U. NOTTINGHAM (UK) — Adults may be more at risk for health problems if they are lean as children and later become obese, new research suggests.
The findings are based on a systematic review of research into childhood obesity and metabolic disease in adult life. The review shows there is little evidence directly linking childhood obesity and heart disease and diabetes. The work, reported in the International Journal of Obesity, suggests there could even be a slight protective effect if we are overweight as children and reduce our Body Mass Index (BMI) in adulthood.
For the study, researchers reviewed 11 academic studies that considered the health of thousands of people living in westernized countries. When adult BMI was accounted for, people at the lower end of BMI in childhood who became obese later in life had the highest chances of high blood pressure, type 2 diabetes, and heart disease.
“There is substantial evidence that childhood obesity tracks into adulthood and it is clear that adult obesity puts us at higher risk of metabolic disease,” says Simon Langley-Evans, chair of human nutrition at the University of Nottingham. “We are not therefore suggesting that childhood obesity is without consequences.
Targeting childhood and adolescence for prevention and treatment of obesity is wholly appropriate in order to establish a healthy weight moving forward into the adult years.
“However, we have found that the nature of the relationship between early BMI and adult disease risk is very complex. People at the lower end of the BMI range in childhood and go on to be obese as adults seem to be at particular risk. Therefore, by focusing on children who are overweight or obese for the promotion of health weight management we may be missing an important at-risk group.”
Being overweight or obese is associated with a range of chronic diseases such as cardiovascular disease, type 2 diabetes, and certain cancers. The World Health Organization has estimated that around a third of coronary heart disease and ischemic strike cases are attributable to excess weight.
As the prevalence of excess weight and obesity continues to increase there are significant implications for population morbidity and mortality with the increase in childhood obesity of particular concern.
“We conducted the reviews because we were interested in the impact of obesity during childhood on long term disease risk. We were surprised to see that when we adjusted for adult body mass index the relationships disappeared and, in fact, many of them reversed,” says Sarah McMullen, lecturer in human nutrition.
“Our analysis of the research as a whole goes against many of the conclusions from the individual studies. Most surprising to us was the finding that it is those who are relatively lean in childhood but go on to be obese during adulthood who are at particular risk.
“We must be very clear about one thing—obesity does have a very negative impact on health in many different ways. We know that people who are obese during childhood are more likely to be obese as adults, and this has a direct impact on their health and wellbeing at that time.
“It is generally assumed that an earlier onset and longer duration of obesity is associated with a greater cardiovascular risk, which has increased concerns about childhood obesity trends.
“However, very important questions remain as to the nature of the relationship. For example it isn’t clear whether weight loss interventions in adult life can fully ameliorate the risks associated with childhood obesity or whether an independent effect of childhood obesity remains, irrespective of the degree of adult weight.”
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