Well, it depends on the level of canon you are looking for..
and, yes.. I know, with
Doctor Who, that's a tricky issue.
But, still.. If you are willing to accept one of the comic books , then we have an example of an adult:
Nothing is said about it's weight, but it's appearance
is basically just a larger version of the baby ones we saw in the episodes.
The size is even questionable, since there really isn't anything to compare to to, to get a good idea of the scale.
But in appearance, it's very similar to the baby version.
scifi.stackexchange.com/users/2292/K-H-W
I don't believe this was every mentioned so far.
However something to consider, when the 10th doctor was dying he visited Jack at a bar.
There was an adipose creature there; your first reaction would be to think 'oh and adipose baby' -
but why would a baby be in a bar?
Maybe the adults look exactly the same.
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Doctor
Who screenwriter Russell T. Davis drew a rough concept art sketch of the ' Shadow Proclamation debating chamber ' for the two-part episode
The Stolen Earth/Journey's End .
Although it was ultimately filmed differently, to the right you can see an adult Adipose, basically identical to the child Adipose, but roughly twelve feet tall and presumably weighing a metric ton.
" The Shadow Proclamation, as Russell imagined it".
Illustration by Russell T Davies - From Doctor
Who: The Writer's Tale
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On the wikia page it says that the adult adipose look the same as the children but are twice the size of adult humans
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I personally think they would stay the same.
They are made of human fat so to speak, but once they "become" adipose, they wouldn't consume any more of the humans fat so would probably not develop any more.
I suppose if they stayed inside the human for longer they could grow and become larger, but it makes sense that they stay the same once no longer a part of that human - unless they were able to "feast" on more human fat which we never really find out
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In the episode Partners in Crime we see numerous "baby" adipose:  It's made clear these are infant adipose and are all about 1kilo in weight and are about 6-8inches tall.  But we never see what an adult adipose looks like (at-least in that episode), so what do they look like, how big are they, how much would one weigh?
What does an adult Adipose look like?
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Nothing is said about it's weight, but it is basically just a larger version of the baby ones we saw in the episodes. An adult adipose is a larger version of a baby one; there is no exact information available on its weight.
An adult adipose is a larger version of a baby one; there is no exact information available on its weight.