I think I worked it out and I’m dead serious about this, this isn’t a joke. A character is at their peak when they are at their oldest age where they still have their original hair color.
![](https://www.opfanpage.com/wp-content/uploads/2020/05/2-2-1-1024x565-1.png)
Aging in One Piece works differently than in our world. In our world, our peak is somewhere between 25-30 years old. But I doubt this is true in the One Piece Universe. Kaido and Big Mom are said to be stronger than ever and they are 50-60 years old.
![](https://www.opfanpage.com/wp-content/uploads/2020/05/kaido_vs_big_mom__one_piece_ch__951__by_fanalishiro_ddd5azk-fullview.jpg)
Characters can also live up to 140 years old or more.
![](https://www.opfanpage.com/wp-content/uploads/2020/05/Kureha_Anime_Infobox.png)
Characters in One Piece also tend to keep getting stronger in a linear pattern unlike real world. However, Oda can’t really make a 100 years old human stronger than that same person at 30. So he uses hair decoloration to show that they have passed their prime.
![](https://www.opfanpage.com/wp-content/uploads/2020/05/one_piece_957___monkey_d_garp_by_melonciutus_ddhaa6i-fullview-1024x406-1.jpg)
Maybe it makes sense that Sengoku went white hair 2 years after his retirement.
![](https://www.opfanpage.com/wp-content/uploads/2020/05/Sengoku_Reverting_To_His_Human_Form-1024x540-1.png)
He stopped training hard and started relaxing a lot more and thus got weaker/passed his prime.
*by yincels