New research suggests that people who skip breakfast have high dopamine levels, which can lead to overeating and eventual weight gain.

Researchers from the University of Missouri found that eating breakfast, particularly meals rich in protein, increases young adults' levels of a brain chemical associated with feelings or reward, which may reduce food cravings and overeating later in the day.

"Our research showed that people experience a dramatic decline in cravings for sweet foods when they eat breakfast," Heather Leidy, an assistant professor of nutrition and exercise physiology, said in a statement. "However, breakfasts that are high in protein also reduced cravings for savory -- or high-fat -- foods. On the other hand, if breakfast is skipped, these cravings continue to rise throughout the day."

For the study, Leidy examined the effects of different breakfasts on participants' levels of dopamine, a brain chemical involved in moderating impulses and reward, including food cravings. Dopamine levels were determined by measuring homovanillic acid (HVA), the main dopamine metabolite. Eating initiates a release of dopamine, which stimulates feelings of food reward. The reward response is an important part of eating because it helps to regulate food intake.

"Dopamine levels are blunted in individuals who are overweight or obese, which means that it takes much more stimulation -- or food -- to elicit feelings of reward; we saw similar responses within breakfast-skippers," Leidy said. "To counteract the tendencies to overeat and to prevent weight gain that occurs as a result of overeating, we tried to identify dietary behaviors that provide these feelings of reward while reducing cravings for high-fat foods. Eating breakfast, particularly a breakfast high in protein, seems to do that."

In the United States, people are skipping breakfast more frequently.

"It used to be that nearly 100 percent of American adults, kids and teens were eating breakfast, but over the last 50 years, we have seen a decrease in eating frequency and an increase in obesity," Leidy added.

The findings were published in the Nutrition Journal.