A 1970s Compound Made Obese Mice Burn Up to 18 Percent More Energy, Without Losing Muscle
Every drug that has reshaped weight loss in the last few years, semaglutide, tirzepatide, orforglipron, pulls one lever. Eat less. Readers ask me constantly what that lever costs, and the honest answer is that eating less tends to take some muscle with the fat. A team at UC Berkeley just published research on a compound that pulls a different lever entirely, and I think it deserves more attention than the mouse study headline suggests.
- UC Berkeley researchers published a compound called TOFA that made obese mice burn up to 18 percent more energy, with no change in how much they ate, how much they moved, or their body temperature.
- The mice lost fat without losing meaningful muscle, and their blood sugar, insulin sensitivity, and fatty liver all improved at the same time.
- TOFA blocks the enzymes that build fat while also switching on the genes that burn it, and combined with semaglutide or tirzepatide it worked better than either drug alone.
- This is mouse research only, the senior author and first author hold equity in the startup licensing the compound, and there is no human data and nothing you can buy.
What UC Berkeley actually found
Characterizing a compound like TOFA, and testing it against dozens of conditions at once, starts with exactly this kind of bench work.
Linda Bartlett (Photographer)
Illustrative: a National Cancer Institute photograph of unrelated antibody research, not a photograph from the UC Berkeley TOFA study or its researchers.
The compound is called TOFA, short for a name few people outside a chemistry department could pronounce. It was first discovered in the 1970s as a drug that blocks an enzyme called ACC, which cells use to build fat. Several ACC blocking drugs made it partway through human testing over the decades and every one of them failed, because blocking that enzyme also raises triglycerides, a real cardiovascular risk. TOFA turns out to do something the earlier drugs did not. Alongside blocking ACC, it also partially switches on two genetic receptors, PPAR alpha and PPAR delta, that tell cells to take up fat and burn it for fuel. In obese mice, that combination raised energy expenditure by up to 18 percent, with no rise in activity or body temperature to explain it away. The mice lost fat. They did not lose meaningful muscle. Insulin sensitivity improved, triglycerides went down instead of up, and signs of fatty liver disease improved too. When the Berkeley team combined TOFA with semaglutide or tirzepatide, the mice did better on weight, blood sugar, and triglycerides than with either drug by itself.
Food intake
No change in how much the mice ate.
Physical activity
No change in how much the mice moved.
Body temperature
No rise, meaning this is not simple thermogenesis.
The up to 18 percent rise in energy expenditure this compound produced in obese mice showed up without moving any of the three numbers that would normally have to change first.
Why the muscle question matters so much right now
Losing muscle while losing fat is the single most common worry I hear from readers on a GLP-1 drug, and an entire industry of protein powders and creatine has grown up around answering it after the fact. What makes TOFA interesting is that it is not a fix bolted onto an appetite suppressant. It is a completely different mechanism, one that never asks the body to eat less in the first place, so there is no forced calorie deficit pulling muscle down along with fat. That is a structurally different answer to the muscle loss question, not a better version of the same one, and it is the reason a 1970s compound with a new mechanism is worth writing about even though it is nowhere near a pharmacy shelf.
Honest caveat
Every result here is in mice, and the researchers themselves say safety and effectiveness in humans have not been tested. The senior author, the first author, and one co author are founders or equity holders in the startup that has licensed this compound, which does not make the findings false but does make the framing an interested one. ACC blocking drugs have a real history of failing in human trials, and the claim that TOFA avoids the old triglyceride problem is exactly the claim earlier candidates needed and never delivered on in people. One trade outlet reported this as an 18 percent reduction in body weight, which is wrong. The 18 percent figure is energy burned, not weight lost, and that distinction matters. Realistically this is the better part of a decade from any human product, if it arrives at all, and there is no consumer version. Anything sold today under the name TOFA is not this compound.
a completely different mechanism, one that never asks the body to eat less in the first place
What this means for you
If you are on a GLP-1 drug or thinking about one, TOFA is not something you can act on today, and I want to be direct about that rather than let a promising mouse study imply otherwise. What it does tell you is where the research is actually heading, toward mechanisms that raise how much energy your body burns rather than only lowering how much you eat, which is the direction that would finally separate fat loss from muscle loss at the mechanism level instead of trying to protect muscle after the fact with protein and resistance training. For now, the tools that actually help preserve muscle on a GLP-1 drug remain the boring ones, adequate protein intake and resistance training, and no supplement on the market has been shown to prevent the lean mass loss that comes with these drugs. Watch this compound the way you would watch an early stage biotech story, with real interest and zero expectation of using it soon.
Primary sources
- Lee JY, Zhu C, Boldridge MA, et al. "A multi-functional oral small molecule targeting energy and lipid metabolism to treat obesity and related metabolic disorders." Science Advances, published online August 21, 2026.
- Kara Manke, "A promising new weight loss and diabetes treatment helps burn fat while keeping muscle," UC Berkeley News, August 21, 2026.
Common questions
Can I get TOFA or take it for weight loss right now?
No. TOFA has never been tested in a single human being, has no approved formulation, and is not sold anywhere. If you see anything marketed under that name, treat it as a red flag rather than an early access opportunity. This compound is, optimistically, close to a decade away from any human product.
Is the 18 percent figure a weight loss number?
No, and this is worth being precise about because it has already been reported wrong once. The 18 percent refers to how much more energy the mice burned, measured directly, not how much weight they lost. Those are two different numbers, and this brief only reports the energy figure because that is what the UC Berkeley release itself states.
Should this change how I think about protecting muscle on semaglutide or tirzepatide?
Not yet, practically speaking. TOFA is a research finding in mice, not an available treatment, so it does not change what you can actually do today. What you can control right now is protein intake and resistance training, and it remains true that no supplement has been shown to prevent GLP-1 associated muscle loss. TOFA is worth watching as a sign of where the science is heading, not as something to plan around.
Stay Curious.
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