The influence of higher protein intake and greater eating frequency on appetite control in overweight and obese men

Abstract

The purpose of this study was to determine the effects of dietary protein intake and eating frequency on perceived appetite, satiety, and hormonal responses in overweight/obese men. Thirteen men (age 51 +/- 4 years; BMI 31.3 +/- 0.8 kg/m(2)) consumed eucaloric diets containing normal protein (79 +/- 2 g protein/day; 14% of energy intake as protein) or higher protein (138 +/- 3 g protein/day; 25% of energy intake as protein) equally divided among three eating occasions (3-EO; every 4 h) or six eating occasions (6-EO; every 2 h) on four separate days in randomized order. Hunger, fullness, plasma glucose, and hormonal responses were assessed throughout 11 h. No protein x eating frequency interactions were observed for any of the outcomes. Independent of eating frequency, higher protein led to greater daily fullness (P < 0.05) and peptide YY (PYY) concentrations (P < 0.05). In contrast, higher protein led to greater daily ghrelin concentrations (P < 0.05) vs. normal protein. Protein quantity did not influence daily hunger, glucose, or insulin concentrations. Independent of dietary protein, 6-EO led to lower daily fullness (P < 0.05) and PYY concentrations (P < 0.05). The 6-EO also led to lower glucose (P < 0.05) and insulin concentrations (P < 0.05) vs. 3-EO. Although the hunger-related perceived sensations and hormonal responses were conflicting, the fullness-related responses were consistently greater with higher protein intake but lower with increased eating frequency. Collectively, these data suggest that higher protein intake promotes satiety and challenge the concept that increasing the number of eating occasions enhances satiety in overweight and obese men.

Figures

Figure 1

Perceived appetite and satiety throughout the 11-h testing days following the dietary protein and eating frequency treatments. *Main effects; P < 0.05. Period I: time 0-240 min; period II: time 240-480 min; period III: time 480-620 min.

Figure 2

Plasma glucose and insulin responses throughout the 11-h testing days following the dietary protein and meal frequency treatments. *Main effects; P < 0.05. Period I: time 0-240 min; period II: time 240-480 min; period III: time 480-620 min.

Figure 3

Plasma active ghrelin and total PYY responses throughout the 11-h testing days following the dietary protein and meal frequency treatments. *Main effects; P < 0.05. Period I: time 0-240 min; period II: time 240-480 min; period III: time 480-620 min.