I know a lot of people who have gone without food, or eaten very little food for one reason or another, over protracted periods of time, including myself. In some cases it was weight loss or “cleansing” related, in some cases it was religiously motivated (including non-Catholic or non-Christian religions), in some cases it was due to lack of food money, or simply being so overwhelmed with life responsibilities or tragedies that they did not have motivation to eat very much.
We’ll leave out the people who developed full-blown or borderline eating disorders, since you pooh-poohed that. It’s a serious problem, whether you want to see it as such or not. I developed some very unhealthy eating patterns, but did not have a disorder and have never been below a normal weight range. I mention that just so nobody thinks I’m pushing an agenda. I knew plenty of other anorexics and bulimics though. They keep it very well hidden.
Some people who limited their food had fainting spells. In some cases this resulted in injury. I myself have passed out once in the past and come pretty close to it several more times. I discovered at some point I had anemia which I hadn’t known I had. A couple other people I know also discovered they had anemia or diabetes.
If you are limiting your food while you are a) driving, b) taking care of children, or c) operating machinery at work, bad things can obviously happen. You may say this sounds like common sense, but you often feel pretty OK right up to the point 30 seconds before you pass out when you don’t feel okay any more. And needless to say, I don’t want any doctors or medical staff taking care of me or my loved ones fasting while they are on the job. All it takes is one mistake caused by lack of focus…
Going without food for prolonged periods can also have mental health effects. A lot of my anxiety and mood swings turned out to be caused by blood sugar imbalances caused by not eating. As it turned out, I did not need professional help, I needed to eat a healthy dinner.
There are endless studies about how young people don’t learn very well in school when they are hungry, so fasting while you’re attending school or college is not a great idea.
After some years of an extremely limited food intake, I ended up having to go see a nutritionist for a while to basically get trained on how to properly eat.
I’m sure there will be people coming out of the woodwork now saying they never had any problems while fasting and it’s just the greatest thing ever for them and their spiritual life. The problem is when you start suggesting that all people should do it, you run into a significant percentage who have some or all of the above problems. I think this is one reason why the Church doesn’t really push the idea of fasting. To say nothing of the fact that the Church is concerned with feeding the hungry and doesn’t really want to put hunger up on a pedestal as a wonderful thing.