Fasted Evening Exercise: Performance and Compensatory Eating

Study Overview
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Brief Summary
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This study will compare the appetite, energy intake, and exercise performance responses to a bout of exercise completed in the evening after an extended period of fasting with a similar bout of exercise completed in the evening and the morning, after consuming a carbohydrate-containing meal.

Detailed Description
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Regular exercise is known to be a successful strategy for improving several facets of health and maintaining body weight. However, many people are not engaging in enough exercise, and some may not be achieving maximum benefits from the exercise that they already do. Performing exercise in the overnight fasted state has been shown to reduce energy intake over the course of a single day, without any compensatory reductions in free-living energy expenditure. Despite these promising findings, it is likely that not every member of the population is logistically able to perform exercise in the morning due to various work, family and social commitments, and exercise in the evening may be a logical alternative for these individuals. Whether the beneficial effects of overnight fasted exercise can be observed at an alternative time of the day (i.e. the evening) is unknown. Therefore, the investigators are interested in examining the compensatory appetite and energy intake responses following a bout of evening exercise performed after an extended (7 hour) period of fasting. Exercise performance will also be assessed as a marker of voluntary energy expenditure, which if reduced, has the potential to compensate for the reduced energy balance induced by fasted exercise.

Official Title
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Effects of Extended Fasting Prior to Evening Exercise on Appetite, Energy Intake and Performance.

Conditions
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Obesity

Intervention / Treatment
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* Behavioral: Fasted Evening Exercise
* Behavioral: Fed Evening Exercise
* Behavioral: Fed Morning Exercise


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Non-smokers. Have maintained a stable weight for 6 months (self-reported). No history of gastric, digestive, cardiovascular or renal disease (self-reported). Female specific: must be using a monophasic, low dose combined OCP (containing less than 50μg oestradiol and a synthetic progestin) OR females with regular menstrual cycles (self-reported). Exclusion Criteria: Have an unusual eating pattern (i.e., extended fasting periods >8h other than overnight - self-reported). Severe food allergies, dislike or intolerance of study foods or drinks. Currently undergoing a lifestyle intervention (structured diet or exercise) Diagnosis of a condition or currently undergoing treatment therapy known to affect glucose or lipid metabolism (e.g., type-2 diabetes, taking statins), or contraindications to exercise. Use of medication or supplements that may affect hormone concentrations. Excessive alcohol consumption (>14 units/week). Intensive training schedule (>10 hours/week). Having received a positive COVID-19 test in the 6-month period prior to participation. Female specific: currently pregnant or breastfeeding, the use of any hormonal contraception, and the self-reporting of short (<24 d), long (>35 d), or irregular menstrual cycles.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 40 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: The study design is a randomised, controlled, crossover design in which participants undertake three exercise conditions in a randomised order with at least a seven day period in between trials.
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Fasted Evening Exercise<br>Exercise will take place in the evening, following a 7 hour period of fasting. | Behavioral: Fasted Evening Exercise<br>* A 45 minute exercise session will take place on a stationary cycle ergometer at 18:30, after a 7-hour period of fasting. This will consist of 30 minutes of steady state cycling at 60% of VO2max, followed by an exercise test during which participants will complete as much work as they can within 15 minutes.<br>|
| Active Comparator: Fed Evening Exercise<br>Exercise will take place in the evening, after having consumed a carbohydrate-containing meal 2 hours prior. | Behavioral: Fed Evening Exercise<br>* A 45 minute exercise session will take place on a stationary cycle ergometer at 18:30, after having consumed a carbohydrate-containing meal (20% estimated energy requirements) 2 hours prior. This will consist of 30 minutes of steady state cycling at 60% of VO2max, followed by an exercise test during which participants will complete as much work as they can within 15 minutes.<br>|
| Active Comparator: Fed Morning Exercise<br>Exercise will take place in the morning, after having consumed a carbohydrate-containing meal 2 hours prior. | Behavioral: Fed Morning Exercise<br>* A 45 minute exercise session will take place on a stationary cycle ergometer at 10:30, after having consumed a carbohydrate-containing meal (20% estimated energy requirements) 2 hours prior. This will consist of 30 minutes of steady state cycling at 60% of VO2max, followed by an exercise test during which participants will complete as much work as they can within 15 minutes.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Voluntary energy intake (Kilocalories) at a laboratory-based test meal | A laboratory-based meal consisting of pasta, tomato sauce and olive oil will be provided to participants in excess of expected consumption. Participants will be permitted 20 minutes to eat as much or as little as they desire, until 'comfortably full and satisfied'. | 15 minutes following the end of the exercise session. | 
| Exercise Performance (Voluntary Energy Expenditure) | Maximum energy expenditure (Kilojoules) that can be completed within 15 minutes on a stationary bicycle ergometer. The participant will be able to alter their power output by selecting up or down on the ergometer control unit as they please. | Within the 15-minute performance test component of the exercise session. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Visual Analogue Scale for Subjective Ratings of Appetite | Time-course of subjective ratings of hunger between breakfast provision and one hour after consuming lunch, measured using an appetite visual analogue scale. The scale is divided into subscales of different appetite perceptions including: hunger, fullness, desire to eat and prospective food consumption. Each subscale is rated on a 100mm scale (i.e. from 0 - 100), with a rating of 100 fully supporting the perception and a rating of 0 fully opposing the perception. | Baseline, 2 hours, 3 hours, 3.5 hours, 5 hours, 7 hours, 8 hours, 10 hours, 11 hours, 12 hours, 14 hours, and 24 hours. | 
| Substrate Utilisation During Steady State Exercise. | Measurements of VO2 and VCO2 during a 30 minute steady state bout of cycling which precedes the 15-minute performance test. | Within the 30-minute steady-state component of the exercise session. | 
| Rating of Perceived Exertion (RPE). | RPE will be measured at 5-minute intervals throughout the 45-minute exercise period (30 min steady state; 15 min performance test) on a 6-20 RPE scale. The participant will point to the value that corresponds to their current perceived exertion (6 being no exertion at all; 20 being maximal exertion). | Within the 45-minute exercise session. | 
| Enjoyment of the Exercise Bout | A shortened version of The Physical Activity Enjoyment Scale (PACES) will be completed to gauge enjoyment of the exercise sessions. A scale from 1-7 will be used for eight feelings. The participant will circle the value that corresponds to which (6 being no exertion at all; 20 being maximal exertion). The scale is divided into bipolar subscales of different feelings including: enjoyment, liking, pleasure, fun, pleasantness, interest, engagement and task absorption . Each subscale is rated on a 1-7 bipolar scale (i.e. from 1 - 7), with a rating of 1 fully supporting the feeling on the left-hand side of the subscale, and a rating of 7 fully supporting the feeling on the right-hand side of the subscale. For three subscales, a positive feeling is placed at 7, and for four subscales, a negative feeling is placed at 7 (reverse scored). | Immediately following the end of the exercise session. | 
| Pre-exercise Subjective Feelings | A single questionnaire to assess pre-exercise subjective feelings will be measured using a visual analogue scale. The scale is divided into subscales of different feelings including: motivation, readiness, tiredness, nausea, and energetic. Each subscale is rated on a 100mm scale (i.e. from 0 - 100), with a rating of 100 fully supporting the perception and a rating of 0 fully opposing the perception. | Immediately before the exercise session. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Energy balance, Fasted exercise, Energy intake, Appetite, Exercise performance