To follow and predict the evolution of adiposity during growth, individual adiposity curves, assessed by the weight/height2 index, were drawn for 151 children from the age of 1 month to 16 yr. Adiposity increases during the 1st yr and then decreases. A renewed rise, termed here the adiposity rebound, occurs at about 6 yr. Individual weight/height2 curves may differ regarding their percentile range level and age at adiposity rebound. The present study shows a relationship between the age at adiposity rebound and final adiposity. An early rebound (before 5.5 yr) is followed by a significantly higher adiposity level than a later rebound (after 7 yr). This phenomenon is observed whatever the subject's adiposity at 1 yr. The present observations might be connected with the cellularity of adipose tissue.

Background: Protein intake during infancy was associated with rapid early weight gain and later obesity in observational studies. Objective: The objective was to test the hypothesis that higher protein intake in infancy leads to more rapid length and weight gain in the first 2 y of life. Design: In a multicenter European study, 1138 healthy, formula-fed infants were randomly assigned to receive cow milk-based infant and follow-on formula with lower (1.77 and 2.2 g protein/100 kcal, respectively) or higher (2.9 and 4.4 g protein/100 kcal, respectively) protein contents for the first year. For comparison, 619 exclusively breastfed children were also followed. Weight, length, weight-forlength, and BMI were determined at inclusion and at 3, 6, 12, and 24 mo of age. The primary endpoints were length and weight at 24 mo of age, expressed as length and weight-for-length z scores based on the 2006 World Health Organization growth standards. Results: Six hundred thirty-six children in the lower (n ¼ 313) and higher (n ¼ 323) protein formula groups and 298 children in the breastfed group were followed until 24 mo. Length was not different between randomized groups at any time. At 24 mo, the weight-forlength z score of infants in the lower protein formula group was 0.20 (0.06, 0.34) lower than that of the higher protein group and did not differ from that of the breastfed reference group. Conclusions: A higher protein content of infant formula is associated with higher weight in the first 2 y of life but has no effect on length. Lower protein intake in infancy might diminish the later risk of overweight and obesity. This trial was registered at clinicaltrials.gov as NCT00338689.

Childhood obesity is an important public health problem, with a rapidly increasing frequency worldwide. Identification of critical periods for the development of childhood and adolescent obesity could be very useful for targeting prevention measures. Weight status in early childhood is a poor predictor of adult adiposity status, and most obese adults were not obese as children. We first proposed to use the body mass index (BMI) charts to monitor individual BMI development. The adiposity rebound (AR) corresponds to the second rise in BMI curve that occurs between ages 5 and 7 years. It is not as direct a measure as BMI at any age, but because it involves the examination of several points during growth, and because it is identified at a time when adiposity level clearly change directions, this method provides information that can help us understand individual changes and the development of health risks. An early AR is associated with an increased risk of overweight. It is inversely associated with bone age, and reflects accelerated growth. The early AR recorded in most obese subjects and the striking difference in the mean age at AR between obese subjects (3 years) and non-obese subjects (6 years) suggest that factors have operated very early in life. The typical pattern associated with an early AR is a low BMI followed by increased BMI level after the rebound. This pattern is recorded in children of recent generations as compared to those of previous generations. This is owing to the trend of a steeper increase of height as compared to weight in the first years of life. This typical BMI pattern (low, followed by high body fatness level) is associated with metabolic diseases such as diabetes and coronary heart diseases. Low body fatness before the AR suggests that an energy deficit had occurred at an early stage of growth. It can be attributable to the high-protein, low-fat diet fed to infants at a time of high energy needs, the former triggering height velocity and the latter decreasing the energy density of the diet and then reducing energy intake. The high-fat, low-protein content of human milk may contribute to its beneficial effects on growth processes. Early (pre-and postnatal) life is a critical period during which environmental factors may programme adaptive mechanisms that will persist in adulthood. Under-nutrition in fetal life or during the first years after birth may programme a thrifty metabolism that will exert adverse effects later in life, especially if the growing child is exposed to overnutrition. These observations stress the importance of an adequate nutritional status in childhood and the necessity to provide nutritional intakes adapted to nutritional needs at various stages of growth. Because the AR reflects particular BMI patterns, it is a useful tool for the paediatrician to monitor the child's adiposity development and for researchers to investigate the different developmental patterns leading to overweight. It contributes to the understanding of chronic disease programming and suggests ne...

