Beautifully written—thanks for sharing this! Please keep us updated, if you like.

(Edit: Even if this was fiction, or fictionalized, I still enjoyed it.)

I like the idea of relinquishing control over my body and submitting to the will and desire of another person, so this is appealing.
Also, the scenario of “waking up huge” is intriguing—like Franz Kafka’s The Metamorphosis (wherein a man wakes up in the body of a giant insect).
I’d enjoy using the gain button on my ‘victim’ each time they go to the gym to work out, or maybe when they’re in the middle of a run.

*Being* supersized is as tantalizing for me to imagine as *becoming* supersized. It’s not only the destination, it’s the journey.

(The following is one example of a personal passing fantasy. I hope no one is offended by it.)

I would have to gain 250 lbs. to make it to 500. In order to gain such an extreme amount of weight, I’d need a lot of help. So I fantasize about an arrangement where several people are entirely devoted to my huge gain—say two dominant feeders and a “trainer” who keeps me motivated and documents my progress. Day by day, I get fatter and fatter. My capacity increases along with my appetite. My mobility decreases. I’m transforming. The person I once was—the “skinny guy”—is further and further in the rear-view mirror. Terror grips me when I realize he’s gone forever, but food has become my pacifier. My feedeers shovel in a mountain of buttery syrupy pancakes, and I feel tremendously exhilarated. This is my life now. I’m voluntarily embodying the stereotypes and misconceptions society holds about the super obese: no willpower, lazy, greedy, gluttonous…

Today’s the day. It feels like a second birthdate. I look up from the bed and around the room for my helpers, but they’ve gone. I’m too excited to care. I see a huge cake on the table, a new scale on the floor, and an envelope pinned to the wall.
I know I’ve reached my goal and can’t wait to see ‘500’ on the scale, I just need to heave myself out of bed and waddle my huge fat naked ass across the room. But now I’m *barely* mobile, and what once would have been fast and easy turns into a sweaty ordeal of navigating the world in a very different body.

I finally make it, but now I’m starving again and can’t stop myself from shoving handfuls of cake into my food hole. In the midst of gorging, I notice the word “SURPRISE!!!” written in frosting, which is confusing. What surprise? I lick frosting off my fingers and open the envelope to read the card inside: “Dear fatboy, we thought you might appreciate a more accurate scale.”

I get on the scale, wait a moment, then step off to read the result. ‘615’. I stare in disbelief at the number, and weigh myself again. ‘615’. Was the previous scale defective, or did my helpers tamper with it? By the time I’m able to process my new reality of life at six hundred and fifteen pounds, I’m starting to get turned on. I look at my body in the mirror, and a combination of joy, excitement, admiration, and genuine contentment flows through my mind as I study every crease, dimple, fold, and roll. This is everything I wanted and more. A whole new world has opened up. And for the first time in a long time, I’m happy.

You’re welcome.
If I had the chance, I would love to grow to 350-400 lbs. I feel that’s a realistic goal for a very short guy. But the problem with goals is that when you achieve them, sometimes you think: “Now what do I do?” I often fantasize about what 500-600+ lbs. would be like, but for me those are just fantasies.

I cannot say for certain that I do or don’t regret gaining. Mostly I don’t because I love feeling fat and it’s (auto)erotic, but there are also times when I wish I was thin and fit again—like when I have to exert myself. I have a theory that gaining may be more challenging mentally for some who start thin, because we’re not accustomed to being “a fat person”, living as one, and being treated as one.

Being fat was a desire of mine since I was a teenager. I tried padding first, which was fun but ultimately unsatisfying, so I tried gaining on and off for years. My size fluctuated between “very skinny” (when I was addicted to opiates) and “a little bit chubby” when I tried gaining.
By the time I was 30, I couldn’t suppress my burning desire to become fat any longer. I decided to gain 100 lbs. I embraced the feedee/gainer lifestyle, avoiding exercise while eating as much as possible, and eventually I was successful in my goal—plus ~20 lbs. I went from a “normal” weight to “class III obesity”.
Right now I’m not really in a position to continue gaining (I would if I could), so I’m just maintaining, trying to enjoy myself around food, and occasionally overindulging my appetite.

I’m more mindless when eating, also food and calorie-obsessed. I’ve developed an autoerotic relationship with my body. Over time I changed from a more dominant feeder role to a submissive feedee. I’ve become habituated to overeating and avoiding exercise whenever possible.

I also genuinely perceive distances as farther than they actually are:
pubmed.ncbi.nlm.nih.gov/26854404/

I don’t have a great answer to your question but I’ll relay an anecdote.
My last job was at a small business I worked at for ~10 years. When I started, I wore a medium-sized shirt and was fairly thin. By the time I left I had (deliberately) ballooned up to a 3XL shirt, and was definitely not thin. No one said anything directly UNTIL one day when a coworker (woman in her 70s) asked me a math question and my answer happened to be: “450.” She came back with: “What is that, your GOAL WEIGHT??”
This was only the second experience in my entire life being fat-shamed so it’s not like I had some clever response prepared or defenses built up. (She also said this right in front of a client.) I just sort of laughed nervously, but on the inside I was surprised and hurt since I thought this lady was kind and not the type to stoop so low.
In hindsight I probably would’ve gone the full-on comedy route, turning it into a male pregnancy joke or whatnot.

Feedism certainly encompasses a spectrum. Where one identifies oneself on the spectrum can change. How one gets off sexually within it can change. The intensity and/or clarity of how strongly a person feels this is an inseparable part of who they are usually varies over time. (It might start off more casual or fantasy-based and turn into a lifestyle.) But generally speaking, it’s not something that goes away.

tl;dr
As a doctor, a scientist, and your attorney, I strongly advise you to eat 16 doughnuts a day. 😉

Personally, my fupa became pretty pronounced and fairly deep (enough to engulf most of me flaccid and some of me erect) after I gained about 100 lbs… but I’m very short plus I was looking to gain fat and not muscle so YMMV.