Overnutrition or energy imbalance is a major problem in civilised communities. The energy potential of food depends not only on its energy content but also on its satiating capacity. In removing fibre from carbohydrate foods man creates foods which are artificially low in satiety. This has been demonstrated by compariso ns of equivalent meals of apple juice and whole apples and of white and wholemeal bread. Simply disruptit1g fibre by turning apples into a purée also reduces their satiety potential. Insulin is a hormone which favours the synthesis and deposition of fat. Fibre-depleted apple juice evokes a greater insulin response than whole apples, while purée has an intermediate effect. Refined carbohydrate probably causes hyperinsulinism by being readily and rapidly absorbed. This provides a further link between such foods and obesity, as well as a possible mechanism for the causation of diabetes and atherosclerosis.