At the Wellness Club cooking classes, instructors teach a method of cooking and baking that requires absolutely no oil. I have to admit that the idea of stir-frying without using a drop of a oil sounded crazy to me when I joined. And then I learned a method called steam saute which uses a very hot pan to release steam from vegetables allowing you to stir-fry completely oil free. I learned that you can caramelize onions and garlic, releasing all the wonderful naturally occurring sugars that coat your food, and just add a bit of water or broth to de-glaze the pan. So why do they teach no-oil cooking?
The main reason to skip oil is that quite simply it is the _most_ calorie dense food that delivers almost zero nutrients relative to the calories. The key here is the ratio of nutrients to calories. We often hear about how certain oils, like olive oil, contain the "heart healthy fats" like omega 3 and 6. Well, that's partially true, but it comes with a delivery mechanism that is adding a huge amount of wasteful, zero-nutrient and heavily dense calories to your food. Furthermore, any potential benefit of the good fats is negated by unhealthy ration of the omega-6, when it comes to olive oil.
Olive oil is a mono-saturated fat, and the omega-3 to omega-6 ratio is so far off in one tablespoon, it actually negates any potential benefit. To boot, that one tablespoon also contains 120 calories and 14% saturated fat. (from mindbodygreen)
To use oil for the _potential_ benefits would be like eating an entire chocolate candy bar because there are high amounts of antioxidants in cacao. Skip the candy bar and eat the cocao! It's time that we dispel the myth that olive oil is a health food. If we look at oil for what it actually is, it is a processed fat additive. It's made by extracting the fat from a whole food. Why do that? Why not just eat the whole food? It boggles the mind that we take a good healthy fat, like a nut, and then roast it in oil. We get plenty of real "heart healthy" fats from plants like avocados, seeds and nuts -- but these whole food sources contain high ratio of nutrients to calories. It's all about the nutrients to calories ratio. Olive oil is a junk food and it's keeping us fat. Give up the oil! I'm not even going to get into the further health detriments of heating oil, but I feel like more people understand that heating oil past its smoke temperature actually creates dangerous chemicals.
The reality is that oils are extremely low in terms of nutritive value. They contain no fiber, no minerals and are 100% fat calories. And above all they contain saturated fat which immediately injures the endothelial lining of the arteries when eaten. It doesn't matter whether it's olive oil, corn oil, or any other kind of oil. (from a Q&A with Dr. Esselstyn)