass
Time frame: Baseline (week 0) and post-intervention (week 25)
Plan to share: Undecided
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Arkansas Colleges of Health Education