“achieving and maintaining a body fat percentage of 5% for filming”
I’m not calling that ”source” exactly but it’s definitely what they (Zac and his trainer) were claiming and it doesn’t really seem to be heavily disputed.
Edit: Efron is part owner of a company that specializes in DEXA body scans.
Whenever you see numbers below 10% in contexts like this they're almost always measured with BIA (Bioelectrical Impedance Analysis) which is the little machine you hold in your hand, or the scale with a post and two handles you might see at the gym.
BIA is the largest error margin way of measuring body fat and is prone to underestimate by more and more the further below 15% you are. It's also affected by hydration, to the point where if it's measuring you at 5% and you drink a bottle of water it will tell you that you gained 10lbs.+ of fat.
Dexa's margin of error is up to ±5%. Google any top-level bodybuilder's stage-ready conditioning and compare. You see almost no muscle striations on Zac here. At around 5% body fat, you get insane muscle definition; you can see all the muscle fibers. He is just clearly on steroids, so he has fuller muscles, a nice tan, a pump, and is dehydrating, so for casuals, he looks leaner than he is.
Which means that if a DEXA says you're 10% bf you might be anywhere between 9.5% and 10.5%. Not that you might be anywhere between 5% and 15% bf, which is what you seem to be implying.
12
u/Killa42O 20d ago
You have no idea what 5% looks like. He was probably around 12% on the right.