I had a friend mention to me that her naturopath recommended against microwaving food because it would lose more nutrition than other forms of cooking. I was skeptical so I checked in with the Oracle (google) and here's what I found:
Heat is the main culprit that is definitely implicated in the loss of nutritional value of food. The argument is turned around based on this fact and microwaving might be beneficial in the nutritional sense because it takes less time to cook.The New York Times article specifies some instances in which the evidence shows this to be true.
Another culprit is water. The New York Times article further points out how cooking vegetables in water takes out nutrients.
The CNN article goes into the details of various ways to rob your food of nutrients.
But microwaves were always found not guilty of robbing nutrition from food.
New York Times
Harvard Medical School Family Health Guide