Protein Dose-repsonse Effect on GLP-1, PYY and Appetite in Male Subjects
Condition: Obesity
Study type: Interventional

Summary: 
      Dietary protein appears to be the most satiating and thermogenic macronutrient. However, how
      protein exerts its effect on appetite is not fully known. The effect have been suggested to
      be related to a higher oxidation rate of protein compared to carbohydrate and fat, and also
      to a greater thermogenic effect causing greater increase in core temperature. The involvement
      of peripheral appetite-regulating hormones has only been sparingly investigated.

      The objective is to investigate the satiating effects of meals with varying content of
      meat-based protein and whether a dose-response effect can be found on appetite-regulating
      hormones and appetite ratings.

      Design: 25 men will participate in the 3-way, randomized, double-blind, crossover study. The
      test meals is isocaloric with 30E% fat and increasing protein content at the expense of
      carbohydrate. Test meals are: normal protein content (NP, 14E% protein), medium-high protein
      content (MHP, 25E%), and high protein content(HP, 50E%). Four-hour subjective appetite
      ratings and blood samples will be assessed every half-hour. Subsequently, the subjects will
      served an ad libitum lunch.
    

Detailed description: 
      Dietary protein appears to be the most satiating and thermogenic macronutrient (7-11).
      However, how protein exerts its effect on appetite is not fully known. The effect have been
      suggested to be related to a higher oxidation rate of protein compared to carbohydrate and
      fat (12), and also to a greater thermogenic effect causing greater increase in core
      temperature (13). The involvement of peripheral appetite-regulating hormones has only been
      sparingly investigated (14). These studies have only included two preloads of different
      concentrations of protein. This is not an optimal design for investigating the protein
      dose-dependent effect as the threshold can have been reached in between the two
      concentrations. The effect of protein has mainly been investigated on glucagon-like peptide-1
      (GLP-1), ghrelin, cholecystokinin (CCK), and generally after intake of protein below 35% of
      the energy content (35E%) (5;15-18). The relationship between these appetite-regulating
      hormones and appetite is still elusive due to contradicting results. Only one study has
      investigated the effect of protein preloads above 50E%. Bowen et al. (19) found that the high
      protein preloads could decrease the concentration of CCK and the rate of gastric emptying,
      which have been shown to enhance the satiating effect of food (20-22). Thus there is a need
      to examine the effect of protein on appetite-regulating hormones in a dose-response manner in
      order to detect whether there is an interaction between them and if they can be related to
      changes in subjective sensations of appetite and EI (14). This should be examined by
      comparing more than two isocaloric meals in which the protein content and one other
      macronutrient should vary whereas the third macronutrient should be kept fixed.

      Thus, the objective of this study is to investigate the mechanisms responsible for the
      satiating effects of protein in three isocaloric test meals with a protein content of 14, 25
      or 50 E% protein. A possible dose-response effect of protein is investigated on a number of
      appetite-regulating hormones/peptides, together with changes in ad libitum energy intake.

      Design: 25 men will participate in the 3-way, randomized, double-blind, crossover study. The
      test meals is isocaloric with 30E% fat and increasing protein content at the expense of
      carbohydrate. Test meals are: normal protein content (NP, 14E% protein), medium-high protein
      content (MHP, 25E%), and high protein content(HP, 50E%). Four-hour subjective appetite
      ratings and blood samples will be assessed every half-hour. Subsequently, the subjects will
      served an ad libitum lunch.
    

Intervention name(s): Dose-reponse effect of protein on appetite and appetite-regulating hormones
Intervention type(s): Other
Intervention description(s): 3-arm meal study for investigation of the mechanisms responsible for the satiating effects of protein in three isocaloric test meals with a protein content of 14, 25 or 50 E% protein. A possible 4-h dose-response effect of protein was investigated on a number of appetite-regulating hormones/peptides, together with changes in subjective appetite sensations and sensory desires were evaluated and ad libitum energy intake.
Intervention MeSH terms: Hormones
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Prevention
Keywords: Protein; Appetite; Satiety; Energi intake; Appetite regulating hormones; Dose-response