If you fast on grass fed raw milk assuming it's fresh, it's fine in moderation, and if it's even processed a little it won't hurt you nearly as bad as many other foods out there, such as heavily processed foods or grains, after all it's a raw animal food, but it's still not balanced nutritionally at all, and there are far better animal foods, like raw beef, or for hydration - raw fruit juice, which are better at their specific roles.
People can be cured of "incurable" diseases just by fasting, breathing correctly, etc. It's simply doing something better than you were before. For example, if when people go up in spaceships, they suddenly became healthier, a logical person doesn't assume that outerspace is healing, but rather that their lifestyle radically changed.
So, when you fast on nothing but raw milk, the major change here is that you aren't eating all of the worse foods you were before, not that raw milk is balanced or magically healing in any way.
Of course, to simple minded common folk, the idea that people are cured while fasting on raw milk or using pyramid crystals is undeniable proof that those diets or methods are absolutely correct. These people need to read books on logic and deduction, rather than debate with other humans.