this is issue so much more complex than you think. Let's take myself. I have had major spine surgery with massive complications. exercise is not a option here, or my wife who has a thyroid condition (she has lupis which seems to like her thyroid). So what about us. My view of fasting isn't to "not eat meat", but to eat as little as i can get away with. The idea is to try to suffer a little more in Christ in a diffrent way (in this case through food). Then there are the studies that no one talks about. It's better to be 20 lbs over weight than any under weight. You are actually less healthy when your underweight than being a little over weight. Then there is the human factor, what does weight have to do with who or what a person is? it doesn't. People are people, we are all diffrent, thankfully and to think that there is a magical body size is silly. I spent 5 years lifting weights before my back went south. i can tell you from experience, that nothing shocks people more than to find out that you weigh more than they do and you do not have anywhere near the same body size as they do (muscle weight is twice fat weight for the exact same amount. for example if i took one cup of muscle and weighed it, it would be twice as heavy as one cup of fat). My point here is that there are far more important things to worry about than how big someone is. Instead lets worry about praying enough each day, or following the fast for the right reasons, or even better, not deciding what is good for others when we can't even figure out what's good for ourselves.