Health Claims

Barbell curls make you slightly stronger when your arm is almost straight, but not enough to matter much in real life — the difference is tiny.

Quantitative

Doing preacher curls 3 times a week for 10 weeks makes your biceps bigger and stronger, no matter if the exercise feels hardest when your arm is straight or bent.

Causal

Whether your preacher curls are hardest at the start or end, you still get just as strong in the middle and fully bent positions after 10 weeks.

Causal

If you do preacher curls with a barbell (harder when your arm is straight), you get stronger at keeping your arm slightly bent than if you use a cable machine (harder when your arm is fully bent).

Causal

Whether you do preacher curls with a cable machine (harder when your arm is bent) or a barbell (harder when your arm is straight), your biceps grow about the same amount after 10 weeks of training.

Causal

Even people with type 2 diabetes can see their muscles start working like healthy muscles again after losing a lot of weight — and it’s not because they make more sugar transporters, but because the ones they have work better.

Correlational

After losing weight, muscles get better at using sugar not because they make more GLUT4 proteins, but because the existing proteins move to the right place or work better.

Mechanistic

When people are extremely overweight, their muscles are much worse at pulling sugar out of the blood — even when insulin is present — but this gets much better after they lose weight.

Correlational

Even though muscles get better at using sugar after weight loss, the amount of the GLUT4 sugar transporter protein in the muscle doesn’t change — so something else must be making it work better.

Correlational

When very overweight people lose a lot of weight, their muscles get much better at using insulin to pull sugar out of the blood, which helps fix their diabetes or prediabetes.

Correlational

If you do leg exercises with your knee only slightly bent, your muscles stay strong at that angle—even right after the workout—but if you do them with your knee fully bent, your muscles get weaker at that angle and also at other angles.

Causal

After doing leg exercises with your knee bent all the way back, your muscles are weaker not just at that angle—but even more so when you try to use them with your knee only slightly bent, as if your muscle fibers got stretched out and lost their normal power.

Mechanistic

When you push hard with your knee bent all the way back, your thigh muscles have to work much harder internally than when your knee is only slightly bent—even if you’re pushing with the same force on the machine.

Causal

Even though your muscles feel just as sore and your blood shows similar signs of damage after doing leg exercises with your knee bent far back or only slightly bent, your muscles are actually weaker and harder to activate for longer after the deep bend version.

Causal

Doing strength exercises with your knee bent further back makes your muscles weaker and harder to activate for up to two days afterward—even when you’re testing them at different knee angles—compared to doing the same exercise with your knee less bent.

Causal

One way the liver breaks down alcohol doesn’t mess up the cell’s energy balance like other ways do — so it might be a safer way to clear alcohol, even if it’s not the main one.

Mechanistic

A natural switch in the liver (PPARα) that turns on fat-burning also turns up a cleanup enzyme (catalase) that helps remove alcohol — but this can accidentally make liver damage worse by creating too much hydrogen peroxide.

Mechanistic

When the liver breaks down fat in tiny compartments called peroxisomes, it makes hydrogen peroxide — and that same chemical can help break down alcohol faster, especially if you eat a lot of fat.

Mechanistic

When the liver uses a specific enzyme (CYP2E1) to break down alcohol, it accidentally creates harmful free radicals that damage liver cells, especially with long-term drinking.

Mechanistic

When the liver breaks down alcohol, it creates a chemical imbalance that stops the liver from burning fat, causing fat to build up in the liver.

Mechanistic

When too many fat molecules and inflammatory signals from belly fat reach the liver, it becomes less responsive to insulin.

Descriptive

Where fat is stored in the body — especially around the organs — is linked to how the liver processes energy and how sensitive it is to insulin.

Descriptive

Fat around the organs sends out chemicals that talk to liver cells and immune cells inside the liver.

Descriptive

Fat around the organs sends out fat molecules and inflammatory signals directly into the liver through a major blood vessel.

Descriptive