(Reuters Health) - Young men who are overweight or obese have up to double the risk of normal-weight peers for developing liver disease later in life, a large study in Sweden suggests.
If the young men also had type 2 diabetes, their risk of having liver disease by the time they reached middle age was as much as 3.3 times higher, researchers report in the journal Gut.
Past studies have shown that diabetes raises risk for liver disease and liver cancer, but the current study indicates that having a high body mass index (BMI), a measure of weight relative to height, is a risk factor on its own.
“A high BMI early in life in men is associated with an increased risk of developing severe liver disease later in life, and this cannot be explained by a high alcohol consumption or viral hepatitis,” lead study author Dr. Hannes Hagstrom told Reuters Health by email.
"Also, this risk was highly increased in those men who contracted type 2 diabetes during the follow-up, independent of the baseline BMI,” said Hagstrom, a researcher with the Center for Digestive Diseases at Karolinska University Hospital in Stockholm.
The study team analyzed records for 1,220,261 men who had physicals when they were drafted into the Swedish army between 1969 and 1996 and were 17 to 19 years old at the time. Using national health registries, the researchers followed the men until 2012.
They grouped men according to BMI, which is measured as kilograms per square meter. Normally, a BMI between 18.5 and 24.9 is considered a healthy weight, while 25 to 29.9 is overweight, 30 or above is obese and 40 or higher is what's known as morbidly obese. In the current study, researchers reduced the healthy range to BMIs between 18.5 and 22.5, and used men in that group as the basis for comparisons with all the others.
When the men were drafted, the average BMI was 21.5, and just 100,000 men were in the overweight range and 20,000 qualified as obese. But rates of obesity differed across the original enlistment period, the researchers note. In 1969, about 6 percent of men were overweight and less than 1 percent were obese, but by 1996, 12 percent of young men were overweight and almost 3 percent were obese.
Over the follow-up period, 5,281 men developed severe liver diseases, including cirrhosis and liver failure, and 251 were diagnosed with liver cancer.
When compared to men with BMIs less than 22.5 at baseline, the risk of severe liver disease increased as BMIs went up: men in the overweight category had about 50 percent increased risk of liver disease and obese men had a two-fold increased risk. Excluding men with a diagnosis of alcoholic liver disease from the analysis raised the risk associated with obesity slightly higher still.
"Although we cannot know for sure, we speculate that these men had or developed non-alcoholic fatty liver disease, and that this in some cases led to severe liver disease,” Hagstrom said.
When they looked at liver cancer, the researchers found that men who were overweight at baseline had about a 60 percent increase in risk, while the risk was more than tripled for men who were obese.
Hagstrom said physicians should know overweight and obese teenage boys are at an increased risk for future severe liver disease, and that intervention early in life likely is necessary to reduce this risk.
“Obesity is an important risk factor for a number of types of cancer. Liver cancer is one of those,” Karen Basen-Engquist told Reuters Health.
“This study shows that even obesity in early adulthood is associated with later risk. It's important for us to try to maintain a healthy weight all through our lives,” said Basen-Engquist, director of the University of Texas MD Anderson’s Center for Energy Balance in Cancer Prevention and Survivorship in Houston.
Basen-Engquist, who was not involved in the study, said doctors and researchers need to keep getting that message out because a lot of people aren't aware of the link between obesity and cancer. “A lot of people know about smoking and cancer, but they don't think about obesity and cancer risk.”
SOURCE: bit.ly/2nYYC0X Gut, online March 20, 2017.