Short-term effects of a fiber–protein functional product on subjective appetite and calorie intake

Abstract

Overweight and obesity are rising global health concerns, contributing to increased metabolic and cardiovascular diseases. Among the multiple factors influencing body weight, dietary intake plays a critical role. Designing functional foods that enhance satiety and reduce energy intake is a promising strategy to support weight management. This study aimed to develop and optimize a protein- and fiber-enriched snack and evaluate its effects on appetite and food intake. Whey protein, casein, and egg albumin were combined with fibers such as inulin, oligofructose, glucomannan, and apple fiber to formulate 17 different samples. Sensory evaluation by semi-trained panelists assessed taste, texture, color, and overall acceptability, and the optimal formulation contained 30.3% protein and 11.6% fiber. A randomized, controlled, single-blind clinical trial was conducted on 40 healthy adults (BMI 19–25 kg/m²), divided into intervention (optimized product) and control (placebo) groups. Appetite was measured using a 100-mm visual analogue scale, and food intake was recorded during an ad libitum lunch 3.5 hours after snack consumption. Results demonstrated that the optimized product significantly influenced hunger, fullness, desire to eat, and overall appetite score (p<0.05). Effect size analysis indicated moderate effects on hunger and fullness and a large effect on desire to eat, while actual food intake was minimally affected. In vitro evaluation suggested that fiber–protein interactions increased viscosity and gastric retention, delaying digestion and potentially enhancing satiety signaling. In conclusion, the optimized fiber- and protein-enriched product improved appetite regulation, primarily by enhancing satiety, though its impact on immediate food intake was limited, highlighting its potential as a functional food for weight management