Growth trajectories associated with adult obesity

The influence of early life factors on later body weight and metabolic diseases has generated increasing interest in the recent years. Exposure to environmental factors during pregnancy and early life can exert long-lasting influence on health. Anthropometric indicators are of great value to investigate the early determinants of the development of obesity. Different indicators may be associated with different growth patterns and then may predict different risks. The adiposity rebound (AR) which corresponds to the second rise in BMI that occurs at around 6 years of age, predicts later body weight. An early rebound is a risk factor for later overweight. Many fat children stay fat but, by contrast, an early AR is not associated with overweight in early life. These observations point out the existence of various BMI patterns associated with adult obesity. Two main trajectories emerge: the trajectory of high BMI at all ages which reflects both high lean and fat body masses, and the trajectory of low or normal BMI followed by an early AR and a subsequent rise in BMI reflecting increased fat rather than lean body mass. The trajectory of always high BMI could correspond to the so-called 'metabolically healthy obese subjects' while the trajectory of low BMI followed by increasing fatness is associated with insulin resistance and coronary heart diseases. The very early rebound recorded in most obese subjects suggests that determinants of obesity have operated very early in life. The identification of growth trajectories is of great interest to investigate the factors promoting obesity and metabolic diseases and to improve prevention strategies which should start from early life.