Physicians have long warned patients against gaining significant weight, telling them that too much could cause cardiovascular disease. But new research shows that even a little weight, as little as 5 percent, could make a difference in one’s heart health.

The study, published in the Journal of the American Heart Association, included more than 1,200 patients. Researchers assessed them at the beginning of the study, when none of them had heart disease, and then again after seven years.

Results showed that patients who gained as little as 5 percent more weight were more likely to have thickening and enlargement of their left ventricle and slower heart function.

“Any weight gain may lead to detrimental changes in the heart above and beyond the effects of baseline weight so that prevention should focus on weight loss,” said Ian Neeland, MD, the study’s lead author and a cardiologist and assistant professor of medicine at UT Southwestern Medical Center in Dallas, in a statement. “If meaningful weight loss cannot be achieved, the focus should be on weight stability.”

Though the findings are startling, the researchers say they don’t necessarily mean that everyone who gains weight will develop heart failure. However, weight fluctuation will likely affect the heart muscle.

Additional research is needed to exactly explain the links between weight management and heart disease.