Exercise increases energy expenditure and impacts appetite and energy intake. Some appetite-related hormones such as oxyntomodulin suppress appetite whilst other hormones such as ghrelin stimulate appetite. This study will investigate whether acute continuous walking/jogging influences these hormone concentrations, and whether exercise-induced changes in the hormones correlate with perceptions of appetite, nutritional intake and brain activity in individuals varying in weight status.
Single bouts of exercise transiently suppress appetite and the orexigenic gut hormone acylated ghrelin and increase anorexigenic gut hormone concentrations including peptide YY (PYY) and glucagon-like peptide-1 (GLP-1). These changes occur without stimulating compensatory increases in appetite and energy intake on the day of exercise resulting in a short-term energy deficit. Oxyntomodulin is another gut-derived hormone that suppresses appetite and increases energy expenditure but the influence of acute exercise on oxyntomodulin concentrations in individuals varying in adiposity status has not been investigated. This study will investigate whether acute continuous walking/jogging impacts circulating oxyntomodulin concentrations in individuals who are lean or living with overweight or obesity. The influence of exercise and adiposity on other hormonal, subjective, sensory and neural correlates of appetite will also be explored. This study is a cross-over design consisting of four visits: a pre-visit, two main trial visits (exercise and control) and a magnetic resonance imaging (MRI) visit. Participants will undertake a preliminary measures visit (pre-visit) to confirm eligibility, complete questionnaires assessing their health, habitual physical activity and eating behaviours, undergo standard anthropometric measurements (height, weight, and hip/waist circumference) and treadmill exercise tests to determine their peak oxygen uptake. Main trials will be separated by at least seven days for male participants, whereas female participants will complete the two main trials in the follicular phase (the first seven days) of the menstrual cycle. Participants will arrive at the laboratory after fasting overnight for at least 10 hours (plain water is permitted). Participants will then complete assessments of height, weight and either bioelectrical impedance analysis (main trial 1) or air displacement plethysmography (BOD POD®) (main trial 2). A venous cannula will be inserted for the collection of venous blood samples at 30-minute intervals (0 hours \[08:30\], 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours and 4 hours). Subjective appetite ratings will be measured at 30-minute intervals (0 hours \[08:30\], 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours and 4.5 hours). Participants will complete the Burghart ODOFIN Sniffin' Sticks smell test and the Burghart ODOFIN taste strips test at three time points during the trials (0 hours \[08:30\], 1.5 hours and 4 hours). Participants will rest for the duration of the trials except for performing 1 hour of treadmill exercise (walking/jogging) at 60% of their peak oxygen uptake (calculated from the pre-visit) between 0.5 to 1.5 hours (09:00-10:00) in the exercise trial. Expired air samples will be collected during exercise and for 30 minutes during the rest trial to calculate net energy expenditure and substrate oxidation. At 2.5 hours (11:00), an ad libitum lunch consisting of a homogeneous meal containing pasta, tomato sauce, and olive oil (72% carbohydrate, 12% protein, 16% fat, 6.5 kJ per gram of food) will be provided for 30 minutes (until 3 hours). The MRI visit will take place after an overnight fast of at least 10 hours and will involve a 45 minute scanning protocol. Structural MRI and functional MRI (fMRI) scans will be performed on a GE 3.0 T Discovery MR750w scanner using a 32 channel head coil. Two fMRI scans will be performed (1) during the presentation of food and non-food cues and (2) for an equivalent duration whilst participants are not looking at food and non-food cues.
Exercise, which will involve 60 minutes of brisk walking, or jogging, at 60% of peak oxygen uptake. Participants will be asked to wear a face mask, which will measure their oxygen consumption during the exercise session.
Loughborough University
Loughborough, United Kingdom
Concentration of Oxyntomodulin
Plasma blood samples
Time frame: Blood samples to measure oxyntomodulin are collected at 30-minute intervals (0 hours [08:30], 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours and 4 hours) in each trial.
Concentration of Acylated Ghrelin
Acylated Ghrelin. Blood plasma sample.
Time frame: Blood samples to measure acylated ghrelin are collected at 30-minute intervals (0 hours [08:30], 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours and 4 hours) in each trial.
Concentration of Leptin
Blood plasma sample.
Time frame: Blood samples to measure leptin are collected at 0 hours [08:30] in each trial.
Concentration of Glucagon-like peptide 1
Glucagon-like peptide 1 (GLP-1). Blood plasma sample.
Time frame: Blood samples to measure GLP-1 are collected at 30-minute intervals (0 hours [08:30], 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours and 4 hours) in each trial.
Concentration of Peptide YY
Peptide YY (PYY) plasma blood sample
Time frame: Blood samples to measure PYY are collected at 30-minute intervals (0 hours [08:30], 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours and 4 hours) in each trial.
Concentration of Glucose
Blood plasma sample
Time frame: Blood samples to measure glucose are collected at 30-minute intervals (0 hours [08:30], 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours and 4 hours) in each trial.
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Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
40
Visual analogue score (VAS) for subjective appetite
Participants subjective appetite sensations are assessed using 100mm visual analogue scales to measure four appetite constructs: 'hunger', 'fullness', 'satiety' and 'prospective food consumption'.
Time frame: VAS is measured at 30-minute intervals (0 hours [08:30], 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours and 4.5 hours) in each trial.
Energy intake
(kcal). A large bowl containing an amount of pasta in excess of expected consumption is presented to participants for 30 minutes. They are instructed to self-serve and to stop eating when they reach volitional satiation. The remaining food is weighed and subtracted from the known quantity initially presented to calculate ad libitum energy intake.
Time frame: The ad libitum pasta meal is provided at 2.5 hours (11:00)
Gustatory perceptions
The Burghart ODOFIN taste strips test is used to evaluate participant's ability to detect different taste sensations. It assesses the sensitivity of a person's taste buds to various taste qualities, including sweet, salty, sour, bitter, and umami (savoury) and some taste strips may have no taste at all (neutral). The paper strips are placed in the middle of the anterior tongue and the participant will be asked to identify the taste. Participants are asked to take a sip of water between each paper strip.
Time frame: The taste tests will take place at three time points during the trials: 0 hours [08:30], 1.5 hours and 4 hours.
Olfactory perceptions
The Burghart ODOFIN Sniffin' Sticks smell test is used to evaluate the person's ability to detect, identify, and differentiate various odours. The test involves presenting a series of different odours in the form of sniff pens. The participant will be asked to sniff each pen and then identify each odour from a card which is presented to them.
Time frame: The smell tests will take place at three time points during the trials: 0 hours [08:30], 1.5 hours and 4 hours.
Task-based fMRI
Brain responses to visual food cues assessed during the presentation of food and non-food images
Time frame: 45-minute scan at baseline
Resting state fMRI
Functional activity of the brain assessed at rest.
Time frame: 45-minute scan at baseline