Their study of 27,000 men, in the journal Circulation, showed those skipping breakfast were at a greater risk of heart problems. The team at the Harvard School of Public Health said missing the meal put an "extra strain" on the body.
The British Heart Foundation said breakfast helped people resist sugary snacks before lunch. The men, aged 45-82, were studied for 16 years. During that time there were more than 1,500 heart attacks or cases of fatal heart failure.
However, people who skipped breakfast were 27% more likely to have heart problems than those who started the day with a meal. The researchers adjusted for other lifestyle risk factors such as smoking and exercise.
Researcher, Dr Leah Cahill told the BBC: "The take-home message is eat in the morning when you wake up, preferably within an hour.
"The results show that something is better than nothing, but it's always better to have something healthy and balanced."