The domestic chicken, Gallus domesticus, is recognized as an efficient source of lean meat. Genetic selection has resulted in large body size strains that grow rapidly. Concomitant with development of these desirable characteristics is increased abdominal fat deposition and altered body composition. Adipose cellular development in different genetic groups shows that abdominal adipocyte cell number as a proportion of body mass decreases as body size increases, concurrent with increased adiposity. Adipocyte hypertrophy explains a large proportion of the variation in abdominal fat percentage. Growth hormone is correlated with the number and size of abdominal adipocytes across genotype, sex and age. Adipose tissue development and body composition are affected by hormone levels in growing chickens. Possible approaches to modulate fat deposition and adipose cellularity in poultry are reviewed.