Macronutrients and appetite control with implications for the nutritional management of the malnourished

Altered appetite is one of the most frequently cited yet poorly understood symptoms encountered in the clinical setting. This review critically discus ses the constraints under which macronutrient balance is physiologically re gulated, the nature of appetite control and feeding behaviour in humans, ho w dietary macronutrients influence appetite control and feeding behaviour, the role of macronutrient metabolism and stores as putative signals that ca n influence appetite, energy intake and balance, and the importance of stud ying undernutrition as a reference for studies of appetite in the clinical setting in order to develop effective therapies for malnutrition (over and undernutrition). The following general conclusions were reached: (1) there seems to be a hierarchy in the extent to which individual macronutrient bal ances are regulated and the extent to which dietary macronutrients suppress subsequent energy intake (in both cases protein > carbohydrate > fat); (2) the oxidation of individual nutrients is monitored both by the central and peripheral nervous system but the relative importance of the two systems i s unclear; (3) recent work on body weight regulation has placed much more e mphasis on signals arising from adipose tissue than other potentially power ful signals arising from lean tissue; (4) in disease-related malnutrition, loss of both lean and adipose tissue is often not associated with increased appetite sensations and food intake probably because of complex interactio ns between inflammatory mediators such as cytokines, neuroendocrine abnorma lities, drug (and other) therapies, and incompletely understood effects of psychological and metabolic disturbances. (C) 2001 Harcourt Publishers Ltd.