Teens who are overweight or obese have higher chances of eventually dying from heart disease, but that extra risk virtually vanishes if they trim down as adults.
That's according to a new study that tracked almost 19,000 men for more than 50 years, on average. All of them were Harvard University undergrads when they enrolled in the study.
"We have lots of data showing that if you are obese in middle age, it increases your risk of dying," said Dr I-Min Lee from Harvard Medical School in Boston, who worked on the study.
What we have less data on is what if you're heavy when you're younger? How does that impact your health later on?
Lower future risks
The findings, Dr Lee said, show that it's important to keep extra weight off in the first place – but if young adults are overweight, they can lower their future heart risks by slimming down.
The Harvard students had measurements of height and weight when they started college between 1916 and 1950.
In the 1960's, researchers followed up with 18,995 of the men and again asked about their height and weight, as well as other lifestyle habits and co- morbidities. At the time of those second surveys, participants' mean age was 46.
For the current study, a new group of researchers collected participants' death certificates and determined that about 11% of the men died from heart disease.
Excess risk goes away
Not surprisingly, being heavy at both the early and mid-life health checks increased the risk of cardiac mortality.
However, the extra heart risk that came with being overweight and obese early in life disappeared in men who were no longer heavy at their follow-up health assessment, the researchers reported October 25 in Archives of Internal Medicine.
Often, "obese young adults become obese middle-aged adults," Dr Lee told Reuters Health.
"However, if you're able to lose that weight, once you get to normal weight in middle age... the excess risk you had as a youngster goes away."
Number of years not important
Even people who are heavy in their 50s and 60s can ease their future heart risks by losing weight, Dr Lee added.
Dr Stephen Kritchevsky, who has studied weight loss in older adults at Wake Forest Baptist Medical Centre in Winston-Salem, North Carolina, agreed.
"The number of years being fat isn't as important as being overweight at middle age," he told Reuters Health. "At least through middle age, regardless of your life history, it is likely to be helpful to your health to try to lose weight."
Women not included
Dr Lee's team noted that the findings might not apply to women, since they weren't included in the study. Another limitation is that the study didn't distinguish where on their bodies different men carried their fat, which may affect the risk of heart disease.
Still, Dr Kritchevsky, who wasn't involved in the new study, said the findings are good news for both the young and old.
"For younger overweight people, it suggests that if you address that, it will pay off," he concluded. For that group, "it's not too early to address it, and for middle-aged people, it's not too late."
(Reuters Health, October 2011)