The effect of breakfast on mood, appetite and cognitive function : modifying influences of breakfast and diet composition

Short term food choices can affect not only hunger, but can also affect mood and cognitive function, yet few studies have measured all three factors in a single study. The macronutrient composition of breakfast and diet influences mood, appetite and cognitive function. This thesis describes a series of studies in healthy female subjects investigating the effects of breakfast, and manipulations of breakfast and diet composition on mood, appetite and cognitive function. In these studies subjects were provided with high fat, low carbohydrate (HFLC) and low fat, high carbohydrate (LFHC) breakfasts and diets. Study 1 found that breakfast provision (LFHC breakfast), in comparison to breakfast omission resulted in significant improvements in subjects' self reported ratings of mood and appetite, which were closely correlated with each other. Breakfast provision did not cause any significant changes in cognitive function, but this may be as a result of insufficiently demanding tests. The macronutrient composition of the breakfasts was modified in study 2 which found that the HFLC breakfast reduced subjective feelings of anger, reduced target reaction times and prevented a deterioration in the letter x accuracy task in comparison the LFHC breakfast. The HFLC and LFHC breakfast differed from subjects habitual breakfast composition. Study 3 and study 4 found that habitual breakfast consumption (in comparison to the HFLC and LFHC breakfasts) resulted in a much greater increase (relative to baseline) in subjective ratings of energy and placidity, a greater reduction in ratings of tiredness and a reduction in reaction times. Study 4 also found that consumption of a HFLC diet for 2 weeks resulted in an increase in subjective ratings of energy, whilst consumption of a LFHC diet resulted in a reduction. Consumption of both diets resulted in a reduction in ratings of tense and an increase in ratings of placidity at the second study visits.EThOS - Electronic Theses Online ServiceGBUnited Kingdo