Appetite-suppressing drug burns fat, too

An experimental drug seems to assail obesity through dual biological actions, according to a new study. Already known to reduce animals’ inclination to overeat, a drug called C75 appears to further contribute to weight loss by promoting metabolism in tissues that store fat.

To investigate the metabolic effects of C75, Francis P. Kuhajda and his colleagues at Johns Hopkins Medical Institutions in Baltimore, placed two groups of overfed, obese laboratory mice on identical diets. One group also received C75. These mice burned more calories and lost weight more rapidly than did their counterparts, the researchers report in an upcoming issue of the Proceedings of the National Academy of Sciences.

In subsequent experiments, the researchers found that exposing fat-storing cells from mice and fat-metabolizing liver cells from rats to C75 caused the cells to accelerate their metabolism of fat. This occurs because the drug revs up an enzyme, called o-carnitine palmitoyltransferase-1 (CPT-1), that helps convert fat into energy.

When an organism is eating excess food, the body steps up production of a second substance that usually inhibits CPT-1 and thus slows fat metabolism. The researchers say C75 seems to biochemically trump this inhibitory substance, however, which leaves CPT-1 free to reduce stored fat in the animals regardless of food intake.