You sure about that? I can't find anything online about any of the three body shapes influencing the number of days an elder gets to live...

Nope, it has no affect on how many days a sim gets as an Elder. When I was modifying Almighty Hat's aging hack, there was nothing I came across that showed fitness affecting lifespan. None of the conditions that set that variability for days left for an Elder refer to fitness. The only thing about a sim that does have an affect is the sim's aspiration level on aging up.

Well that's interesting. I was under the impression it mattered but maybe it's TS3 I was thinking of? My brain is so fuzzy any more that even on good days I confuse stuff.

My sims gain a little fitness during woohoo so they are all super fit, I have no use for fat morphs.

@Orphalesion

Yes

And you are sure....how? Have you seen the code that makes it so that fit Sims gain days to their lives? And how many days are that? Or do fat Sims lose days? And how many?

Sorry, I don't mean that in any negative or dismissive way, I'm just really interested in the obscure workings of the game. ANd in this case it would also help me with fine tuning Inge's Adjustabel Aging mod for my game.

Okay then:
1. I have played the vanilla game for years, because I did not know mods existed. So I noticed it there first.
2. Most of the elders in my hood are born-in-game.
3. While it is possible to make one live longer than another one by using elixir of life, my experience is that if you don't do that, the fitter one will survive longer than the other one - even when all other things are equal, like aspiration points and rewards.
4. I have had many elders adopt a child, especially those who never had any. So I know that one of them will die normally, when it is time, and one will hang on until (at least) the kid''s teen birthday. It is always the fitter one that is left to look after the kid.
5. Without kids (or kids that are already teens) the number of days does not seem set - sometimes it is one day, sometimes it is more - taking into account that they may not be the same age. The younger, unfit one may indeed die before the older, fitter one.

Now i don't really know much about the internal workings of the game, but I would be very surprised if it is purely by chance that the fitter one seems to live longer!

Thank you for the explanation.
Bother that it's just observation and not actual code related stuff. Not saying that observation can't be valid, I was just hoping you might have information about which part of the elder aging code did that. As far as I understand from using Inge's mod, there's 5 lines that add/subtract days to/from an Elder's life and the only info I have on how they are determined (from Inge's website) is that they "relate to events in a Sims life", so it is very possible that fitness is one of the factors, but it is very frustrating that there's no way to tell which part it is (because frnakly I'd probably increase that difference). Because I've been playing around with that mod for a very long time to find an elder-lifespan that's neither too long nor to short for me.
And it's difficult to work with factors where you don't know what they're doing...(even if there's some good evidence that an aspect might be involved)

In an un-modded game elder's age duration varies by Aspiration Level only. In spite of in-game birthday warnings, elder is the only age that does that. Fit/fatness is not considered at all.
The code is in the age controller 'Get in Temp 0 - Age Duration'.

So I am just excellent at fulfilling fitness-related wants?

That is, I think, perhaps possible - the buggers always want to get fit the day after a particularly fattening dinner party

Thank you, I thought so.

Do you know anythign more about those 5 lines in the BCON that can influence the length of the Elder stage?

The code calculates a number between the 'Elder Min' and Elder Max' constants (Plantelder Max and Plantelder Max for plantsims), it uses the sim's GUID to get a random number between the values not it's random number generator so it is truly random for each sim. It then adds the '* Elder Bonus' depending on Aspiration Level.

It does use the 'Age Min and Age Max' constants for all ages, but for all except elder the min and max values are the same so there is no variation. That does mean age mods could add a variation on other ages if desired.