Does microwaving food make it unhealthy? What the science says

For most people, no. The evidence does not support the idea that microwave cooking makes food inherently unhealthy. In some cases, it can actually be an efficient way to retain nutrients because cooking is rapid and uses little water. The healthier question is not “Was this food microwaved?” but “How was it cooked, what was added to it, and how long was it heated?”
A bowl of vegetables quickly microwaved with a little water can be nutritionally sound. A highly processed, salty ready meal heated in the same appliance does not become healthy simply because it came out of a microwave. The microwave, in other words, is neither a nutritional villain nor a health miracle. It is simply another cooking tool, and like any tool, what matters most is how you use it.