Which supplements do bodybuilders actually take?

Short answer

Creatine and whey protein. Of 235 competitive bodybuilders, 95.7% took supplements, and creatine was the most common at 80.4%. Winners and non-winners took the same list of supplements.

Which supplements do bodybuilders actually take?
'A stage-ready body = special supplements' — is that true?
Many people assume competitive bodybuilders take secret supplements nobody else knows about. We used surveys and trials to check what they really take, and whether it relates to their results or their muscle.
How many take supplements?
Almost all of them, and creatine came first
A survey of 235 competitive bodybuilders found that 95.7% took supplements. The most common were creatine (80.4%) and whey protein (65.8%). An earlier survey of 127 bodybuilders found that every single respondent took supplements.
What about drug-tested natural bodybuilders?
Creatine 92-95%, whey 89-95%
A survey of 56 natural bodybuilders from 18 countries during contest prep found that 92-95% took creatine and 89-95% took whey protein. More than half (54-58%) also took caffeine. BCAAs were at 26-30%.
Did winners take something different?
Their supplement lists did not differ
Among the same 56, the 19 who had won a contest and the 37 who had not showed no difference in supplements, drinks, or how they bought them. Creatine use was 94.7% vs 91.9%. What set winners apart was that they were older and had longer competitive careers.
What did drug users take more of?
Amino acids on the drug side, creatine on the natural side
Of 187 bodybuilders, the 40 who reported using drugs took more BCAAs and essential amino acids. The 147 who did not use drugs took more creatine.
Do those two really build muscle?
Creatine 1.14 kg, protein supplements 0.30 kg more
An analysis that pooled 12 studies found that adding creatine to strength training increased lean mass (muscle and everything except fat) by 1.14 kg more. An analysis of 49 studies with 1,863 people found protein supplements added 0.30 kg. Above about 113 g of protein a day for a 70 kg (154 lb) person, gains did not increase further.
Where do they buy, and whom do they ask?
Most bought online and chose for themselves
Of the 56 natural bodybuilders, 71-79% bought supplements online and 52-58% chose them on their own. They asked a health professional such as a doctor or dietitian less than 10% of the time.
Summary: there was no secret
Two proven basics, creatine and protein, at the center
What most bodybuilders take is creatine and whey protein, and both have evidence of adding muscle alongside strength training. Winners' supplement lists were no different. Protein is best seen as a way to reach your daily total (about 113 g for a 70 kg person).