The aim of this study is to examine the interindividual variability of subjective and hormonal appetite responses to a standardised meal in healthy men and explore any moderating influence of the fat mass and obesity associated gene (FTO). Participants homozygous for the obesity risk A allele (AA) or low risk T allele (TT) of FTO rs9939609 will complete two fasted control and two standardised meal (5025 kJ energy, 47% carbohydrate, 9% protein, 44% fat) conditions in randomised sequences. Ratings of perceived appetite and venous blood samples will be taken before and after the interventions. Interindividual differences in appetite responses and the potential moderating influence of the FTO gene will be examined using bivariate correlations and linear mixed modelling.
Name: Standardised meal
Description: Control adjusted pre-to-post change in plasma acylated ghrelin concentration
Measure: Acylated ghrelin concentration Time: 1 hour (Plasma samples will be collected at 0 hour (pre) and 1 hour (post))Description: Control adjusted pre-to-post change in plasma total peptide YY concentration
Measure: Total peptide YY concentration Time: 1 hour (Plasma samples will be collected at 0 hour (pre) and 1 hour (post))Description: Control adjusted pre-to-post change in plasma insulin concentration
Measure: Insulin concentration Time: 0.5 hour (Plasma samples will be collected at 0 hour (pre) and 0.5 hour (post))Description: Control adjusted pre-to-post change in plasma glucose concentration
Measure: Glucose concentration Time: 0.5 hour (Plasma samples will be collected at 0 hour (pre) and 0.5 hour (post))Description: Control adjusted pre-to-post change in rating of perceived hunger. Perceived hunger will be measured using a 100 mm visual analogue scale anchored at 0, 'I am not hungry at all', and 100, 'I have never been more hungry'.
Measure: Rating of perceived hunger Time: 1 hour (Visual analogue scales will be completed at 0 hour (pre) and 1 hour (post))Description: Control adjusted pre-to-post change in rating of perceived satisfaction. Perceived satisfaction will be measured using a 100 mm visual analogue scale anchored at 0, 'I am completely empty', and 100, 'I cannot eat another bite'.
Measure: Rating of perceived satisfaction Time: 1 hour (Visual analogue scales will be completed at 0 hour (pre) and 1 hour (post))Description: Control adjusted pre-to-post change in rating of perceived fullness. Perceived fullness will be measured using a 100 mm visual analogue scale anchored at 0, 'Not full at all', and 100, 'Totally full'.
Measure: Rating of perceived fullness Time: 1 hour (Visual analogue scales will be completed at 0 hour (pre) and 1 hour (post))Description: Control adjusted pre-to-post change in rating of perceived prospective food consumption. Perceived prospective food consumption will be measured using a 100 mm visual analogue scale anchored at 0, 'Nothing at all', and 100, 'A lot'. consumption
Measure: Rating of perceived prospective food consumption Time: 1 hour (Visual analogue scales will be completed at 0 hour (pre) and 1 hour (post))Allocation: Randomized
Crossover Assignment
There is one SNP
Participants homozygous for the obesity risk A allele (AA) or low risk T allele (TT) of FTO rs9939609 will complete two fasted control and two standardised meal (5025 kJ energy, 47% carbohydrate, 9% protein, 44% fat) conditions in randomised sequences.
Inclusion Criteria: - Homozygous minor allele (AA) or major allele (TT) FTO rs9939609 genotype; - Non-smoker; - Weight stable for the previous 3 months.
Exclusion Criteria: - Heterozygous FTO rs9939609 genotype (i.e., AT); - Any medical conditions (e.g., diabetes, coagulation or bleeding disorders); - Taking any medication that might influence appetite, fat metabolism or blood glucose; - Dieting or restrained eating behaviours; - Any food allergies.
A total of 18 healthy men will be recruited according to their FTO rs9939609 genotype: 9 homozygous minor allele (AA) and 9 homozygous major allele (TT).