Protein Dose-repsonse Effect on GLP-1, PYY and Appetite in Male Subjects

University of Copenhagen

Status: Completed

Conditions: Obesity

Treatments: Other: Dose-reponse effect of protein on appetite and appetite-regulating hormones

Study type: Interventional

Funder types: Other

Identifiers

NCT01561235

B243

Details and patient eligibility

About

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.

Full 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.

Enrollment: 25 patients

Sex: Male

Ages: 18 to 50 years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

• Healthy,
• BMI: 18.5-40 kg/m2,
• Weight stable (within +/- 3 kg) two months prior to study inclusion,
• Non-smoking,
• Nonathletic,

Exclusion criteria

• BMI > 40 kg/m2,
• Change in smoking status,
• Daily or frequent use of medication,
• Suffering from metabolic diseases,
• Suffering from psychiatric diseases,
• Suffering from any other clinical condition, which would make the subject unfit to participate in the study,
• Blood pressure was above 150/90 mmHg,
• Hemoglobin < 8 mmol/l.

Trial design

Primary purpose: Prevention

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Quadruple Blind

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25 participants in 3 patient groups

Normal Protein

Active Comparator group

Description:

Energy content 3 or 4 MJ/meal, depending on the subject's individual daily energy requirements). Macronutrient content: Protein: 14 E%, Fat: 30 E% and carbohydrate: 56E%. The fibre content was similar in all three test meals. The test meals were served as pork/rice/mushroom pâtés, flavoured with thyme in order to blind differences in taste.

Treatment:

Other: Dose-reponse effect of protein on appetite and appetite-regulating hormones

Medium-high protein

Experimental group

Description:

Energy content 3 or 4 MJ/meal, depending on the subject's individual daily energy requirements). Macronutrient content: Protein: 25E%, Fat: 30 E% and carbohydrate: 45E%. The fibre content was similar in all three test meals. The test meals were served as pork/rice/mushroom pâtés, flavoured with thyme in order to blind differences in taste.

Treatment:

Other: Dose-reponse effect of protein on appetite and appetite-regulating hormones

High Protein

Experimental group

Description:

Energy content 3 or 4 MJ/meal, depending on the subject's individual daily energy requirements). Macronutrient content: Protein: 50 E%, Fat: 30 E% and carbohydrate: 20E%. The fibre content was similar in all three test meals. The test meals were served as pork/rice/mushroom pâtés, flavoured with thyme in order to blind differences in taste.

Treatment:

Other: Dose-reponse effect of protein on appetite and appetite-regulating hormones