Research has shown that consuming breakfasts high in either fat or carbohydrates can affect a persons memory, mood and ability to concentrate (Benton & Parker, 1998, Politt & Mathews, 1998). Our previous study investigating the effect of a high fat, low carbohydrate (HFLC) meal in comparison to a low fat, high carbohydrate (LFHC) meal found that the HFLC meal resulted in significantly increased feelings of calmness, friendliness and a reduction in feelings of anger, and an increase in subjective energy levels in comparison to a LFHC meal. However, the chronic effects of a HFLC or LFHC diet has not been studied. This purpose of this study is to investigate whether a 2 week diet high in either fat or carbohydrates improves cognition/memory and mood. It is hypothesised that the prolonged feeding of a HFLC diet will attenuate the response seen after a HFLC meal was provided.