Novel oral compound TOFA boosts energy burn, offering potential complement to GLP-1 obesity drugs

Researchers at UC Berkeley have identified a small molecule that attacks obesity from an entirely different angle than the drugs now dominating weight-loss medicine. Instead of making people feel full, this compound—called TOFA—makes their bodies burn more calories. In mice fed a high-fat diet, the treatment produced an 18 percent reduction in body weight while leaving muscle mass untouched, a result that suggests a fundamentally different approach to the obesity problem.

The distinction matters because it points to a gap in how current therapies work. Semaglutide and tirzepatide, the GLP-1 drugs that have reshaped obesity treatment over the past few years, work primarily by suppressing appetite. They tell the brain to eat less. TOFA does something else entirely: it increases the rate at which the body converts food into heat and motion. In metabolic-cage experiments, the compound boosted energy expenditure by roughly 18 percent, whether mice were kept at room temperature or in warmer conditions. The weight loss was not driven by increased activity or by the body's failure to absorb nutrients. Instead, the mice were simply burning more fat.

The mechanism behind TOFA's effect involves two distinct metabolic actions working in concert within a single molecule. The compound inhibits enzymes called acetyl-CoA carboxylases 1 and 2, which normally direct the body toward storing energy as fat. At the same time, it partially activates two nuclear receptors—PPARα and PPARδ—that govern how the body handles and expends lipids. This dual action appears to be what gives TOFA its edge. When researchers tested compounds that targeted only one of these pathways, they did not achieve the same metabolic improvements. The combination, the Berkeley team found, produced benefits that neither pathway alone could deliver.

What makes the finding potentially significant is not just that TOFA works, but how it might work alongside existing drugs. When the researchers combined TOFA with semaglutide or tirzepatide in obese mice, the weight loss was substantially greater than either drug produced on its own. More importantly, the additional weight shed came almost entirely from fat, not muscle. The combination also produced sharper improvements in blood sugar control, insulin levels, and the fatty substances circulating in the bloodstream and accumulating in the liver. This suggests a practical advantage: if TOFA can amplify the effects of GLP-1 drugs while preserving muscle, it might allow doctors to use lower doses of the incretin medications, potentially reducing side effects and the need for frequent injections.

The Berkeley team also tested TOFA in mouse models of metabolic dysfunction-associated steatotic liver disease, a condition in which fat builds up in the liver and can progress to inflammation and scarring. The compound reduced fat accumulation, lowered markers of inflammation, and decreased signs of fibrosis. These results hint at benefits beyond weight loss itself, though they remain confined to animal studies.

All of this is still preclinical work. No human has taken TOFA. The leap from mouse metabolism to human metabolism is substantial, and compounds that work in rodents frequently fail in people or produce unexpected effects. But the research points toward a conceptual shift in how obesity might be treated. Rather than asking how to make people eat less, it asks how to make their bodies burn more. The two approaches are not mutually exclusive. If they can be combined safely and effectively, they might offer a more complete solution to a problem that current drugs, for all their power, have not fully solved.