Eating behaviour and retro-nasal aroma release in normal-weight and overweight adults: a pilot study

Eating rate and bite size are important factors affecting food intake, and we hypothesise the underlying role of oral sensory exposure in this. However, the latter currently lacks objective measuring parameters, but an interesting measure could be the extent of in vivo retro-nasal aroma release. Second, the literature is ambiguous about overweight subjects differing from normal-weight subjects in eating behaviour. Consequently, we investigated: (1) whether eating behaviour (food intake, eating rate, bite size, number of bites and meal duration) relates to weight status and (2) whether the extent of retro-nasal aroma release relates to eating behaviour and weight status. A matched group (sex, age and dietary restraint) of twenty-seven normal-weight (BMI 21.8 (SD 1.6) kg/m2) and twenty-seven overweight/obese subjects (BMI 30.5 (SD 5.8) kg/m2) consumed a spiced rice meal and apple pie yogurt on separate test days. The extent of retro-nasal aroma release was measured on a third test day. Mean bite size for spiced rice was significantly (P = 0.03) larger in overweight/obese (10.3 (SD 3.2) g) v. normal-weight subjects (8.7 (SD 2.1) g). There were no other significant differences in eating behaviour or retro-nasal aroma release between the groups. Eating behaviours were not correlated with BMI or retro-nasal aroma release. Subjects showed consistent eating behaviour for both test products. Eating behaviour might be a characteristic of an individual but not by definition a characteristic for a group of people based on their weight. Given the large sample sizes, necessary according to a posteriori sample size calculations, one needs to consider the relevance of finding a statistically significant difference in eating behaviour between the weight groups in a laboratory setting.