How low does a bodybuilder's body fat really go?

Short answer

Right before a contest, men were at 5.8 to 10.7% and women at 8.1 to 18.3%. Single cases reached 4 to 5%, but the same body read 4.5 percentage points apart on different machines, and it returned to normal within months after the contest.

How low does a bodybuilder's body fat really go?
'Bodies on stage are at 3% fat' — is that true?
Bodybuilders on a contest stage look like they have almost no fat. We used studies to check how low body fat really goes, how accurate the number is, and how long it lasts.
Right before a contest: men 5.8 to 10.7%
Women were at 8.1 to 18.3%
A 2023 analysis of 16 studies found body fat right before a contest was 5.8 to 10.7% in men and 8.1 to 18.3% in women. Early in preparation it was 9.6 to 16.3% in men and 15.3 to 25.2% in women. Body fat percentage dropped by 30 to 60% during preparation.
Tracking single people, it reached 4 to 5%
8% fell to 4.5% over 6 months
A study that followed 1 person for 12 months around a contest saw body fat fall from 14.8% to 4.5% over 6 months of preparation. Another person went from 88.6 kg to 73.3 kg and from 17.5% to 7.4% body fat over 26 weeks.
But the same body read differently on each machine
6% on one, 5.1% on another
In a study that measured 1 person for 8 months, body fat right before the contest was 9.6% on an air-displacement machine and 5.1% on an X-ray scanner. After 27 people dieted for 4 months, their average body fat was 12.7% by X-ray, 11.6% by an electrical scale and 18.3% by skinfold pinching.
The number did not last
Body fat went back to normal within months after the contest
1 person who had reached 4.5% was back at 14.6% within 6 months after the contest, and another who had reached 5.1% was at 13.8% after 5 months. Of 27 people, 6 were under 10% right after the diet, and none were after 3 to 4 months of recovery.
The body paid a price on the way down
Testosterone fell to about a quarter
1 person who got down to 4.5% saw testosterone drop from 9.22 to 2.27, about a quarter, and resting heart rate fall from 53 to 27 beats a minute. 27 people who dieted for 4 months lost about 12% of body weight and had more menstrual irregularities.
Bottom line: men 5 to 10%, women 8 to 18%
Only briefly, and machines differ by several points
Measured body fat right before a contest was 5.8 to 10.7% in men and 8.1 to 18.3% in women, and the lowest records were 4 to 5% in cases of 1 person. The same body read 4.5 percentage points apart on different machines, and it returned to normal within months after the contest. Read stage numbers as a record of a body held for a short time.