Big babies and infants who gain weight very quickly early in life have a higher risk of suffering from obesity.

A review of 24 studies published online by the British Medical Journal on Friday showed that size early in life has a life-long impact.

"In the majority of studies the infants who were heaviest or those with the highest body mass index (BMI), and those who gained weight more rapidly in the first two years of life were more at risk of obesity," Dr Janis Baird, of the University of Southampton, in southern England stated.

"This was true for obesity in childhood, adolescence and adulthood."

Rates of obesity around the globe have been rising at an astounding rate. An estimated 155 million school-age children worldwide are overweight and about 35-40 million of that figure are obese, according to the International Obesity Task Force (IOTF).

Obesity is measured by dividing weight in kilograms by height in meters squared. A BMI of more than 25 for adults is overweight. Above 30 is considered obese.

Studies have also shown that infants who do not weigh much at birth but who catch up rapidly could also be more likely to grow into obese adults.

Baird said the results of the review were consistent across the studies which were done in the United States, Britain, other European countries and a couple of less developed nations.

The research covered people born between 1927 and 1994. "There were very consistent findings in all of the studies we looked at," Baird added. She and her colleagues do not know why big and fast growing babies had a higher risk of obesity. But they believe that some factors related to how an infant grows are important in influencing their later risk of obesity.

"What is needed are in-depth studies to try to understand better the pattern of growth in infancy and also to look at the factors that are associated with it," said Baird. She suggested that infant feeding, being bottle or breast fed, the timing of weaning and social circumstances were factors that should be studied.

"Research about the prevention of obesity should consider infancy, as well as childhood," Baird added. A lack of exercise, changing diets and bigger meals have been blamed for the rise in childhood obesity.

Health experts have said that ensuring women are properly nourished during pregnancy will help to ensure babies are born at the optimal weight and breastfeeding will give the baby the right nutrients for normal development.