British Journal of Nutrition

Behaviour, appetite and obesity

Body composition and appetite: fat-free mass (but not fat mass or BMI) is positively associated with self-determined meal size and daily energy intake in humans

John E. Blundella1 c1, Phillipa Caudwella1, Catherine Gibbonsa1, Mark Hopkinsa2, Erik Näslunda3, Neil A. Kinga4 and Graham Finlaysona1

a1 Biopsychology Group, Institute of Psychological Sciences, University of Leeds, Leeds LS2 9JT, UK

a2 Sport, Health, Leisure and Nutrition, Leeds Trinity University College, Brownberrie Lane, Horsforth, Leeds, UK

a3 Clinical Sciences (Division of Surgery), Danderyd Hospital, Stockholm, Sweden

a4 Human Movement Studies & Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia

Abstract

The idea of body weight regulation implies that a biological mechanism exerts control over energy expenditure and food intake. This is a central tenet of energy homeostasis. However, the source and identity of the controlling mechanism have not been identified, although it is often presumed to be some long-acting signal related to body fat, such as leptin. Using a comprehensive experimental platform, we have investigated the relationship between biological and behavioural variables in two separate studies over a 12-week intervention period in obese adults (total n 92). All variables have been measured objectively and with a similar degree of scientific control and precision, including anthropometric factors, body composition, RMR and accumulative energy consumed at individual meals across the whole day. Results showed that meal size and daily energy intake (EI) were significantly correlated with fat-free mass (FFM, P values < 0·02–0·05) but not with fat mass (FM) or BMI (P values 0·11–0·45) (study 1, n 58). In study 2 (n 34), FFM (but not FM or BMI) predicted meal size and daily EI under two distinct dietary conditions (high-fat and low-fat). These data appear to indicate that, under these circumstances, some signal associated with lean mass (but not FM) exerts a determining effect over self-selected food consumption. This signal may be postulated to interact with a separate class of signals generated by FM. This finding may have implications for investigations of the molecular control of food intake and body weight and for the management of obesity.

(Received February 09 2011)

(Revised April 21 2011)

(Accepted May 09 2011)

(Online publication July 07 2011)

Correspondence:

c1 Corresponding author: Professor J. E. Blundell, email j.e.blundell@leeds.ac.uk

Abbreviations: EE, energy expenditure; EI, energy intake; FFM, fat-free mass; FM, fat mass

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