Description and evaluation of an experimental model to examine changes in selection between high-protein, high-carbohydrate and high-fat foods in humans
Rj. Stubbs et al., Description and evaluation of an experimental model to examine changes in selection between high-protein, high-carbohydrate and high-fat foods in humans, EUR J CL N, 53(1), 1999, pp. 13-21
Objective: To develop and test an experimental model designed to detect cha
nges in selection between foods individually enriched in protein, carbohydr
ate and fat in human subjects.
Design: Randomised counterbalanced (Latin square) design.
Setting: The metabolic suite at the Rowett Research Institute's Human Nutri
tion Unit. Subjects: 16 normal-weight men (mean BMI = 23.5).
Interventions: Subjects were each studied 4 times in a 2-day protocol. On d
ay 1 subjects received a fixed maintenance diet; on day 2 they received a m
andatory 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 mixtur
e (M) of macronutrients, 33% by energy. All mandatory treatments contained
the same energy content and density. From 12.30 onwards, subjects had nd li
bitum access to a counter-balanced selection of three groups of familiar fo
ods ( 10 HP, 10 HC and 10 HP; 30 foods in total). Most energy in each food
was derived from one macronutrient (similar to 60%), the remainder being eq
ually split between the other two macronutrients.
Results: Subjects were significantly less hungry before lunch on the HP and
M (33% protein) treatments (F-3.44 = 7.35; P < 0.001). At lunch, they ate
more energy after the HF treatment than after any of the other treatment (F
-1,(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 l
ower on the HF treatment, largely through selection of less fat in the afte
rnoon (F-1,F-42 = 6.90; P = 0.012). Daily EIs were similar across treatment
s.
Conclusion: This design appears sensitive meal-to-meal to changes in both n
utrient and EIs.