EFFECTS OF FAT-CONTENT, WEIGHT, AND ACCEPTABILITY OF THE MEAL ON POSTLUNCH CHANGES IN MOOD, PERFORMANCE, AND CARDIOVASCULAR FUNCTION

This study examined the effects of fat content and meal size on postlu nch changes in mood, performance, and cardiovascular function. Forty-s ix subjects (20 males, 26 females) were tested before and after lunch. Subjects were assigned to one of the following lunch conditions: a) l ow fat (23 g), large meal (860 g); b) low fat (18 g), small meal (600 g); c) high fat (84 g), large meal (840 g); d) high fat (79 g), small meal (530 g). The results showed only small effects of fat composition and meal size, with no cardiovascular effects being observed and no e vidence of fat content or the weight of the meal influencing performan ce of logical reasoning or cognitive vigilance tasks. A few effects of meal type were significant in the mood data, but given the large numb er of analyses conducted, these could represent chance effects. Result s from two selective attention tasks showed that subjects given the hi gh-fat meals responded more slowly but more accurately, which differs from the effects of carbohydrate, protein, and calorie content reporte d in earlier papers. Weight of the meal influenced the degree of distr action from near and far distracters and also the accuracy of response s to central and peripheral targets. However, both the effects of fat and meal size were modified by task parameters, and further research i s required before firm conclusions can be drawn about the functional i mportance of the influences of nutrient content and meal size on perfo rmance. The high-fat and large meals were rated as more acceptable tha n the low-fat and small meals. These differences in acceptability coul d not, however, account for the changes in performance observed after consumption of the different meal types.