A meal higher in fiber boosts feelings of fullness in women and increases levels of a hormone linked with satiety, according to researchers at the University of California - Davis.

Previous research has shown that cholecystokinin, a hormone released from the small intestine when a fat-containing food is eaten, may be the chemical messenger that responds to fat, telling the brain that the body is getting full. Researchers now believe that fiber can trigger the same signals as fat.

Researchers conducted a study to test how levels of cholecystokinin respond to increases in dietary fat and fiber and how that hormonal response relates to feelings of fullness.

A test group of men and women were fed three different breakfast meals that were low-fiber, low fat; high fiber, low fat; or low fiber, high fat.

Blood samples were taken during and after the meals were eaten to measure hormone levels. The release of cholecystokinin was linked to feelings of fullness reported by the study participants.

Investigators found that in women, both high-fat and high-fiber meals were linked with greater feelings of fullness and significantly higher levels of cholecystokinin than the low-fat, low-fiber meals.

In men, the low-fat, low-fiber and low-fat, high-fiber meals caused greater feelings of fullness and there was not a significant different in the hormonal increase between the various meals.

"These results indicate that the addition of fiber to a meal can increase a person's feeling of being full," said Barbara Schneeman, nutrition professor and study leader. "It appears this is due not only to fiber creating a greater volume of food in the gastrointestinal tract, but also to fiber promoting the release of cholecystokinin."

Further research is needed to help understand the long-term effects of fiber on controlling food consumption and energy balance, and to determine the role that gender plays in the mechanisms that control food intake, she added.

Other sources: University of California - Davis