Learning about oils & fats is quite a process. There is much to know. Fats and oils are made up of carbon chains but are compact and simple. A fat chain is a linear arrangement of carbon atoms. Fats have hydrogen added to them making them hydrocarbons structurally related to petroleum. Each carbon atoms is able to attach 4 other atoms. When all of these spaces are filled the fat is saturated. When spaces are left open the oil or fat is unsaturated. Saturation determines the melting point of fat so the greater number of open spaces the more likely it is to be a liquid. Oils are present in many grains,vegatables and some fruits. As long as they remain part of the whole food they can be healthful but once removed they are subject to a host of destructive practices. When unsaturated the carbon chains of fats & oils can have open spaces filled with oxygen instead of hydrogen atoms. When oil is heated this process takes place rapidly. Rancidity results. Oxygen atoms are not tightly held and are very reactive. Free radicals are the compounds that hold them. The reactive oxygen will oxidize or burn other molecules like vitamins. Overheating changes fats altering thier molecules. These molecules are less useful and the body handles them differently. They are now potentially harmful. Heating oils between 375 & 400 F is bad news. Most vegatable oils are heat processed. Some oils are cold pressed like olive,peanut and coconut oils meaning these oils contain fewer impurities. Antioxidants are needed in people containing large amounts of polyunsaturated oils to scavenge for free radicals. There is a lot more to know in this arena for instance some oils are not good for cooking like flax but some can take the heat like grapeseed.
Also intersting is Honey. Honey is mostly fructose and glucose. It contains various sugars from the nectar of the flower it was taken from. It is absorbed relatively slowly probably b/c of its high fructose content.. It is delicate and easily damaged when heated. Heating should be avoided. Raw or uncooked honey is what we should be looking for. Cooked refined honey is what is sold in most grocery stores. Honey is refined b/c certain flowers produce a strong dark honey that many people do not like so it is cooked and filtered to remove these things and the result is an acid off flavor that is significantly different from raw honey.
I get this information from a book called Diet & Nutrition a holistic approac by Rudolph Ballentine, M.D.