Slower eating speed lowers energy intake in normal-weight but not overweight/obese subjects.

Background: The effect of eating speed on energy intake by weight status is unclear.

Objective: To examine whether the effect of eating speed on energy intake is the same in normal-weight and overweight/obese subjects.

Design: The effect of slow and fast eating speed on meal energy intake was assessed in a randomized crossover design.

Participants/setting: Thirty-five normal-weight (aged 33.3±12.5 years; 14 women and 21 men) subjects and 35 overweight/obese (44.1±13.0 years; 22 women and 13 men) subjects were studied on 2 days during lunch in a metabolic kitchen.

Intervention: The subjects consumed the same meal, ad libitum, but at different speeds during the two eating conditions. The weight and energy content of the food consumed was assessed. Perceived hunger and fullness were assessed at specific times using visual analog scales.

Statistical Analyses: Effect of eating speed on ad libitum energy intake, eating rate (energy intake/meal duration), energy density (energy intake per gram of food and water consumed), and satiety were assessed by mixed-model repeated measures analysis.

Results: Meal energy intake was significantly lower in the normal-weight (804.5±438.9 vs 892.6±330.2 kcal; P=0.04) but not the overweight/obese (667.3±304.1 vs 724.8±355.5 kcal; P=0.18) subjects during the slow vs the fast eating condition. Both groups had lower meal energy density (P=0.005 and P=0.001, respectively) and eating rate (P<0.0001 in both groups) during the slow vs the fast eating condition. Both groups reported less hunger (P=0.01 and P=0.03, respectively), and the normal-weight subjects reported more fullness (P=0.02) at 60 minutes after the meal began during the slow compared with the fast eating condition. There was no eating speed by weight status interaction for any of the variables.

Conclusions: Eating slowly significantly lowered meal energy intake in the normal-weight but not in the overweight/obese group. It lowered eating rate and energy density in both groups. Eating slowly led to lower hunger ratings in both groups and increased fullness ratings in the normal-weight group at 60 minutes from when the meal began.