My 97 year old mother is in Independent Living with some assistance. I spend one afternoon a week with her. She has had several strokes, which she calls TIAs, and is mobile with a walker, but has bladder incontinence and some bowel, as well, and uses protective underwear. She should be drinking water and other liquids, but avoids them, because they increase her urinary output. She also claims that water gives her diarrhea, which pretty clearly is from other reasons. I think she feels she has a bit of control if she doesn't have fluids, and she won't acknowledge that dehydration could bring on another stroke, in spite of medical advice. Should I just give her the freedom to choose how she wants to live (or die)? She is pretty rational, lucid and active for her age, though her stamina is understandably low. My sister and I are perplexed over whether we should let her live life on her own terms (she's pretty happy) or constantly try to get her to do what we and other authorities think is best for her. When we discuss topics like this with her, she understands and seems agreeable to some changes, but in practice, she does it "her way". We are starting to feel that this is a quality of life issue and we should stop badgering her--lovingly--and let her live her own choices, even though we find this worrisome and frustrating. She is not being neglected in any way, but she is not supervised in her living situation, so she can do as she pleases.
Elderly or otherwise, none of us make all the right choices to extend our lives. How many of us exercise the way our doctor thinks is best for us or eat the diet our doctor tells us promotes the longest lives? Very few of us, it seems. As such, we should be careful about judging others regarding their "bad" decisions when ours probably aren't as good as we like to pretend they are, either.
The other thing, here, is the issue of "quality of life." I'm not saying to just give in and let Mom do just anything she wants if it happens to be really dangerous or detrimental, but I'm just saying that you have to place some value on her happiness.
From my own experience, prioritize these things and decide very analytically which of these battles are most important, in your mind, which you think you can win, and what the likely outcome will be. If you'll just end up constantly on her case with no change from her in sight, that probably isn't worthwhile -- spend your efforts on something where you can make a real difference.
One of his caregivers gave him watermelon which he loved, which has a lot of liquid. She also gave him fruit juices mixed with cranberry juice, which is good to help keep urinary tract infections at bay.