A study of 21,094 US male doctors for two decades found that being even slightly overweight increased the risk of developing heart disease. The study, reported on by Reuters and published in the journal Circulation, focused on individuals with a BMI between 25 and 29.9 (defined as "overweight")

For every seven pounds of extra weight on a man of average height (5 ft 10), the risk of heart failure rose by 11 percent over the course of the study.

Although it's long been known that obesity (a BMI over 30) is a risk factor for heart disease, this research indicates that being even 10 or 20 lbs overweight increases the likelihood of heart problems.

The good news, though, is that a small amount of exercise can vastly cut the risk of heart disease. Dr. Satish Kenchaiah, who led the study, told Reuters that:

As far as vigorous physical activity is concerned, even if somebody said they exercised one to three times per month -- which is a very low level of exercise -- they had an 18 percent reduction in the risk of heart failure after accounting for all other established risk factors.

So if you are overweight, just losing a few pounds and going for a jog or a gym class every week could help protect your heart.