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 andcardiovascular diseases. Among the multiple factors influencing body weight, dietary intake plays acritical role. This study aimed to develop and optimize a snack enriched with protein and fiber toevaluate its effects on appetite and subsequent food intake. Whey protein, casein, and egg albuminwere combined with fibers such as inulin, oligofructose, glucomannan, and apple fiber to formulatedifferent samples. Sensory evaluation by ten semi-trained panelists assessed taste, texture, color, andoverall acceptability, and the optimal formulation contained 30.3% protein and 11.6% fiber. Arandomized, controlled, single-blind clinical trial was conducted on 40 healthy adults (BMI 19–25kg/m²), divided into intervention product and control (placebo) groups. Appetite was measured usinga 100-mm visual analogue scale, and food intake was recorded during an ad libitum lunch 3.5 h aftersnack consumption. Results demonstrated that the optimized product significantly influencedhunger, fullness, desire to eat, and overall appetite score (p<0.05). Effect size analysis indicatedmoderate effects on hunger and fullness and a large effect on desire to eat, while actual food intakewas minimally affected (small effect size: d<20). In vitro evaluation suggested that fiber–proteininteractions increased viscosity and gastric retention, delaying digestion and which may enhancesatiety signaling. In conclusion, the optimized high-protein, high-fiber snack improved appetiteregulation mainly by enhancing satiety, although its effect on immediate food intake was limited,supporting its potential as a functional food for weight management