Effect of reducing portion size at a compulsory meal on later energy intake, gut hormones, and appetite in overweight adults

Abstract

Objective: Larger portion sizes (PS) are associated with greater energy intake (EI), but little evidence exists on the appetitive effects of PS reduction. This study investigated the impact of reducing breakfast PS on subsequent EI, postprandial gastrointestinal hormone responses, and appetite ratings.

Methods: In a randomized crossover design (n = 33 adults; mean BMI 29 kg/m(2) ), a compulsory breakfast was based on 25% of gender-specific estimated daily energy requirements; PS was reduced by 20% and 40%. EI was measured at an ad libitum lunch (240 min) and snack (360 min) and by weighed diet diaries until bed. Blood was sampled until lunch in 20 participants. Appetite ratings were measured using visual analogue scales.

Results: EI at lunch (control: 2,930 ± 203; 20% reduction: 2,853 ± 198; 40% reduction: 2,911 ± 179 kJ) and over the whole day except breakfast (control: 7,374 ± 361; 20% reduction: 7,566 ± 468; 40% reduction: 7,413 ± 417 kJ) did not differ. Postprandial PYY, GLP-1, GIP, insulin, and fullness profiles were lower and hunger, desire to eat, and prospective consumption higher following 40% reduction compared to control. Appetite ratings profiles, but not hormone concentrations, were associated with subsequent EI.

Conclusions: Smaller portions at breakfast led to reductions in gastrointestinal hormone secretion but did not affect subsequent energy intake, suggesting small reductions in portion size may be a useful strategy to constrain EI.

Figure 1

Overview of the time points for meals and measurements taken during a study day (GIP: glucose-dependent insulinotropic peptide; GLP-1: glucagon-like peptide 1; MRC HNR: Medical Research Council Human Nutrition Research; PYY: peptide tyrosine tyrosine; VAS: visual analogue scales).

Figure 2

Mean (± SEM) energy intake at A) lunch were not different between conditions (control vs. 20% reduction, β=-76.6, p=0.429; 20% reduction vs. 40% reduction, β=58.2, p=0.547; control vs. 40% reduction, β=-18.3, p=0.850); and B) over the whole day except breakfast (control vs. 20% reduction, β=192.3, p=0.555; 20% reduction vs. 40% reduction, β=-152.8, p=0.639; control vs. 40% reduction, β=39.5, p=0.904).

Figure 3

Postprandial response (mean ± SEM) of A) plasma PYY_3-36, B) plasma total GLP-1, and C) plasma total GIP, according to condition. ‘a’ indicates the mean of the condition is significantly different to the mean of the control condition at that time point. ‘b’ indicates the mean is significantly different to the mean of the 20% reduction condition at that time point (mixed effects models): p<0.05. Addition of * to the letter indicates p<0.01 and ** indicates p<0.001.

Figure 4

Postprandial response of A) plasma glucose (mean ± SEM), and B) plasma insulin (geometric mean ± 95% confidence intervals), according to condition. ‘a’ indicates the mean of the condition is significantly different to the mean of the control condition at that time point. ‘b’ indicates the mean is significantly different to the mean of the 20% reduction condition at that time point (mixed effects models): p<0.05. Addition of * to the letter indicates p<0.01 and ** indicates p<0.001.

Figure 5

Postprandial ratings (mean ± SEM) for A) perceived hunger, B) perceived fullness, C) perceived desire to eat, and D) perceived prospective consumption, according to condition. ‘a’ indicates the mean of the condition is significantly different to the mean of the control condition at that time point. ‘b’ indicates the mean is significantly different to the mean of the 20% reduction condition at that time point (mixed effects models): p<0.05. Addition of * to the letter indicates p<0.01 and ** indicates p<0.001.