Effects of adding carbohydrate to the diet under natural living conditions over 4 weeks: design of a study.

Abstract

Sugars may affect appetite and mood. Some researchers have suggested that ingested carbohydrates satiate appetite (e.g. Spitzer and Rodin, 1987, Appetite 8, 1355-145) and reduce arousal (Spring et al.,1983, Psychiatric Research 17, 155-167). However, other research has found carbohydrate to increase appetite (e.g. Geiselman and Novin, 1982, Science 218, 490-491). Few studies have controlled psychological factors or examined effects of consumption of sugars over more than 24 hour. Designs must also allow for the fact that people knowingly receiving sugar may behave according to their expectations (Reid and Hammersley, 1998, Psychology, Health and Medicine 3, 299- 313.). A study has been designed to test the following four hypotheses. (1) Sugar supplementation will reduce energy intake from other sources, specifically fat. (2) Sugarlabelled drinks will increase this effect. (3) Restrained women will be more responsive to labelling. (4) Sugar supplementation will not affect sweet food intake or hunger in the long-term. The study has involved 160 restrained and unrestrained females receiving such dietary supplementation for 4 weeks in a between-subjects 2 2 2 design (restrained or unrestrained subjects; sugar or diet drink formulations; drinks labelled sugar or diet). Measures included the Dutch Eating Behaviour Questionnaire, unweighed food diaries (using MAFF food atlases), mood ratings, body fat by impedance and blood lipids. Assessments were repeated weekly. The outcomes of such studies have implications for understanding of the processes by which people adapt to changes in their diets and of how food may influence mood and appetite.