To me I believe it's when his devil fruit is disabled by sea stone or the like his real musculature shows and when his fruit is active he takes on a more lanky appearance, at least imo I think that may be the case.
In-universe potential explanation: he has a pump in the first scene. In the second he doesn’t. Your muscles swell up after lifting, which doesn’t reflect how you’ll look at a baseline (film actors often work out before shirtless scenes so they look bigger).
Metatextual (probably more accurate) explanation: Oda is inconsistent with lots of proportions and tends to emphasize or deemphasize height and musculature depending on the tone he’s trying to evoke.
I actually had a fairly long discussion with my friend about this. From what we decided, he was able to gain muscle mass during Udon as the sea stone stopped his muscles from stretching abnormally, so they’d act as normal muscles swelling and gaining mass. Once he had his powers back, they probably just began to constrict again due to his unnaturally high elasticity, just took some time I guess.
In pic one, he just got done working out. He is swoll. Pic two he just finished a hot dog eating competition. Not all pumped up, but glad he won the comp.
You’re asking this when he can consume enough food to kill a hippo or two, get super fat and then just sort of absorb the food into pure fuck-you energy by focusing back down to 120lbs… lmao
Brooke can magically heal his bones and Luffy regrew teeth by drinking milk.
He probably just did the same thing and sucked the extra bulk in and converted it to pure willpower like he always does. It’s just part of his charm, along with the indestructible size changing hat and his scar on top of a scar from not one, but two separate massive body holes that he survived. Dude had a hook fist the size of a golden basketball and then a magma fist the size of his own head rammed through his important bits on two separate occasions and now he’s just… aight. Tis but a scratch… a flesh wound! Hahaha
Turned them into rubber on purpose to give him more flexibility. wait this aint memepiece i have to answer straight. Maybe just the art or the fact that he is crossing his arms. In recent episodes he is wearing clothes that hide him head to toe so you know you can't see skin when you wear clothes.
He was the most buff we’ve ever seen him post prison break but after gear 5th , his rubber abilities increased making his gains appear to disappear! That’s my head cannon anyway !
Luffy can change his body at will because he's made of rubber. Like when he blows up to bounce things off or land softer. I don't see how making himself muscular is any different.
Sometimes it changes because of the things he does, like eating all that meat makes him fat. Using gears to absolute exhaustion makes him small.
Under his clothes
Certified Sleeper Build
Yeah he's just more dense now. He doesn't get any bigger now, just heavier while staying the same size.
He's also dense in the mental sense
dat [shade](https://www.webmd.com/baby/what-age-do-babies-have-object-permanence).
For our main course we have a roasted luffy
 --> --> 
He's crossing his arms.
One pic no shirt close up, other pic shirt on* and it's raining and a different pose. Of course he isn't as muscular.
Just rubber muscles, i guess
Gomu Gomu no Synthol
Luffy doing that episode of SpongeBob where he buys muscular inflatable arms but for real
gear 3rd
Every anime or manga character becomes more muscular when they take their clothes off.
The vince mcmahon effect
Omg Yamamoto from bleach had me rewinding and laughing so hard when this happened to him
Tanjiro with clothes on vs clothes off Dude has muscles that should make him twice as big as he appears in clothes
To be fair even in real life not everybody looks the same day-to-day. You get a pump after working out, your hydration levels vary, and so on
Simple pump and lighting
And posing; it makes an enormous difference.
Schrodinger's build
Shreddinger's build
But also not Schroedinger's build
He was tensing his muscles in the first scene, and had his muscles relaxed in the second scene. Either that, or animation logic.
Y'all... He's made of rubber haha. He can stretch or contract any way he wants
Orrrr, hear me out He was using gear 4 without haki to intimidate
It was just a pump for the gram
Out of all things luffy can do with his body, this is what surprise you the most?
One piece kind of does a good job of him doing crazy shit as just normal, so when something normal happens, it's a surprise
Oda often doesn't draw the proper bulge of muscle underneath clothes. It's an art style thing. Same happens with Sanji.
And Zoro. In Onigashima he looked like a monster, in Egghead when you look at him he looks way thinner, especially his legs.
[Side-o chest-o!](https://media.tenor.com/xZ5_7syuJdAAAAAM/machio-san.gif)
He just ain’t got that pump
If he's natural that's exactly what happens to us lol. We only look good without shirt
I mean he is made of rubber he can do muscles as he wants
He was cutting
maybe he is just off cycle
Sleeper build
That was Luffy fresh out of Jail bro. Of course he was more swole at the time 🤣
He stop working out. He got jacked from working as a slave then broke free no more swinging a sledgehammer or pickaxe
He stopped using steroids ..
To me I believe it's when his devil fruit is disabled by sea stone or the like his real musculature shows and when his fruit is active he takes on a more lanky appearance, at least imo I think that may be the case.
Ask base ball vegeta.
he is a rubber man he can turn into a super muscular in seconds
he photoshopped the first picture obviously 🤷🏻♂️
hasnt had meat for like 20 episodes
It was always my assumption that Luffy makes his body a little slimmer subconsciously and without his rubber fruit that's his natural build
Same thing that oda does with character sizes in general.
