Breakfast is often hyped as the most important meal of the day, but it seems that your all-in-one sandwich is not doing you any favors. Researchers discovered that eating fast-food breakfast sandwiches may have near-immediate effects on your blood vessels.

The study, done by the University of Calgary’s Libin Cardiovascular Institute of Alberta, is still in its beginning stages, but it examines “what happens in the blood vessels after someone eats a high-fat, high-salt meal.”

A group of 20 young people (average age: 23) was broken into two groups. One fasted while the other was given tests in which the blood vessels on the members’ forearms were examined for blood-flow efficiency right after they ate two fast-food breakfast sandwiches.

The latter group experienced “a decrease in the ability of the small vessels of the forearm to dilate and generate blood flow,” according to Dr. Todd Anderson, director of the┬áLibin Cardiovascular Institute. This can mean a higher risk of heart attack and stroke.

[via U.S. News and World Report]