I've been thinking a bit about solving this same problem, but I feel there is too much overhead to log things manually.
What we need is better interfacing with computers so that we can just think "log my weight is 190 lbs" or "log I ate 1 small chicken breast and a cup of brocolli". Voice control and my phone are not sufficient for my needs so far. I also want to be able to have full control over my own logs in plaintext.
I want to be a cyborg already...
I used https://open.nomie.app when i had to take a medicine for several months and wanted to know how my body reacted and how the symptoms changed.
I used tickmate to track symptoms. It's a one bit journal for android.