Written By Michael Greger M.D. FACLM on January 8th, 2019

Vinegar has evidently been used as a weight-loss aid for nearly 200 years. Like hot sauce, it can be a nearly calorie-free way to flavor foods, and all sorts of delicious exotic vinegars—like fig, peach, and pomegranate—are available to choose from. The question, though, is whether there is something special about vinegar that helps with weight loss, which is the topic of my video Does Apple Cider Vinegar Help with Weight Loss?.

Vinegar is defined as simply a dilute solution of acetic acid, which takes energy for our body to metabolize, activating an enzyme called AMPK that is like our body’s fuel gauge. If it senses that we’re low, it amps up energy production and tells the body to stop storing fat and start burning fat. And, so, given our obesity epidemic, “it is crucial that oral compounds with high bioavailability are developed to safely induce chronic AMPK activation,” which would be potentially beneficial for long-term weight loss. There’s no need to develop such a compound, though, if you can buy it in any grocery store.

We know vinegar can activate AMPK in human cells, but is the dose one might get when sprinkling it on a salad enough? If you take endothelial cells (the cells lining our blood vessels) from umbilical cords after babies are born and expose them to various levels of acetate, which is what the acetic acid in vinegar turns into in our stomach, it appears to take a concentration of at least 100 to really get a significant boost in AMPK. So, how much acetate do you get in your bloodstream sprinkling about a tablespoon of vinegar on your salad? You do hit 100, but only for about 15 minutes, and even at that concentration, 10 or 20 minutes exposure doesn’t seem to do much. Now granted, this is determined in a petri dish. What do clinical studies show us?

A double-blind trial was conducted investigating the effects of vinegar intake on the reduction of body fat in overweight men and women. The researchers call them obese, but they were actually slimmer than the average American. In Japan, they call anything over a BMI of 25 obese, whereas the BMI of the average American adult is about 28.6. Nevertheless, they took about 150 overweight individuals and randomly split them into one of three groups: a high-dose vinegar group drinking a beverage containing two tablespoons of apple cider vinegar a day, a low-dose group drinking a beverage containing only one tablespoon of apple cider vinegar a day, and a placebo control group drinking an acidic beverage they developed to taste the same as the vinegar drink but using a different kind of acid so, there was no acetic acid.

There were no other changes in their diet or exercise. In fact, the researchers monitored their diets and gave them all pedometers so they could make sure the only significant difference amongst the three groups was the amount of vinegar they were getting every day. Within just one month, there were statistically significant drops in weight in both vinegar groups compared with placebo, with the high-dose group doing better than the low-dose group, and the weight loss just got better month after month. In fact, by month three, the do-nothing placebo group actually gained weight, as overweight people tend to do, whereas the vinegar groups significantly dropped their weight. Was the weight loss actually significant or just statistically significant? Compared with the placebo group, the two-tablespoons-of-vinegar-a-day group dropped five pounds by the end of the 12 weeks. That may not sound like a lot, but they got that for just pennies a day without removing anything from their diet.

They also got slimmer, losing up to nearly an inch off their waist, suggesting they were losing abdominal fat. The researchers went the extra mile and put it to the test. They put the research subjects through abdominal CT scans to actually measure directly the amount of fat in their bodies before and after. They measured the amount of superficial fat, visceral fat, and total body fat. Superficial fat is the fat under your skin that makes for flabby arms and contributes to cellulite. Visceral fat, on the other hand, is the killer. It’s the fat that builds up around your internal organs that bulges out the belly—and the kind of fat the placebo group was putting on when they were gaining weight. Both the low-dose and high-dose vinegar groups, however, were able to remove about a square inch of visceral fat off that CT scan slice.

Like any weight loss strategy, it only works if you do it. A month after they stopped the vinegar, the weight crept right back, but that’s just additional evidence that the vinegar was working. But how was it working?

A group of researchers in the United Kingdom suggested an explanation: Vinegar beverages are gross. They created vinegar beverages that were so unpleasant the study subjects actually felt nauseated after drinking them and ate less of the meal the researchers provided. So, there you go: Maybe vinegar helps with both appetite control and food intake, though these effects are largely due to the fruity vinegar concoctions invoking feelings of nausea. Is that what was going on in the original study? Were the vinegar groups just eating less? No, the vinegar groups were eating about the same compared with placebo. Same diet, more weight loss––thanks, perhaps, to the acetic acid’s impact on AMPK.

Now, the CT scans make this a very expensive study, so I was not surprised it was funded by a company that sells vinegars, which is good, since we otherwise wouldn’t have these amazing data, but is also bad because it always leaves you wondering whether the funding source somehow manipulated the results. The nice thing about companies funding studies about healthy foods, though, whether it’s some kiwifruit company or the National Watermelon Promotion Board (check out watermelon.org), is, really, what’s the worst that can happen? Here, for example, even if the findings turned out to be bogus and worst comes to worst, your salad would just be tastier.

I’m so excited to finally be getting to this topic. Type “vinegar” into PubMed, the search engine biomedical literature, and 40,000 studies pop up. It took me a while to take it all in, but I’m so glad I did, as it’s something that has caused a shift in my own diet. I now try to add various vinegars every day.