All Might's true form. This is All Might's skinny true form.

I’ve watched all four seasons of My Hero Academia and the two movies that accompanied it, but there’s a question that still keeps nagging me. Which is All Might’s true form? Skinny or Muscle? This question might seem insignificant because, in the grand scheme of things, the answer doesn’t matter. Regardless which is his true form, All Might is undoubtedly the strongest hero the MHA world has ever seen. However, senpai will still try to answer this lingering question for those who are curious to know.

In a previous post, I talked about what I learned from Heroes Rising, and that didn’t require much research. I knew what I had to write. In this case, I had to analyze the show again while tying up other people’s opinion on All Might’s true form into one main idea. Tell me if I got it right.

In short

All Might’s true form is both skinny and muscular, but it depends on the timeline. In the anime, it’s shown that he was scrawny when encountering the previous One For All user. After obtaining the quirk, he is seen muscular in flashbacks, and this is due to his effort and nothing to do with One For Alls power. Due to his injury from the fight against All for One, All Might starts to lose muscle mass as his body isn’t able to sustain that form any longer.

All Might's true forms timeline explained. From different hero ages we can see that All Might has different true forms
credit to @sandypsyche. Note that the timeline is slight off in terms of All Might’s age and hero era. It still is a good depiction of his life’s timeline.

Pre-quirk age

All Might's true form when he was a kid before receiving his quirk. All Might's true form at this point is skinny Johhny Bravo

As we all know, All Might was born quirkless just like Deku. During this period of time, we can see that All Might’s true form is similar to a skinny Johnny Bravo and lacking the big muscles he’s well known for. Many people make the mistake of thinking that this is his true form, and the muscle that develops afterwards is due to One for All.

Wrong.

All Might managed to inherit One for All and use it to the full extent of its power during the time he received it. What does this tell us? We have to look at it from two perspectives which are from the quirk and the user.

The quirk

One for All isn’t as strong as its commonly perceived. So, what’s so special about it then? It’s the potential of what it can be. The effort of those who inherit this quirk will determine how strong it can become. Due to its unique nature, One for All can never decrease in power. Its power can only stay constant, or increase due to the efforts of the user currently wielding it.

The user

Based on the nature of the quirk, I think it’s safe to say that the previous One for All users weren’t that strong because of how All Might was able to use it at a 100% upon first receiving it. All Might is what made One for All strong until Deku couldn’t even utilize it even after going through intense training for 10 months.

Basically, at this time of All Might’s life, his true form would can be called skinny Johnny Bravo.

Post-quirk and hero ages before All for One battle

All Might's true form throughout his hero ages. He is muscular and this is All Might's true form

During this era, we can see that All Might is as big as hulk. Like I said before, this is due to his hard work, but the quirk enables him to surpass his normal human limits. The element of stockpiling raw power in One for All allows this to happen. The way I see it, One for All can be compared to steroids in real life. In my theory, as long as the person who inherits One for All tries to surpass their limits by training, One for All will allow their body to adapt so that they can contain that raw power.

As you can see in the picture above, All Might’s body becomes more refined over time. One for All only enables him to surpass his limits through sheer hard work.

So Muscle form during this time frame is All Might’s true form.

Downfall era – First fight with All for One

All Might's true form after getting injured from the fight with All for One

During this timeline, All Might manages to defeat All for One but at a very high cost. He loses his stomach, and his respiratory system gets impaired.

If I’m not mistaken this takes place during the Golden Age. If we compare the previous picture to the above one, we can see that All Might is shrinking. This makes sense because when you don’t have a stomach, your body can’t metabolise nutrients as efficient as before, and this results in the muscles not receiving sufficient protein for muscle retention.

Not only is his body deteriorating in terms of muscle mass, but he also can’t utilize One For All to the maximum anymore. As explained above, One for All cannot decrease in power and because of this, All Might has to force his body to adapt to that immense power that he cultivated throughout the years. This is why we see him change into a form which he calls as Muscle Form.

This not his true form. This is the only way for him to use All for One at a 100% but for a limited time.

All Might's true form .injured.
This will eventually be his true form after the battle with All for One

The final battle with All for One and becoming quirkless again

All Might's true form. This is his final battle with All for One which made him be forever skinny Johnny Bravo true form All Might.

This is the ending of All Might’s story as a hero. After passing down All for One to Deku, the thing keeping him going is the remaining reserves of his quirk. The final fight with All for One forces him to use everything he has left and eventually leaving him quirkless.

I find it very symbolic because his life went full cycle but that’s not the point.

The point is that after this fight, All Might can no longer force his body to adapt to a power that’s not there anymore. Meaning, he couldn’t change to Muscle Form even if he wanted to. We still see him doing it from time to time for a second or two, but I think that’s just for comedic purposes, or because of the ashes that’s left from One for All.

From this point until the day he dies, All Might’s true form is skinny Johnny Bravo.

Conclusion

This what I could gather from my own while tying it up with the ideas of other people online. I hope this answer satisfies you, and if it doesn’t let me know why.

I find that One for All is a very symbolic quirk because I feel that it represents the world as we know it. We are constantly evolving as time goes by, but we couldn’t have done it without the knowledge from our ancestors. Isn’t this fascinating? We search for the truth based on the ideas left behind by our predecessors. To ensure their lives weren’t in vain, they pass the baton to us, the future generation.

I leave the rest to you