Adult diseases may be linked to childhood weight

Being fat isn’t fun for anyone, especially children and teens. It’s not healthy either. Obesity that develops in childhood can set the stage for killer adult diseases, two new studies from Denmark show.

Past studies had shown that being overweight or obese boosts an adult’s risk of developing health problems affecting the heart and brain. But no one had shown that the same was true when that weight gain occurred in childhood. Now two new studies appear to do just that. Both were presented this month at the European Obesity Summit in Gothenberg, Sweden.

Researchers tend to assess obesity on the basis of more than weight alone. After all, for the same weight, a tall person will be leaner than a short person. So height, too, is key. Both height and weight go into calculating someone’s body mass index, or BMI. And the higher the BMI, the fatter a person tends to be.

Line Klingen Haugaard studies childhood obesity and how it affects health. She works at the University of Copenhagen in Denmark. Her team focused on health records for 307,000 Danes who had been born between 1930 and 1987. More than 3,500 of the women and almost 5,400 of the men at one time had suffered an ischemic (Ih-SKEEM-ik) stroke. This is where blood stops flowing to a part of the brain. Such strokes can prove deadly.

The researchers looked back at the early school records for all of the adults. They calculated the BMI for each of the men and women when they had been only 7 to 13 years old. (Denmark is one of the few nations that can do this, because its government keeps detailed, long-term health records for its citizens.)

People who had a higher BMI by age 13 faced a higher than normal risk of early stroke in adulthood, the researchers found. Early, in this case, means that a person had a stroke sometime between the ages of 25 and 55. After 55, childhood BMI appeared to play no role in stroke risk.

Consider a middle-school girl who was 156.7 centimeters (62 inches) tall and weighed 51.4 kilograms (113 pounds). Compared with a girl who was the same height but weighed 6.8 kilograms (15 pounds) less, the first girl’s adult risk of stroke would be 26 percent higher. A similar trend emerged in adult men who had been overweight as boys.

And as the BMI in childhood climbed, so did the early stroke risk that was seen in someone’s adult years, the new study found.

What might explain this? A higher BMI could cause the brain’s blood vessels to slowly harden and narrow, beginning in childhood, Haugaard suspects. And that, she worries, could disrupt the flow of blood to the brain, fostering an ischemic stroke in early to middle adulthood.

“If you have already reached the age of 55, other factors responsible for stroke become more important than any childhood factors,” says Haugaard. By other factors, she means diseases such as high blood pressure and type 2 diabetes. (High blood pressure occurs when blood flows with too much force through blood vessels. Type 2 diabetes is a condition when the body is not able to use a hormone called insulin. This hormone is important for the body to process glucose. People who have type 2 diabetes have abnormal levels of glucose in their blood, but also high risks of heart disease.)

Adult cancer risk also linked to overweight childhood

A second study also focused on Danish adults who had been overweight between the ages of 7 to 13. These people faced a heightened risk of colon cancer. This disease, which affects the biggest part of the large intestine, accounts for 8.3 percent of all U.S. cancer deaths. Any abnormal growth of cells in this part of the body might develop into a cancer.

Britt Wang Jensen works at Bispebjerg and Frederiksberg Hospital in Copenhagen. She and her colleagues gathered childhood BMI data for about 250,000 people born between 1930 and 1972. They then linked those data with national records on cancer patients.

Nearly 2,700 people from the original group developed colon cancer. And the higher their childhood BMI had been, the higher an adult’s risk of colon cancer turned out to be. Here’s another way to understand the findings: Let’s compare two boys — Jack and Tom — who were both born in the 1950s. They had the same height. Jack had an average weight. Tom weighed 5.9 kilograms (13 pounds) more than him. In adulthood, Tom had a 9 percent higher risk of colon cancer than Jack.

Stephen Daniels is a doctor who treats kids at the University of Colorado School of Medicine in Aurora. He was not involved with either study. He says the new findings are important and fit with what might be expected.

“The major strengths of the two studies are the large populations and the lengths of the follow-ups,” says Daniels. Some of the people in these studies were followed until they died. Daniels explains that it’s hard for scientists to track people for such a long time. That’s why these studies are important.

Both studies point to why it’s important to maintain a healthy weight at every age. Indeed, says Daniels, eating well in childhood and maintaining healthy levels of exercise are some of “the most important things for kids and their parents to think about.”