Early growth and obesity risk – What should health professionals be advising?

Obesity rates in the UK have been continuously increasing among adults and children and have been attributed to nutritional and lifestyle practices that promote a positive shift in energy balance. Over the last few decades, a growing body of evidence suggests that the origins of obesity start at the earliest stages of human development and specifically pre‐conception, in utero and during early infancy. Maternal nutritional status and early life feeding have been identified as ‘critical windows’ for obesity risk. Pre‐conception and pregnancy overweight and obesity, as well as fetal exposure to diabetes and hyperglycaemia, have been associated with high birthweight, which, in turn, has been reported to have a direct link with obesity risk later in life. A number of studies have also demonstrated low birthweight to be associated with increased risk of obesity and suggested that low‐birthweight term infants who demonstrate early ‘catch‐up’ growth have a tendency to become obese adults. Low birthweight has been associated with pre‐conception underweight and inadequate in utero nutrition. Although the links between early growth and later obesity risk implicate maternal pre‐natal nutrition, it has been suggested that nutrition during early infancy also affects later body composition. Breastfeeding has been associated with a reduced prevalence of obesity, although the evidence is still inconsistent and somewhat limited. Recent advances in the ability to manipulate infant formula composition by reducing its protein content and bringing its composition closer to that of breastmilk could potentially help prevent the rapid weight gain observed in formula‐fed infants. Early introduction of complementary foods has also been associated with increased obesity risk later in life. Unfortunately to date, the majority of evidence on the developmental origins of obesity comes from observational studies, making their interpretation difficult and providing an uncertain basis for practice. However, a number of modifiable risk factors in the pre‐natal and early post‐natal periods of human development have been identified, as well as vulnerable subgroups within the population to these risk factors, which may guide health professionals when advising women regarding lifestyle strategies to reduce the risk of obesity for their offspring and for future generations.