The fasting of food is great for our body, mind, and soul.
For special medical concerns, I'd ask a doctor.
There are so many other things that we can and should fast of too.
Like the TV and radio, even Christian programming. Just take a break and listen to the quiet we've missed. Take the time to read and pray.
The fasting of money is good too. Go for as long as you can without spending on anything and when you do break it, buy only food and bare essentials the first day.
I feel the fasting of anything brings appreciation for more than just what was fasted from. A gratefulness to God for everything comes about in one's life and whatever was a bother previously doesn't seem so important.