On the basis of a longitudinal study of growth in French children, we attempted to find a valid index for estimating adiposity, and to specify the optimal conditions for its use. The Quetelet index was found suitable for application to children, but as with all methods, a certain lack of precision proved unavoidable because of the different stages of growth observed at a given age. For use by clinicians, we provide charts, based on the Quetelet index and on age, permitting estimation of adiposity in any child on the basis of longitudinal study measurements. For use by epidemiologists, we give standard values for studying groups of subjects, even when a reference population is not available. Body adiposity may be expressed independently of age and sex.

Since the concept of lasting programming effects on disease risk in human adults by the action of hormones, metabolites, and neurotransmitters during sensitive periods of early development was proposed >3 decades ago, ample supporting evidence has evolved from epidemiologic and experimental studies and clinical trials. For example, numerous studies have reported programming effects of infant feeding choices on later obesity. Three meta-analyses of observational studies found that obesity risk at school age was reduced by 15-25% with early breastfeeding compared with formula feeding. We proposed that breastfeeding protects against later obesity by reducing the occurrence of high weight gain in infancy and that one causative factor is the lower protein content of human milk compared with most infant formula (the early protein hypothesis). We are testing this hypothesis in the European Childhood Obesity Project, a double-blind, randomized clinical trial that includes >1000 infants in 5 countries (Belgium, Germany, Italy, Poland, and Spain). We randomly assigned healthy infants who were born at term to receive for the first year infant formula and follow-on formula with higher or lower protein contents, respectively. The follow-up data obtained at age 2 y indicate that feeding formula with reduced protein content normalizes early growth relative to a breastfed reference group and the new World Health Organization growth standard, which may furnish a significant long-term protection against later obesity. We conclude that infant feeding practice has a high potential for long-term health effects, and the results obtained should stimulate the review of recommendations and policies for infant formula composition.

The development of adiposity was followed in 164 subjects from the age of one month to adulthood. The 25th and 75th centiles of the weight/height2 (W/H2) index were chosen as cut-off points to define the lean, medium and fat subjects at both one and 21 years of age. Only 42% of the children remained in their original category, that is 41% of the lean infants at one year stayed lean, 42% of the medium infants stayed medium and 41% of the fat infants stayed fat. Accordingly, most fat infants did not stay fat, but twice as many fat as non-fat infants became fat adults (41 and 20% respectively). The relative risk of being fat adults was 1 for the lean, 1 for the medium and 2 for the fat infants at one year. Several paths of development emerged: they were related to age at the second rise in adiposity, termed adiposity rebound, which usually occurs at about six years, as observed on skinfold thickness and W/H2 charts. The earlier the rebound, the higher the adiposity at adult age, whether this was measured by W/H2 index or subscapular skinfold. The cohorts of children who left the channel they had been following included fat infants with a late rebound who subsequently returned to normal, and lean infants with an early rebound who grew fatter. Other cohorts remained in their original groups, for example, fat infants with an early rebound who stayed fat and lean infants with a late one who stayed lean. Age at rebound provided two indications: the existence of a regulartory process among the transiently fat or lean infants who returned to average after a late or early rebound respectively, and pathological development among the children who became fat or lean after an early or late rebound. Age at rebound is an indicator of the subsequent development of fatness.

Childhood obesity is considered a major issue because of its high prevalence and because of its severe consequences on adult health. Prevalence studies are carried out in numerous countries. Analysis of time trends and geographic comparisons are particularly useful, as they may help to identify factors promoting obesity. These studies require adequate definitions of nutritional status and standardized protocols, but in practice, the references, cut-offs and the terminology used vary considerably, and consequently ambiguous information may be found in the literature. Recommendations for the definition of childhood obesity were previously published in 1995 by the European Childhood Obesity Group (ECOG), but new references appeared later. A clarification of the different definitions was needed. Currently used classifications of nutritional status in children are summarized, and recommendations for the references, cut-offs and terms to be used in different contexts are provided. These new ECOG recommendations should help harmonize the various protocols and improve comparisons between studies.

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