Do you always seem to feel hungry? Are your hunger cravings out-of-control? Your desire to eat may have more to do with your intestinal bacteria than previously thought, according to a study published last week in Science magazine.
Researchers at Emory University School of Medicine have found that intestinal bacteria can affect appetite and metabolism, leading to excess caloric consumption, obesity, elevated blood sugar, and insulin resistance. The findings, together with previous research which showed that differences exist in intestinal bacteria between obese and lean individuals, suggests that the digestive tract contributes to obesity and metabolic disease.
At birth, our digestive tract is sterile, but it is quickly bombarded with bacteria from first foods, family members, and the environment. Most of the bacteria population that develops within our intestines is necessary and beneficial to health, remaining relatively stable throughout life. Unhealthy imbalances may occur, however, due to diet, antibiotics, and lifestyle changes.
For the study, researchers observed mice with normal and altered immune systems. The mice with altered immune systems due to different bacteria growing in their intestines, ate more than regular mice and were heavier, had elevated triglycerides, cholesterol, and blood pressure as well as mildly elevated blood sugar and increased production of insulin.
The research suggests that metabolic syndrome may be “inherited” from the environment rather than genetically. To test the theory, bacteria from fat mice were injected into the germ-free intestines of normal newborn mice. The mice began eating more and developed many of the characteristics of metabolic syndrome. When placed on a restricted diet, they did not gain weight but still experienced the other symptoms.
According to senior author Andrew Gewirtz, PhD, associate professor of pathology and laboratory medicine at Emory University School of Medicine, “People are getting obese because they’re eating more, but it suggests the reason they’re eating more may not simply be that calories are cheap and available. The reason they’re eating more may be an increased appetite resulting from changes in intestinal bacteria.” He says his next step is to study how intestinal bacteria changes in people having weight loss surgery.
Source: “Intestinal bacteria drive obesity and metabolic disease in immune-altered mice,” Emory University Press Release, March 4, 2010