Weight loss is about 12 to 13 pounds after a year in patients taking orlistat compared to the control group's loss of about 6 pounds. The drug would not be expected to help someone on a very low fat diet, like the McDougall diet, lose weight because there is so little fat to digest in the first place. Side effects are mostly limited to the gastrointestinal tract and due to the drug's intended effect, which is the malabsorption of dietary fat. The more fat consumed, the greater the adverse events. Another important means by which orlistat causes weight loss is by behavior modification.
People eat less fat in order to avoid the diarrhea and fatty stools.
The type of antibodies detected, IgA, are a sign of current infection with the bacteria. Those with detectable antibodies had about twice the risk of fatal heart disease compared with those people without detectable antibodies. Over more than 13 years of follow up, six extra deaths occurred among 100 men with elevated IgA antibodies at the beginning of the study. Since then the bacteria has been cultured out of atherosclerotic plaques, especially in vessels in the heart. Local infection may be involved in the formation of the plaques and it may also increase the tendency for the blood to clot, leading to a heart attack.