Fitness claims, checked
Fitness claims from your feed, checked against the studies.
We take the fitness rules that travel fastest on TikTok, Instagram and gym forums and check them against meta-analyses and official guidelines. Six sentences per claim, the numbers drawn, every study linked.
From the ledger
“Cold plunges after lifting speed up your gains”
Doesn’t hold up (1 of 4)
Cold plunges can ease soreness, but taken right after lifting they tend to slightly blunt gains in muscle size and strength.
Read this checkClaims checked
8
Each with six sentences and at least two charts.
Sources cited
38
Meta-analyses, reviews and official guidelines.
Newest evidence
2026
We use the most recent pooled evidence we can find.
Verdicts
4 · 4
4 partly true · 4 doesn’t hold up.
The ledger 8
Eight claims, eight verdicts.
Each row opens the full check: the claim, six sentences on what the evidence says, the numbers drawn, and every study we read.
- 01“You need 1 gram of protein per pound of body weight to build muscle”More protein helps lifters, but gains level off near 1.6 g/kg, about 0.7 g per pound, making 1 g per pound a generous ceiling.
- 02“10,000 steps a day is the magic number”More steps are linked to lower risk of early death, but most of the benefit arrives by 7,000 to 8,000 steps.
- 03“Creatine is just water weight, and it hurts your kidneys”Creatine holds a little water at first, but with lifting it adds real lean mass, and trials show no kidney harm in healthy people.
- 04“Ab workouts burn belly fat”Training a muscle does not meaningfully burn the fat over it; regular whole-body exercise is what reduces belly fat.
- 05“Cardio kills your gains”Adding cardio to lifting does not reduce muscle growth or maximal strength on average, though same-session cardio can blunt explosive power.
- 06“You have to train to failure to grow”Hard sets that end close to failure help growth, but actually reaching failure is not required for most people.
- 07“Cold plunges after lifting speed up your gains”Cold plunges can ease soreness, but taken right after lifting they tend to slightly blunt gains in muscle size and strength.
- 08“Fasted cardio burns more fat”Fasted cardio burns more fat during the workout itself, but over weeks it has not led to more fat loss than fed cardio.
How we check
Three steps. One straight answer.
The full rules are on the method page, including what we won’t do.
- 01We collect the claims.We note the fitness rules that keep coming back on TikTok, Instagram, YouTube and gym forums. We don’t quote or name the people who post them.
- 02We read the evidence.Meta-analyses, systematic reviews and official guidelines come first. Every number is traced to the abstract or full text it came from.
- 03We explain it in six.Six sentences, the key numbers drawn as charts, and a plain verdict. Caveats and sources sit on every page.
The verdict scale
Four verdicts, one scale.
The blocks show how much of the claim, as people usually say it, the best evidence supports.
- Holds up (4 of 4)
The best evidence supports the claim as people usually state it.
- Partly true (2 of 4)
Part of it holds up, but the number, the scope or the certainty is off.
- Doesn’t hold up (1 of 4)
The best evidence contradicts the claim, or the effect is too small to matter.
- Too early to say (0 of 4)
There isn’t enough good evidence yet to call it either way.
Not medical advice
General information, not medical advice.
If you have a health condition, talk to a clinician before changing your training or supplements.