On March 29th 2018, I had my body fat calculated via hydrostatic weighing. I was surprised that it was so high and I decided to try to lose body fat to see how that would affect my life, including both my mental abilities (I'm a professional computer programmer) and my fitness (I was a search and rescue volunteer until January 1st, 2021 and I am an amateur ultra runner).
I started out with two files, one that documented the stats that I got back from the University of New Mexico as well as my interpretation of the stats and my plans (and results) of various changes I made, and a few days later a simple text file that documented everything I ate. Initially I tried to calculate things like my caloric intake and the grams of protein I was consuming and how many calories I was burning, but eventually I decided just having a log of what, when and how much was sufficient to keep me on the right track.
I've shared the food log with people a few times, because both my weight loss (if you see me in person) and the resultant physical performance boost (if you look at my UltraSignup results) have been fairly substantial. I had very mixed feelings about sharing them with the public, but decided to do so as long as everyone is aware that I'm not a doctor, dietitian, or coach. I do not recommend my diet to others as anything other than an "existence proof", in that it documents my calories in and I appear to be fairly healthy, although there's no guarantee that I'm not increasing my risk of cancer or heart disease, stroke, etc.
For what it's worth, I've been vegan since 2012 (and vegetarian for about thirty years before that), and supplement with B-complex, so I don't think it's particularly likely that I'm nutritionally deficient, because I think there's been long enough for such a deficiency to negatively affect my performance if not my health.
At the end of September 2023, I decided to get some blood work done and everything except my absolute lymphocytes was in the normal range. My lymphocyte count was a little low, but that's not concerning to me since my immune system seems to be working exceedingly well and I've been under a bit of stress for the last few months.
Although I used to feel uncomfortable making this data public, I eventually got over it. I have a bunch of other data (i.e., I track my daily training, typically running six days a week and bicycling on the seventh) and I've made some of that available, beginning with an overview of what I do is already available in my Bataan Memorial Death March training log. I joined Strava when the response to covid separated me from many people I was normally running with.