Effect of Acute Exercise on Food Intake and Energy Expenditure Following a Gastric Bypass

This pilot study will use a crossover design to explore the effects of acute exercise following bariatric surgery on food intake, energy expenditure, appetite, food reward, appetite hormones, and inflammatory response. Participants will take part in a moderate-intensity exercise session and control condition of 50 minutes. The energy balance will be assessed for 3 days following the condition by giving the participants all the food they can consume for 3 days and having them wear an accelerometer. The investigators hypothesize that post-gastric bypass participants with higher weight regain will have a higher compensation in response to exercise, thus an increase in food intake and/or a decrease in total energy expenditure after exercise compared to participants with less weight regain; also post-gastric bypass participants with a higher weight regain will have a lower inflammatory response to exercise compared to the group with less weight regain.

Objectives. 1. Explore the feasibility of a multicenter study in post-GB patients; 2. Explore the effects of acute exercise on food intake and energy expenditure post-GB; 3. Explore the effects of acute exercise on the hormonal and inflammatory response post-exercise. This pilot study will employ crossover design. The Behavioural and Metabolic Research Unit (BMRU) at the School of Human Kinetics of the University of Ottawa will coordinate and standardize the project between the sites. The participants will need to go 5 times to one of the 3 evaluation sites (University of Ottawa: BMRU, Montreal: University of Montreal, School of kinesiology and physical activity or University of Sherbrooke: Research Aging Center of CIUSSS - CHUS). Considering this is a pilot project, no sample size calculations were conducted. Based on existing studies, 30 participants should be sufficient to achieve the preliminary objectives of this study. The participants will be asked to present themselves at the evaluation centre on 5 occasions (1 preliminary, 2 experimental, 2 to return leftovers and accelerometers). During the visits 1, 2 and 4 (1 preliminary and 2 experimental (exercise and control)), the participants will arrive at 7:00 a.m. at the laboratory after 12 hours nocturnal fast. At 9:00 a.m., they will consume a standardized personalized breakfast. Participants will choose themselves the breakfast they want from a validated menu. They will be informed that they can consume the desired quantity of each product; the quantities will be measured to assure the breakfast for the other visits is identical. During the 1st session, depressive symptoms, the body composition (DEXA), resting metabolic rate and anthropometrics (weight, height, waist circumference) will be measured before breakfast. Afterwards, their socio-demographic information, motivation to eat and binge eating behaviors will be assessed. At 10:30 a.m., participants will perform submaximal exercise for 30 minutes to familiarize themselves with the treadmill, determine the speed and incline of the treadmill to achieve 55% estimated HRR and obtain an estimation of EE during the experimental condition. Subsequently to the first visit, the participants will wear an accelerometer for 7 days and bring it back for the 2nd visit. The day before the 2nd visit, the participants will fill out a food intake journal of the last 24 hours in order to consume the exact same foods (items, quantities and timeframe) the day before the 3rd session. At least one week after the 1st session, participants will present themselves to the evaluation site for the 2nd session to take part in one of the 2 experimental conditions (control and exercise), which will be randomly assigned and spaced a minimum of 15 days and a maximum of 2 months, yet to be performed the same day of the week. Women will only be tested between day 1 and 8 of their follicular phase. During the experimental conditions, participants will perform exercise on a treadmill (50 minutes at 55% of estimated HRR) (exercise condition) or the controlled condition (inactive period of calm and stress-free reading) at 10:30 a.m. Sixty minutes following exercise or the inactive period, an ad libitum buffet will be served to assess caloric and macro-nutritional intake. Appetite sensations will be assessed in the morning during fasting, before/after exercise, before/after ad libitum buffet as well as 1 and 2 hours after eating. Food rewards will be measured before and 1 hour after the meal. Blood samples will be collected 5 times by a nurse after a catheter has been installed, representing a total of 108 ml of blood collected (morning during fasting, before/after exercise or control condition, 30 minutes after exercise or control condition and before the buffet) to analyze appetite-related hormones (ghrelin, peptide YY (PYY) and glucagon-like peptide-1 (GLP-1)) and inflammatory parameters (IL-6, IL-10, IL-1ra, IL-8, TNF-α, sTNFR, MIP-1β, MCP-1). Finally, participants will wear an accelerometer (Actigraph® GT3X+) for 3 days following the sessions to determine their total EE outside of the laboratory. They will also leave with 3 days' worth of meals of their choice and will need to bring back any leftovers in order to calculate their caloric intake. In the exercise condition, a 50-minute effort at 55% of the estimated HRR will be performed on the treadmill following a 3-minute warm-up at 2.5 km/h and will be followed by a 2-minute active recovery period at 2.5 km/h then sitting for 3 minutes. The estimated maximum heart rate will be calculated from the most accurate prediction equation for a population with obesity: 208 - 0.7 × age. The heart rate will be monitored with a heart rate monitor throughout the exercise and recovery to ensure that the intensity of the exercise is maintained. The energy intake and macronutrients from the ad libitum will be measured with the validated technique of the food menu. A total of 62 items will be on the menu to ensure that sufficient hot meals, snacks, fruits, vegetables and beverages are available to the participants. Briefly, participants will be invited to choose from this validated menu, their breakfast, the meals they would like to have for lunch and after lunch the meals they would like to eat for the next 3 days (from midnight to midnight). The research assistant/student will instruct them to consume as much of these products as they want. All selected foods will be prepared and measured according to the guidelines described above (34). The food and beverages selected for the 3 days will be packed in plastic containers or bottles, which will be placed in a portable cooler for the participants to take with them. They must return all leftovers in their original containers. The selected and prepared foods will be weighted to the nearest gram using an electronic food scale before being consumed or placed in coolers. The macronutrient composition of foods and beverages consumed will be determined and analyzed in Ottawa using Food Processor SQL software (version 9.6.2; ESHA Research). Appetite and satiety will be measured using a computer-based visual analogue scale (VAS) (0-100mm). The desire to eat, hunger, satiety and potential food consumption will be assessed. The level of satiety will be evaluated using the "satiety quotient" method adapted from Green et al, which quantify variations in subjective appetite measurements (mm) for each 100kcal of food consumed. The Leeds Food Preference Questionnaire (LFPQ) will be used to assess food reward, i.e. explicit food pleasure and implicit and explicit food motivation. Blood samples taken with a catheter placed in the anterior ulnar vein of the dominant arm will be collected by a qualified nurse. The blood plasma samples collected for hormone analysis (ghrelin, PYY, GLP-1) will be collected in EDTA tubes. Immediately after blood sampling, a precise protocol will be used for each targeted hormone to preserve their integrity.