Say this first, before anything else. This is a mouse study. The compound has never been given to a person in any published research, nobody knows if it's safe in humans, and it isn't sold anywhere, not as a research peptide, not as anything. Nothing below is a suggestion that you could get or use this right now. What it is, is new peer-reviewed evidence on a question a lot of our readers already have about their own routines, whether pairing something with a GLP-1 can protect muscle while the weight comes off.
What happened
Researchers at UC Berkeley, led by professor Anders Naar, published a study on August 21 in the journal Science Advances describing a molecule called TOFA (5-tetradecyloxy-2-furoic acid) that increased fat burning in obese mice without the muscle loss that comes with GLP-1 medications like semaglutide and tirzepatide. When the researchers combined TOFA with those same GLP-1 drugs, the pairing worked better than either one alone.
TOFA isn't new. It was first discovered in the 1970s as part of a class of compounds called ACC inhibitors, which block an enzyme involved in making cholesterol and triglycerides. Several older ACC inhibitors made it partway through human trials for metabolic disease decades ago and were dropped, mostly because they tended to raise triglycerides, which is a real problem for heart health. What's new is what the Berkeley team found TOFA is also doing.
Why this one didn't raise triglycerides like the earlier ones
Body weight comes down through one of two doors, eating less or burning more. GLP-1 medications work almost entirely through the first door, they lower how much food you take in. TOFA appears to work through the second one. The researchers found it doesn't just block lipid production the way older ACC inhibitors did, it also switches on two cellular receptors, PPAR-alpha and PPAR-delta, that tell cells to take up fat and burn it for fuel. That second piece looks like the reason TOFA raised energy use in mice by as much as 18%, with no change in how active the mice were, and didn't push triglycerides up the way its chemical predecessors did.
What the mice actually showed
In obese mice, TOFA improved insulin sensitivity, blood sugar control, triglycerides, and markers of fatty liver disease. The mice lost body fat without a meaningful drop in lean muscle mass. That muscle-sparing result held on its own, without any GLP-1 in the picture at all.
The part most relevant to anyone already combining peptides with a GLP-1 medication is what happened when the researchers added TOFA on top of semaglutide or tirzepatide. The combination produced bigger improvements in body weight, blood sugar, insulin, and triglycerides than either compound alone. Naar's framing, in the university's own announcement, was that GLP-1s and TOFA pull different levers, appetite versus energy burn, and worked additively together rather than one substituting for the other.
Worth knowing plainly: three of the paper's researchers, including Naar and first author Justin Lee, have started a company called ReRx Therapeutics to develop TOFA further, using UC Berkeley intellectual property the company has licensed. They disclosed this themselves in the study. It's a real financial interest, and it doesn't make the mouse data wrong, but it's worth knowing when you read anyone's framing of the finding, including the university's own.
What this means for you right now
If you're researching peptides to pair with a GLP-1 specifically to protect lean mass, a real and common reason people in this space combine compounds, this study doesn't hand you a new tool. TOFA isn't available to buy, isn't a research peptide, and won't be for years if it ever clears human safety testing at all. What it does hand you is independent, peer-reviewed support for the underlying idea a lot of current combinations are built around, that pairing a GLP-1 with something working on energy expenditure rather than appetite is worth being curious about. That's a different claim than "this specific compound works," and it's worth keeping the two separate.
If you're weighing your own current combination and want to see what people are actually pairing with semaglutide or tirzepatide today, along with current per-mg pricing across vendors, our guide to fat loss and body composition combinations and the live price comparison tool cover what's real and buyable right now.
What to watch next
The obvious next question is whether TOFA, or anything working the same way, ever gets tested in a person. That's a years-long road in the best case, and mouse metabolic results often don't carry over cleanly to humans. We'll cover it if and when human data appears, since that's the point where this stops being a curiosity and starts being something worth a second look.
Sources
- 1. A Promising New Weight Loss and Diabetes Treatment Helps Burn Fat While Keeping Muscle, Berkeley News, August 21, 2026.
- 2. Experimental Compound Helps Burn Fat Without Muscle Loss, ScienceDaily, August 23, 2026.
- 3. Näär A, Lee JY, et al., Science Advances study, Science Advances, August 21, 2026, doi: 10.1126/sciadv.aed3119.