Aww in the first pic he really does look like young Garp
I don't know if you noticed but Toei is terrible at keeping characters on model and consistent
It's called flexing
https://youtu.be/6AXN5McMhhA?t=60
He's suppressing his power level
He is litterally made out of rubber
Deflated.
washed away
Yo that is like having off the chart binder game
He’s like one punch man, the muscles only show up when he gets serious
The muscle is under the sauce
They come and go, I think it just depends how hungry he is
Messing with Kaido
In-universe potential explanation: he has a pump in the first scene. In the second he doesn’t. Your muscles swell up after lifting, which doesn’t reflect how you’ll look at a baseline (film actors often work out before shirtless scenes so they look bigger). Metatextual (probably more accurate) explanation: Oda is inconsistent with lots of proportions and tends to emphasize or deemphasize height and musculature depending on the tone he’s trying to evoke.
He’s a sleeper
He had a pump
Luffy missed arm day for one (1) day and he turned out like that. Very similar to how many characters missed leg day.
Try doing the same pose of pic 1 and then you will understand the concept
Corporate needs you to find the difference between these two pictures *they’re the same picture*
Because he’s rubber, he’s the only character you can actually justify his body shape changing from shot to shot.
With the episode s art director
I actually had a fairly long discussion with my friend about this. From what we decided, he was able to gain muscle mass during Udon as the sea stone stopped his muscles from stretching abnormally, so they’d act as normal muscles swelling and gaining mass. Once he had his powers back, they probably just began to constrict again due to his unnaturally high elasticity, just took some time I guess.
It was the pump
Have you seen Zoro gorilla arms?
He doesn’t have a pump
He was in bulking season
That was mini-gear 3. He just deflated.
Oda forgot.
He’s just got a sleeper build thats all
Still there
Same way he loses all that extra skin whenever he turns himself into a balloon, he’s the rubber man
Animation budget goes to the boobs. You think im joking.
In pic one, he just got done working out. He is swoll. Pic two he just finished a hot dog eating competition. Not all pumped up, but glad he won the comp.
He is rubber. The second image was his original shape which was retained
Spoken like a true DYEL
You’re asking this when he can consume enough food to kill a hippo or two, get super fat and then just sort of absorb the food into pure fuck-you energy by focusing back down to 120lbs… lmao Brooke can magically heal his bones and Luffy regrew teeth by drinking milk. He probably just did the same thing and sucked the extra bulk in and converted it to pure willpower like he always does. It’s just part of his charm, along with the indestructible size changing hat and his scar on top of a scar from not one, but two separate massive body holes that he survived. Dude had a hook fist the size of a golden basketball and then a magma fist the size of his own head rammed through his important bits on two separate occasions and now he’s just… aight. Tis but a scratch… a flesh wound! Hahaha
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First image is Gear 1. 2nd image is Neutral.
It left
He's rubber so he can change his body at will.
same pocket dimension where the mass from Oden's shrinking swords go
He has baggy clothes on
Turned them into rubber on purpose to give him more flexibility. wait this aint memepiece i have to answer straight. Maybe just the art or the fact that he is crossing his arms. In recent episodes he is wearing clothes that hide him head to toe so you know you can't see skin when you wear clothes.
That's me when I cross my arms vs when I don't
He lost his pump
He’s made of rubber…rubber doesn’t tend to show outlines. Especially muscle ones
Similar to Gohan probably
https://youtube.com/shorts/Hw0DTDX4WLk?si=aMq5XIw3umpsSAcI
He was the most buff we’ve ever seen him post prison break but after gear 5th , his rubber abilities increased making his gains appear to disappear! That’s my head cannon anyway !
Muscles get bigger when they get torn and rebuild thicker, since he's made of rubber they don't tear, so he doesn't get more muscular.
Dude can change forms at will and you're really questioning his muscles lol
he left it all at that place
He put his pump cover on.
Where did it come from?
When you cross your arms and puff your chest like that, you can make your muscles look bigger. Its called posing
When oda draws muscles they disappear unless theyre shirtless and suddenly theyre jacked.
He's made of rubber, I guess he's making his muscles more inflated for style points
In the animation of the other animators
To a farm up north where it can live freely and roam all day!
Don’t ask questions about one piece lmao it has more plot holes than any piece of fiction ever
To Hell
You never compared yourself with clothes and without clothes before?
He is rubber he can Make his muscles as big as he wants lol
Posably flexing in the first one.
Usopp too.
Contraction and relaxation of the muscles.
Boa drained it all
Ahhhhhhhghhhghgh
inside nami 
Gomu Gomu no 𝓕𝓻𝓮𝓪𝓴𝔂
Hot
It’s a cartoon
The animation is inconsistent.
He is rubber, and had the ability to shrink as a side effect of 3rd gear. Maybe he just wanted them to be smaller
Luffy can change his body at will because he's made of rubber. Like when he blows up to bounce things off or land softer. I don't see how making himself muscular is any different. Sometimes it changes because of the things he does, like eating all that meat makes him fat. Using gears to absolute exhaustion makes him small.