I think of the change in terms of reason - what I learned, and what those lessons mean to me - but I suspect that's not what really happened. I've read that the way we make decisions is emotional; that we use reason to explain and justify the decision afterwards. If that's true, I can't explain why the emotional shift happened when it did. But the reasons are still interesting.
First, why don't I want to be fat? A lot of the pressure to be thin in our culture comes in two forms: thin is beautiful, and thin is healthy.
The first (this is beautiful) is arbitrary - our ideas about what is beautiful change all the time. Fatness has been highly admired at times, when it demonstrated a person's ability to access to otherwise scarce food, for example. Furthermore, today's ideals of beauty are so extreme as to be absurd, and highly motivated by the conventional advertising strategy of making people hate themselves. I can reject that.
The second (thin is healthy) is not very reliable. Extremely thin people are often unhealthy, but they are often presented as an ideal. People restricting their diets to become thin often eat in unhealthy ways (I hear lots of stories of vegans getting sick, for example). Furthermore, I wonder if we are confused about causes. Causality is very difficult to get right. Consider this text from Wikipedia:
Obesity increases the likelihood of various diseases, particularly heart disease...
So, you look at a sample of people who have heart disease, and how many are obese. You compare that to obesity data from the general population. You find that heart disease patients have higher obesity rates. Or you do it the other way: look at a sample of people who are obese, and see how many have heart disease. Whatever. But you can point at your data and see that heart disease and obesity appear together (correlation) but you don't know why (causality). Here are some possible causal relationships:
- Excess body fat strains the heart, causing heart disease.
- The kinds of lifestyles that produce excess body fat (e.g. stressful office work) also cause heart disease.
- The kinds of diets that produce excess body fat (e.g. sugars) also cause heart disease.
- Some genes that cause fat accumulation also cause heart disease.
- Certain environmental factors (e.g. exposure to toxins) trigger both.
- Fat people receive a lot of criticism, producing a negative self-image, which causes heart disease.
- A negative self-image triggers both heart disease and eating habits that make you fat.
- The experience of early stages of heart disease causes a low level of discomfort that triggers eating as a distraction.
- Fat people are more likely to diet. Somehow dieting causes heart disease. Perhaps the foods we crave are exactly the foods that prevent heart disease, and dieters deny themselves the foods they crave. Perhaps self-denial is a direct cause of heart disease. etc.
Of course, this is all speculation on my part. Maybe lots of medical scientists have studied the problem deeply enough to be certain that being fat causes heart disease, and that losing that fat (by any means) would reduce heart disease. I'm not done, though.
Aside: doctors tell us to lose weight by exercising more (even though the science says this doesn't work, because it increases appetite to match) and by eating less (even though the science says this doesn't work, because the body can prioritize fat storage over other uses of calories, even when the calories are scarce). Gary Taubes presents the science on this pretty well, and concludes that carbs cause weight gain or loss. He doesn't dig in to questions like "why do I crave carbs?". I suspect you need to answer that question, and the Why? behind it, and maybe a couple levels below that, before you can really get somewhere useful.
Anyway, losing weight is hard. Ask anyone who has tried. Even if you succeed, keeping it off is extremely difficult. People who lose weight usually gain it back not too long afterwards. I recently read a claim that there is no method scientifically proven to work at losing weight and keeping it off. If this is true, then it doesn't matter if being fat is unhealthy, or being fat is ugly - you can't change it anyway. In the meantime, you beat yourself up, deny your urges, create personal stress, etc., with no chance of success. Better to just accept that you're stuck here (for whatever reason), and get on with enjoying life.
Getting a little more radical, perhaps there's a very good reason for me to be fat. I don't know what it is, but I can acknowledge the possibility of some body wisdom that guides me towards fatness. Maybe fat is the healthiest way for me to be right now. If that is true, then ice cream cravings aren't the cause of my obesity, merely the mechanism by which my body guides me to foods that help it accomplish this important purpose of being fat. (Or perhaps cookies heal something in me, and fat is just an unfortunate side-effect.) To fight those urges is to wage a war against myself, producing great harm.
Anyway, why are we so certain that we must be healthy and beautiful? Where is it written? The inherent worth and dignity of every human being is not dependent on those things. They are temporary anyway.
With all this in mind, I've decided to let myself be fat. If I crave pudding, I will eat pudding. There's nothing to be gained by fighting these urges, and all kinds of possible gain by following them.
Now that I've had this change of heart, I have discovered some other things I I like about myself as I am. First, I am very strong. Consider the stories of soldiers in boot camp, made to carry a 50lb pack for hours on end. I weigh 100lbs more than those guys, and I carry that all day, every day. Quit your wining, grunt!
A couple years ago I took a rock climbing class. There was one other student, who was in "good shape". He climbed the wall much faster than I did. Fine. Maybe I could have climbed a little with him on my back; no way he could have done that with me on his back. So there!
The strength is not just physical: I still live a rich, varied, and wonderful life in this body. How many skinnies would sink in to helpless despair if they put on this much weight, and were criticized so strongly by our culture?
So here I am. Fat, and not going anywhere. For better or worse - and I choose for better.