Hi all.

Comparing the nutritional value of a meal  with protein, carbohydrates, lipids, vitamins and all the rest together, that was cooked with a microwave oven and one equal cooked with a convection, conduction method for cooking;  should differ ?

Is there a study about such, away from speculations ?

Can different heat energy sources from radiant fire,  microwaves,  immersion in boiling,  even concentrated solar radiation cookers or any other,  alter nutrition or create more or less toxins  ?

 

To my knowledge microwaves do not do something fundamentally different to food than other heat sources. What is more important is the overall setup of the cooking method including temperature, length of heat exposure, presence of solvents into which nutrients can transition into (e.g. boiling or deep frying) and so on. A such, studies have shown that the loss of vitamins during microwaving is fairly similar to other cooking methods and may be superior to those where loss can be attributed to higher extraction efficiency (e.g. steam cooking). 

Many of the listed components are stable at temperatures much higher than used for regular cooking. There are a few heat labile vitamins, but carbohydrate and protein content generally does not change with most cooking methods. One thing to remember is that larger molecules, such as proteins, are not used as a whole, they have to be degraded to smaller bits and pieces before we can actually take them up (which is done by treatment with various enzymes detergents acids etc. in our digestion system). 

One reason why microwaved food has a bad rep is because food specifically designed for the microwave are often heavily processed and are made to be palatable just by heating it up. But they are rarely made to provide a balanced diet.