Physical development at 7 years of age in relation to velocity of weight gain in infancy with special reference to incidence of overweight.

As a result of a carefully controlled study on obese children, Borjeson (1962) concluded that obesity in childhood is not a problem of physical health, and that although it may be a major psychological problem for some children, in most cases there is no evidence of emotional conflict caused by obesity itself. Nevertheless, most physicians consider obesity in children to be a major health problem calling for preventive and therapeutic action. Besides a wide spread moral attitude towards overconsumption of food as the suspected cause of overweight, this concern gains support from the claim that obesity in adults implies a considerably increased risk of secondary disease and premature death (Kannel et al, 1967) and the fact that very often adult obesity starts in childhood (Mullins, 1958). In the view of physicians responsible for adult care, treatment of obesity should therefore start in childhood. Paedia tricians, however, have all experienced extreme difficulties in endeavours to achieve long-term weight reduction in obese children (Lloyd, Wolff, and Whelen, 1961; Spranger and Dorken, 1967; Lodi, 1970). Therefore the possibility of early preventive action, preferably in infancy, has to be considered seriously. This preventive attitude has been supported by the findings of Knittle and Hirsch (1968) that the number of fat cells in adipose tissue is significantly increased in rats overfed during the first 10 weeks of life. It is not yet known whether human infants behave in the same way as rats in this respect. It has been found in the human species as well as in the rat, however, that the total number of fat cells in adult life cannot be reduced (Bjorntorp and Sjostrom, 1971). In a study on obese children and adults published recently, Brook, Lloyd, and Wolff (1972) showed that the early onset of obesity is associated with an increased number of fat cells. In a longitudinal study in Sheffield, England, Eid (1970) found a significantly increased incidence of overweight and obesity in those children who had gained weight rapidly during the first six months of life, as compared with normally growing infants. However, these results may not be representative for a 'normal' population, since it was shown later by Taitz (1971) that no less than 60% of artificially fed infants from the same region gained weight above the 90th centile of generally accepted British standards. In Sweden the physical life conditions have for a long time been fairly similar for the great majority of infants; the frequency of breast-feeding is generally low, and artificial nutrition has been highly standardized during the last decades. The market for baby food is completely dominated by two manu facturers, whose products are similar and in accord ance with the recommendations of leading paedia tricians. The information about infant nutrition provided by child welfare centres and private paediatricians is uniform throughout the country, and the attendance rate at the well baby clinics approaches 100%. In case of deviations from normal weight development, substantial efforts are made to correct errors in nutrition which may have occurred. The present investigation was started with the aim of finding out how many of the obese children in a representative population of school children started as 'rapidly weight gaining' infants, and how many of such infants in a representative infant population will eventually be obese, if infant nutrition is fairly well controlled by a uniform programme.