The "fat vaccine" is under investigation by Cytos, a Swiss biotechnology company. Currently called CYT009-GhrQb, the vaccine's purpose is to create an immune response in the body against ghrelin, a peptide (a short chain of amino acids, the building blocks of proteins) released by cells in the stomach. Scientists don't know exactly how ghrelin works, but several studies have shown that it stimulates appetite. In one study of anorexic patients, people given ghrelin were hungrier and ate more than those given a placebo. Blood levels of ghrelin quickly rise after people lose weight, which may be why so many people have trouble keeping the weight off. Studies have also indicated that bariatric surgery works, in part, because ghrelin levels drop when the stomach has been reduced.
The CYT009-GhrQb vaccine instructs the immune system to release antibodies that attach to ghrelin and hold it in the bloodstream. This keeps the peptide from making its way into the brain and triggering the feeling of hunger.
But will the vaccine actually cause people to lose weight?