Older Mandy Moore looks like Diane Keaton

Just because you said so doesn't make it true 

I see no resemblance at all to Diane Keaton, who is much more attractive at any age than Mandy Moore..:JMO.

I agree. She almost walks like a pregnant person too and she has an odd pursed-lips thing going on. Not very believable but whatever. Still a great show.

I think she manages to portray an older woman very well, actually. She's added that stiff dignity in a very true to life way. Some people do get more stiff in their posture in older age, as they have had life experiences where they've had to become tougher and harder and a bit more displaying of dignity and standing taller and firmer, rather than the fluidity and slouching of a younger person. I know I carry myself a bit more "nose in the air" than I did when I was younger because you kind of start realizing you need to signal that you're not to be messed with. I think Mandy's doing great with the aged version of her character. I'm convinced by her portrayal of someone more my age, and impressed at how it contrasts to her younger self.

And the pursed lip thing -- yeah I'm doing that more in my older years too! Another trait I recognize. Again, a lot to do with life making you more steely and inclined to purse your lips about a lot of stuff. She's nailing it as a type of older person who's been through a lot.