In general, fats are poor foods that should be avoided. Their ratio of nutrition to calories is absolutely the worst of all food types, except perhaps for pure white sugar, which is all calories and absolutely no nutrition (this is also true for other forms of sugar. Honey, too, contains almost no nutrition.). Gram for gram, fats contain many more calories than do sugars or starches. Yet gram for gram, fats contain virtually no nutrition except for small quantities of essential fatty acids. The perverse reason people like to eat fats is that they are very hard to digest and greatly slow the digestive action of the stomach. Another way of saying that is that they have a very high satiety value. Fats make a person feel full for a long time because their presence in the stomach makes it churn and churn and churn. Fats coat proteins and starches and delay their digestion, often causing them to begin fermenting (starches) or putrefying (proteins) in the digestive tract. The best fats contain high levels of monosaturated vegetable oils that have never been exposed to heat or chemicals--like virgin olive oil. Use small quantities of olive oil for salad dressing. Monosaturated fats also have far less tendency to go rancid than any other type. Vegetable oils with high proportions of unsaturated fats, the kind that all the authorities push because they contain no cholesterol, go rancid rapidly upon very brief exposure to air. The danger here is that rancidity in vegetable oil is virtually unnoticeable. Rancid animal fat on the other hand, smells "off." Eating rancid oil is a sure-fire way to accelerate aging, invite degenerative conditions in general, and enhance the likelihood of cancer. I recommend that you use only high-quality virgin olive oil, the only generally-available fat that is largely monosaturated. (Pearson and Shaw, 1983) When you buy vegetable oil, even olive oil, get small bottles so you use them up before the oil has much time being exposed to air (as you use the oil air fills the bottle) or, if you buy olive oil in a large can to save money, immediately upon opening it, transfer the oil to pint jars filled to the very brim to exclude virtually all air, and seal the jars securely. In either case, keep now-opened, in-use small bottles of oil in the refrigerator because rancidity is simply the combination of oil with oxygen from the air and this chemical reaction is accelerated at warmer temperatures and slowed greatly at cold ones.