Description and evaluation of an experimental model to examine changes in selection between high-protein, high-carbohydrate and high-fat foods in humans.
OBJECTIVE
To develop and test an experimental model designed to detect changes in selection between foods individually enriched in protein, carbohydrate and fat in human subjects.


METHODS
Randomised counterbalanced (Latin square) design.


METHODS
The metabolic suite at the Rowett Research Institute's Human Nutrition Unit.


METHODS
16 normal-weight men (mean BMI = 23.5).


METHODS
Subjects were each studied 4 times in a 2-day protocol. On day 1 subjects received a fixed maintenance diet; on day 2 they received a mandatory intake as breakfast (08.30) plus a drink at 10.30. This comprised 80% of resting energy requirements as high-protein (HP), high-carbohydrate (HC) or high-fat (HF) foods (60% of energy in each case) or an equal mixture (M) of macronutrients, 33% by energy. All mandatory treatments contained the same energy content and density. From 12.30 onwards, subjects had ad libitum access to a counter-balanced selection of three groups of familiar foods (10 HP, 10 HC and 10 HF; 30 foods in total). Most energy in each food was derived from one macronutrient (approximately 60%), the remainder being equally split between the other two macronutrients.


RESULTS
Subjects were significantly less hungry before lunch on the HP and M (33% protein) treatments (F3.44 = 7.35; P < 0.001). At lunch, they ate more energy after the HF treatment than after any of the other treatment (F1,38 = 9.00; P = 0.005). This was largely in the form of fat and protein, and to a lesser extent carbohydrate. Subsequent energy intake (EI) were lower on the HF treatment, largely through selection of less fat in the afternoon (F1.42 = 6.90; P=0.012). Daily EIs were similar across treatments.


CONCLUSIONS
This design appears sensitive meal-to-meal to changes in both nutrient and EIs.
Stubbs
R J
RJ
The Rowett Research Institute, Bucksburn, Aberdeen, UK.
O'Reilly
L M
LM
Johnstone
A M
AM
Harrison
C L
CL
Clark
H
H
Franklin
M F
MF
Reid
C A
CA
Mazlan
N
N
D000328:Adult; D004040:Dietary Carbohydrates / Q000008:administration & dosage* / Q000378:metabolism; D004041:Dietary Fats / Q000008:administration & dosage* / Q000378:metabolism; D004044:Dietary Proteins / Q000008:administration & dosage* / Q000378:metabolism; D004435:Eating / Q000502:physiology*; D002149:Energy Intake / Q000502:physiology; D005518:Food Preferences / Q000502:physiology*; D006801:Humans; D006815:Hunger / Q000502:physiology; D008297:Male; D008954:Models, Biological; D015233:Models, Statistical; D012527:Satiation / Q000502:physiology; D011795:Surveys and Questionnaires
D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins