What is HMPA?

HMPA at a glance

Where does HMPA come from?

HMPA turns up in two places. The first is fermented rice bran, which is where manufacturers source it (Suntory FAQ). The second is your own gut. When you eat grains, you take in ferulic acid (chemists call it HMCA, 4-hydroxy-3-methoxycinnamic acid). Gut bacteria convert some of it into HMPA.

That second route is what got researchers interested. A 2019 study in diet-induced obese mice found that the metabolic benefits of eating HMCA were largely down to the HMPA that gut microbes made from it (Nutrients, 2019).

1. Diet: you eat grains that contain ferulic acid (HMCA).
2. Gut: microbes convert HMCA into HMPA.
3. Receptor: HMPA activates GPR41, a receptor that senses gut-microbe metabolites.
4. Effect (in mice): fat breakdown in the liver goes up and diet-induced weight gain goes down.

How does HMPA work?

The best-described mechanism runs through GPR41 (free fatty acid receptor 3, or FFAR3). In a 2023 study, mice on a high-fat diet that were given HMPA gained less weight and had less fat in the liver, because HMPA switched on lipid catabolism (the body's fat-burning pathway) via GPR41. The researchers also tested mice that lack GPR41 to show that the effect depends on the receptor (Scientific Reports, 2023).

What does the research show?

Three peer-reviewed papers and one company-reported human study make up the evidence that HMPA products cite today:

• Metabolism (mice, 2019): HMPA from gut microbes improved the metabolic condition of obese mice.
• Liver fat and GPR41 (mice, 2023): HMPA reduced diet-induced weight gain and liver fat through GPR41.
• Muscle (mice, 2024): 14 days of HMPA improved grip strength. Endurance didn't change (IJMS, 2024).
• Visceral fat (humans, company-reported): 74 Japanese adults with a BMI of 23–30 taking 23 mg a day for 12 weeks had 4.2 cm² less visceral fat area than non-takers (ReFa).

adults in the only human study

74

HMPA per day in that study

23 mg

study length

12 wk

visceral fat area vs non-takers (company-reported)

−4.2 cm²

For the fat-loss question specifically, read Does HMPA help with fat loss?.

HMPA vs ferulic acid

HMPA and ferulic acid are close chemical relatives. HMPA is ferulic acid with one double bond reduced, which is why it's also called dihydroferulic acid.

Is HMPA safe?

HMPA occurs naturally in fermented food and your gut makes it every day from ordinary grains. In Japan it's sold in Suntory's Tokusui as a Food with Function Claims product, a category where the company files the safety and function evidence and the state doesn't evaluate it.

We haven't found published long-term safety studies in people. New ingredients in India go through FSSAI's approval process for non-specified foods, and we'll publish our regulatory status on this site before Get Waisted goes on sale.

Where can you get HMPA?

• Japan: Suntory Tokusui, a 600 mL HMPA water with 23 mg per bottle, launched 21 October 2025.
• Japan: ReFa Slim Up Vinegar, a drinking vinegar that cites the same 12-week study.
• India: Get Waisted HMPA Water, a 330 mL can with a lab report for every batch. Batch 001 is in testing; join the list.