Influence of genetic taste sensitivity to 6-n-propylthiouracil (PROP), dietary restraint and disinhibition on body mass index in middle-aged women

A previous study from our laboratory reported a small, inverse association between taste sensitivity to 6-n-propylthiouracil (PROP) and body mass index (BMI) among lean, young-adult males. Weaknesses in study design precluded making this same observation in females. To overcome these shortcomings, the present study investigated this relationship in older, heavier women characterized by dietary restraint and disinhibition. We tested the hypothesis that lower taste sensitivity to PROP would be associated with higher BMI but that high dietary restraint would mask this association. Thus, no relationship between taster status and BMI was expected in those with high dietary restraint. Eighty-six, middle-aged women (39.0+/-1.0 years) with a mean BMI of 27.4+/-0.8 participated. They were classified as PROP nontasters (n=23), medium tasters (n=32) or supertasters (n=31). Initial analyses revealed that disinhibition had a strong positive influence on BMI that was unrelated to PROP status (P< or =.001). After adjusting for disinhibition, a strong interaction between PROP status and restraint on BMI was noted. Among women with low dietary restraint, nontasters (P< or =.01) and medium tasters (P< or =.05) were heavier than supertasters by 6 and 4 adjusted BMI units, respectively. No differences in BMI were found across taster groups in women with high dietary restraint. These data confirm that the inverse association between PROP status and BMI reported earlier in men is also present in women and that this relationship becomes apparent when variables relevant to eating behavior in women are taken into consideration. These findings are discussed in the context of emerging theories relating genetic differences in taste to fat acceptance, fat intake and body weight.