Part of the viral olive oil claim is real and part of it is not. Real: fresh extra virgin olive oil contains oleocanthal, which research shows acts on the same inflammation enzymes as ibuprofen, and there is human evidence linking high-polyphenol olive oil to smaller waist circumference. Not established: the popular story that olive oil lowers cortisol and that this releases belly fat. No human evidence was found for that step. The buying advice going around is sound though, and it matters more than most people think.
A video is doing the rounds claiming that two to four tablespoons of olive oil a day lowers cortisol and melts belly fat. Several people have sent it to me. The interesting thing is that it cites real research, from genuinely prestigious journals, and then draws a conclusion those papers do not support.
So let us separate the parts. This matters beyond olive oil, because the pattern is everywhere: real citation, real mechanism, and then one unsupported leap at the end where the promise lives.
What is actually true
The ibuprofen finding is real
In 2005, a researcher at the Monell Chemical Senses Center noticed that fresh olive oil in Italy produced the same peppery sting at the back of his throat as liquid ibuprofen. That observation turned into a paper in Nature.
The compound is called oleocanthal, and the finding held up: it inhibits COX-1 and COX-2, the same enzymes ibuprofen acts on (Beauchamp et al., 2005, Nature).
Keep it in proportion. A tablespoon of olive oil delivers far less than a therapeutic dose of ibuprofen. This is a reason to care about the quality of the fat in your meals. It is not a reason to treat olive oil as medication, and it is not a painkiller substitute.
The heart study is real, with a caveat the videos leave out
The large trial people cite is PREDIMED, which followed around 7,400 higher-risk adults and reported fewer major cardiovascular events in the group adding extra virgin olive oil compared with a low-fat control diet.
Here is the part that gets dropped. The original 2013 paper was retracted. Randomization had not been carried out properly for roughly a fifth of participants, about 1,588 people. The authors re-analysed the data using methods that do not assume everyone was properly randomized, and republished in the New England Journal of Medicine in June 2018. The effect estimates barely moved.
So the finding survived, and that is genuinely reassuring. But it should be described as an association rather than a clean causal result, and the paper worth citing is the 2018 republication (Estruch et al., 2018, NEJM). Anyone still citing the 2013 version is citing a retracted article.
There is direct evidence on waist size, and nobody mentions it
This is the odd part. The strongest evidence for the actual claim being made is the evidence the videos skip.
In a two-month study, daily extra virgin olive oil high in oleocanthal was associated with reduced body weight, waist circumference and inflammatory markers in people with metabolic syndrome (Fabiani et al., 2020, Nutrients). A randomised crossover trial has also tested high-oleocanthal olive oil in people with obesity and prediabetes.
These are small, short studies in specific groups, so they support a hedged association rather than a promise. But they measure an outcome people care about, which makes them more useful than any proposed mechanism.
What is not established
The cortisol chain. The claim runs: oleocanthal lowers inflammation, lower inflammation lowers cortisol, and lower cortisol releases stored belly fat. Each link sounds reasonable. But I could not find human evidence connecting olive oil or oleocanthal to reduced cortisol, or to fat loss happening through a cortisol pathway.
That step is the whole argument, and it is the one with nothing under it.
Notice that the waist circumference evidence above does not rescue it. An association with an outcome is not confirmation of a mechanism. The studies did not measure cortisol, so they cannot tell you why the change happened.
The advice that follows from it, taking two to four tablespoons daily to signal your body to release midsection weight, is not supported. Olive oil is also energy dense, so adding four tablespoons on top of everything else is a decision worth making deliberately rather than by accident. The trials that showed benefit had people replace other fats, not add on top of them.
The buying advice is the useful part
Here the videos are right, and it matters more than the mechanism debate. Oleocanthal is fragile. Most supermarket olive oil has very little left by the time it reaches you.
- Skip anything labelled "light" or "pure" olive oil. Those are refined, which strips the polyphenols this whole discussion is about.
- Dark bottle, always. Light degrades the active compounds. A clear bottle under supermarket lights for months is a poor bet before you even open it.
- Look for a harvest date, not a best-before date. Polyphenol content is highest in the first year after harvest. No harvest date means you cannot tell.
- "Cold-pressed extra virgin" on the label, not just "extra virgin".
- Taste it. Swallow a small amount neat. A fresh, high-polyphenol oil produces a distinct peppery catch at the back of the throat. That sting tracks the oleocanthal. If it tastes like nothing, there is not much left in it.
That last test is the most practical thing in this article. It costs nothing and it tells you more than the label does.
Where olive oil actually fits
In the Insulin Fix framework, olive oil sits in Hack 5, healthy fats. The reason is simpler than the cortisol story and better supported: fat has little direct effect on insulin compared with refined carbohydrate, and adding fat to a meal tends to slow how quickly that meal hits your bloodstream.
So olive oil on a salad is not doing something exotic to your hormones. It is changing the shape of the meal. Drizzled over vegetables, fish or chicken it improves the fat quality of the plate and tends to increase how satisfied you feel, which is usually what determines whether you go looking for something else an hour later.
That is a smaller claim than melting belly fat. It also happens to be true, and it is the sort of change that survives contact with a normal week.
Fat quality is one of the seven things our scanner scores, which is why a plate with olive oil on it lands differently from the same plate without. If you want to see how a meal reads before you eat it, the Insulin Fix Scanner gives you a single score and the one change that would help most. Three scans free, no card.
Frequently asked questions
Does olive oil burn belly fat?
Not in the direct way the popular claim suggests. There is human evidence associating high-polyphenol extra virgin olive oil with reduced waist circumference and lower inflammatory markers over a couple of months, mostly in people with metabolic syndrome. That is an association in a specific group, not a fat-burning effect, and the studies had people replace other fats rather than add olive oil on top.
Does olive oil lower cortisol?
There is no good human evidence for this. It is the weakest link in the viral version of the claim. Inflammation and cortisol are both real, and cortisol does influence where the body stores fat, but the specific chain from olive oil to lower cortisol to fat loss has not been demonstrated in people.
How much olive oil should I use?
The studies showing benefit had participants substitute olive oil for other fats rather than add it. Using it as your main cooking and dressing fat is the practical version. Talk to your doctor before making a deliberate change if you have a metabolic condition or take medication.
How can I tell if my olive oil is any good?
Taste a small amount on its own. A fresh, high-polyphenol oil gives a peppery catch at the back of the throat. That sting is the oleocanthal, so a bland oil is a tired one. Also check for a dark bottle, a harvest date, and "cold-pressed extra virgin" on the label.
Is the ibuprofen comparison accurate?
The mechanism is real. Oleocanthal inhibits the same COX enzymes ibuprofen acts on, which is what the 2005 Nature paper showed. The dose is not comparable. A culinary serving is far below a therapeutic ibuprofen dose, so it is not a substitute for anything your doctor has prescribed.
The short version
Good olive oil is worth buying, and most people are buying it wrong. The chemistry behind the peppery sting is real and the research behind it is solid. The cortisol story attached to it is not, and you do not need it: the honest reasons to use a fresh, dark-bottled, cold-pressed extra virgin olive oil are strong enough on their own.
Be a little more suspicious when a claim arrives with prestigious citations attached. Check what the cited paper actually measured. In this case three of the four claims held up, and the one that did not was the one carrying the promise.
Karl Jacob is the author of Fix Your Insulin: 7 Simple Hacks to Lose Weight Without Hunger or Calorie Counting. This article is for educational purposes and is not medical advice. Talk to your doctor before making any significant change to your diet, especially if you have diabetes, a metabolic condition, or take any medication.