Description and evaluation of an experimental model to examine changes in selection between high-protein, high-carbohydrate and high-fat foods in humans

Abstract

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. Design: Randomised counterbalanced (Latin square) design. Setting: The metabolic suite at the Rowett Research Institute's Human Nutrition Unit. Subjects: 16 normal-weight men (mean BMI 23.5). Interventions: Subjects were each studied 4 times in a 2-day protocol. On day 1 subjects received a ®xed 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 ( $ 60%), the remainder being equally split between the other two macronutrients. Results: Subjects were signi®cantly less hungry before lunch on the HP and M (33% protein) treatments (F 3Y44 7X35; P`0.001). At lunch, they ate more energy after the HF treatment than after any of the other treatment (F 1Y38 9X00; 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 (F 1Y42 6X90; P 0.012). Daily EIs were similar across treatments. Conclusion: This design appears sensitive meal-to-meal to changes in both nutrient and EIs. Sponsorship: This work was supported by the Scottish Of®ce, Agriculture, Environment and Fisheries Department.

Multifunctional roles of dietary proteins in the regulation of metabolism and food intake: Application to feeding infants

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The impact of the covert manipulation of macronutrient intake on energy intake and the variability in daily food intake in nonobese men

“…There has been considerable criticism regarding the relative importance of macronutrient-specific regulatory systems, since the energy density of foods may be a more critical factor than their macronutrient composition. 8 In addition, other factors, such as social and cultural cues, may dictate the initiation and termination of feeding. 9 The primary purpose of this study was to examine the effect of altering macronutrient composition on the regulation of daily food intake for a prolonged period (8 weeks).…”

Short-Term Effect of Eggs on Satiety in Overweight and Obese Subjects

“…To date, five breakfast studies using randomized cross-over designs have examined the impact of different macronutrients on subsequent food intake; four of these five examined the impact on satiety [5][6][7][8][9][10]. All five studies included averageweight subjects among whom the influence of satiety and macronutrient content on subsequent food intake may differ from that of overweight and obese subjects.…”