Individual Variability of Appetite Responses to a Standardised Meal
Condition: Appetitive Behavior; Obesity; Genetic Predisposition to Disease
MeSH terms: Genetic Predisposition to Disease
Study type: Interventional

Summary: 
      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.
    

Detailed description: 
      Meal ingestion initiates a series of co-ordinated subjective and hormonal appetite responses.
      However, it is not known whether interindividual variability in appetite exists in response
      to a standardised meal. A recent approach proposed to quantify individual differences in the
      intervention response involves quantifying the participant-by-response interaction from
      replicated intervention and comparator arms. Using this approach (a replicated crossover
      study), the current study will (1) investigate whether the perceived appetite and
      appetite-related hormone responses to a standardised meal are reproducible on repeated
      occasions; (2) examine whether there is true individual variability in appetite responses to
      a standardised meal; and (3) determine whether the fat mass and obesity associated gene (FTO)
      moderates the magnitude of appetite responses to a standardised meal.

      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). Participants will complete
      four main experimental conditions each separated by an interval of at least three days: two
      fasted control and two standardised meal conditions. Participants will arrive at the
      laboratory at 09:00 after a 13 h overnight fast and a cannula will be inserted into an
      antecubital vein for blood sampling. After 60 min rest, a fasting venous blood sample and
      rating of perceived appetite will be taken (0 h; 10:00). Participants will rest throughout
      all four conditions but will be provided with a standardised breakfast meal after the fasting
      measurements during the two meal conditions. Breakfast will be consumed within 15 min and
      consist of croissants, butter, chocolate spread, cereal biscuits and milkshake which will
      provide 5025 kJ energy (47% carbohydrate, 9% protein, 44% fat). Subsequent venous blood
      samples will be taken at 0.5 h (10:30) and 1 h (11:00), and appetite perceptions will be
      assessed at 1 h (11:00).

      Interindividual differences will be explored by correlating the two sets of response
      differences between meal and control conditions. Within-participant covariate-adjusted linear
      mixed models will be used to quantify participant-by-condition and FTO genotype-by-condition
      interactions.
    

Intervention name(s): Standardised meal
Intervention type(s): Behavioral
Intervention description(s): A standardised meal will be consumed at 10:00 which will provide 5025 kJ energy (47% carbohydrate, 9% protein, 44% fat).
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: Appetite; FTO; Ghrelin; Individual variability; Meal intake; Peptide YY