|Activity, Energy Expenditure and Energy Requirements of Infants and Children (International Dietary Energy Consultative Group - IDECG, 1989, 412 pages)|
|The desirable upper limits of energy intake in childhood: Short- and long-term consequences|
There is now a mass of evidence to support the concept that a heavy child is likely to grow into an overweight adult. It has been known for many years that obese children tend to become obese adults. For example, HAASE and HASENFELD (1958) found that 80% of overweight children remained markedly overweight when reexamined 20-30 years later; LLOYD, WOLF and WHELEN (1961) also found a majority of obese children entering adolescence aged 9-11 years remaining obese over the subsequent eight years. A larger study by ABRAHAM and NORDSEICK (1960) showed that 80% of obese 10- to 13-year olds were still overweight 26-35 years later. In this study, the normal-weight adolescents had a different outcome, with smaller fluctuations in weight and fewer becoming overweight in adult life.
Even longer-term follow-up studies over a period of 40 years have recently been reported from Sweden by MOSSBERG (1989). Childhood obesity persisted with 47% of the obese children remaining obese in later life. Most (85%) of these obese adults had been markedly overweight in childhood, i.e., weighing more than two standard deviations above the average for the age and sex of Swedish children. Parental and pubertal obesity seemed to amplify the poor health prognosis as did early excessive obesity. The last point was already evident from the substantial insurance data which emphasize the deleterious effects of obesity of early onset (BLAIR and HAINES, 1966).
These studies therefore strongly favour the concept that excessive weight, once established in childhood, tends to persist. MELBIN and VUILLE (1976) also found that rapid weight gain in infancy was significantly associated with overweight in adolescent boys, the same trend being observed in girls. On this basis the studies on infant growth rates and adult obesity may be linked to imply that infant growth patterns could identify those individuals with a greater propensity to adult obesity.
CHARNEY et al. (1976) showed just this phenomenon: 36% of infants below 6 months of age who exceeded the 90th centile by weight became overweight adults when studied 20-30 years later, and only 14% of average-weight or light-weight infants became overweight adults. The link between infant and adult weights were evident once the recognized influences of social class, educational level and parental weight on adult adiposity had been taken into account.
These findings could lead to the conclusion that excessive overfeeding in childhood leads to rapid weight gain and this then entrains a very high risk of adult obesity. An alternative explanation, however, is that the prevailing conditions conducive to weight gain operate in both childhood and adult life so that those susceptible members of society manifest their obesity both in infancy when they are overfed by their mothers and later in adult life when they fail to maintain their usual activity patterns or overeat for other social reasons.
If the second hypothesis is correct, then social conditions and personal approaches to weight stability may be more successful than a metabolic entraining of metabolism implied by the first explanation. KID (1970) and POSKITT and COLE (1977) showed that persisting infantile adiposity was not inevitable and that only a minority of heavy infants remained obese either at 6-8 years of age or even earlier at 4-5 years. The real question remains therefore one of assessing whether infant feeding can modify the degree of adiposity in adult life and whether by this or other mechanisms weight gain can be considered as a predictor of long-term health.