They've worked out that you're much more likely to catch a cold or even the flu if you set out for school before snacking on cereal.
A lack of breakfast is just one thing that scientists say can make it easier for bugs like colds and flu to find a victim.
They discovered that the people who suffered from more than one disease during the research, were those who didn't eat breakfast as often.
In their tests of 188 people they also found that stress, smoking and drinking alcohol can make things worse.
Hear story
Vote: Do you eat breakfast?
