Blood pressure drugs feeding the obesity epidemic?

NEW YORK (Reuters Health) - Blood pressure drugs known as beta-blockers could be helping to fuel the obesity epidemic, by dampening the body’s ability to burn calories and fat over the long term, researchers say in a new report.

Weight gain is a known side effect of beta blockers, particularly older ones such as atenolol (Tenormin) and metoprolol (Lopressor, Toprol-XL). Newer versions, like carvedilol (Coreg), appear to carry less risk of added pounds.

Beta-blockers are not the only medications that promote weight gain. Antidepressants, corticosteroids and some diabetes medications are among the other culprits.

But with the growing problem of obesity worldwide, researchers are starting to look into the role that medications could be playing -- along with the usual suspects of poor diet and sedentary lifestyle.

In the new study, Australian researchers found that among more than 11,400 adults with high blood pressure and/or diabetes, those on beta-blockers weighed more, on average, and had larger waistlines.

And in a separate look at 30 patients with high blood pressure, they found that people on beta-blockers generally burned fewer calories and fat after a meal -- measured by a device called a calorimeter.

The patients on beta blockers also reported lower physical activity levels in their day-to-day lives. (Beta blockers are suspected of curbing people’s physical activity because the drugs slow the heart rate and may cause people to tire more easily.)

Together, the findings suggest that beta blockers lead to weight gain by curbing people’s calorie expenditure, according to the researchers, led by Dr. Paul Lee of St. Vincent’s Hospital in Sydney.

In today’s society, where obesity is a general public-health issue, that weight gain is particularly concerning, according to Lee.

“Our hypothesis is that widespread use of beta blockers may fuel the modern-day obesity epidemic,” he told Reuters Health in an email.

So what should you do if you’re on a beta blocker?

Just what people not on the drugs should do, Lee said. “Lifestyle modification is always the first step: a good balanced diet and regular exercise,” he noted.

That said, exercise and calorie burning may be more difficult for people on a beta blocker. So beta blocker users who are worried about weight gain may want to ask their doctor if they could use a different type of blood-pressure medication -- or one of the newer beta blockers that seem to have less risk of weight gain, Lee said.

He stressed, though, that beta-blockers are often an important drug for people with heart disease, and patients should not simply stop using them because of weight worries.

Instead, Lee said, they may need to be “extra mindful” of their weight, and get additional help -- like referral to a dietitian -- if needed.

The findings are based on data from 11,438 adults; most were patients in a clinical trial looking at the effects of blood pressure lowering among people with diabetes. The rest were patients being treated for diabetes or high blood pressure at St. Vincent’s.

On average, Lee’s team found, patients on beta blockers were anywhere from 11 to 37 pounds heavier, depending on the study group.

In the smaller study of patients with high blood pressure, the researchers compared calorie- and fat-burning in 11 people on beta blockers and 19 adults the same age and weight who were not on the drugs.

They found that after a meal, the beta blockers users burned roughly 30 to 50 percent fewer calories and fat.

The findings do not prove that beta blockers were the reason for the excess weight or lower calorie-burning. But they are in line with what’s known about the medications’ effects on the nervous system and weight.

Lee noted that beta blockers are no longer the first choice drugs for high blood pressure. So for people who do not need the drugs to manage heart disease, another blood pressure medication might be more appropriate anyway.

Other types of blood pressure drugs include ACE inhibitors, calcium channel blockers and diuretics (water pills). Many of these, as well as the beta blockers, are available in generic forms for as low as $20 per month or less.

SOURCE: International Journal of Obesity, online February 8, 2011.