Browse evidence-based analysis of health-related claims and assertions
People who eat a lot of meat have specific chemicals in their blood—ketones, BCAAs, and TMAO—that show their bodies are burning fat for energy, breaking down protein, and their gut bacteria are processing meat in a unique way.
Descriptive
Humans have a gut that's shorter than herbivores' but longer than carnivores', which evolved to better digest meat and fat instead of plants, freeing up energy for our big brains.
Not all trans fats are the same — some dairy fats lower diabetes risk, one dairy fat raises it, and artificial trans fats don’t seem to matter at all. What matters most is the exact molecular shape, not whether it’s natural or artificial.
Correlational
A fat called trans-palmitoleic acid was once thought to protect against diabetes, but when scientists accounted for other similar fats in dairy, the link disappeared — meaning the earlier belief was probably wrong.
The artificial trans fats found in fried foods and margarine don’t seem to raise the risk of type 2 diabetes when looked at on their own, which surprises many people who think all trans fats are bad.
A different type of fat found in dairy called c9t11-CLA is linked to a higher chance of getting type 2 diabetes, which is surprising because other dairy fats are usually thought to be harmless or even helpful.
A specific type of fat found in dairy called t10c12-CLA is linked to a lower chance of getting type 2 diabetes, even when accounting for how much cheese or butter someone eats.
People with more of a specific fat found in dairy products like butter and cheese in their blood have a lower chance of getting type 2 diabetes, even after accounting for how much dairy they eat.
Eating more total saturated fat — like butter or cheese — doesn’t seem to raise the risk of high blood pressure, diabetes, or high cholesterol in this group of Italians, which goes against what many health guidelines say.
People who eat more fish oil or fatty fish — which contain EPA — are much less likely to have high blood pressure, possibly because EPA helps relax blood vessels and reduce inflammation.
People who consume more of a rare fat called C20:1 — found in some processed oils — are more than twice as likely to have high cholesterol, high blood pressure, or diabetes, possibly because this fat harms blood vessels or metabolism.
People who eat more olive oil and nuts — which are rich in oleic acid — are much less likely to develop diabetes or high blood pressure, possibly because this fat helps the body use insulin better and keeps blood vessels healthy.
People who eat more of the short and medium fats found in dairy and coconut oil are much less likely to have high cholesterol or diabetes, possibly because these fats help the body manage blood sugar and fats better.
As Americans started eating more processed vegetable oils, rates of insulin resistance and diabetes went up at almost the same time—this timing suggests the two might be connected.
In mice, eating lots of soybean oil makes them fatter, more insulin resistant, and gives them fatty livers—worse than eating coconut oil—even when they eat the same number of calories and fat.
Quantitative
If too many cells start burning sugar instead of fat, blood sugar can dip too low between meals—this tricks the body into releasing stress hormones that block insulin, leading to high blood sugar and high insulin at the same time.
Mechanistic
When cells are stressed by too many processed oils, they may switch from burning fat to burning sugar—even when oxygen is available—similar to how cancer cells get energy, which might be a survival tactic that backfires for the whole body.
Over the last 50 years, the fat stored in our bodies has changed—more of it comes from processed vegetable oils, which might be changing how our body burns energy.
The highly processed vegetable oils we eat a lot of today—like soy and canola oil—can cause damage inside our cells because they break down easily and lack protective nutrients, which might mess with how our body uses energy.
Even though many countries have banned artificial trans fats, you can still find them in baked goods, fried foods, and snacks in places where rules aren’t enforced or labeled clearly.
Eating artificial trans fats might change how your genes work without changing the DNA itself, possibly making you more prone to inflammation and fat buildup in the liver — but we don’t yet know how this works in people.
Artificial trans fats make your body produce more inflammation and cell damage, which can lead to heart disease and other chronic illnesses.
Trans fats from dairy and meat don’t seem to harm cholesterol or cause inflammation like the ones made in factories — some might even be a little good for you.
Artificial trans fats make the liver produce more fat, cause more cell damage from oxidation, and trigger inflammation, which can lead to serious liver scarring over time.