What kinds of fats are there?
Understanding which types of fats you are choosing and adjusting the ratio of fats you are eating in a Keto lifestyle is crucial.
Trans fats can be found in many foods — including fried foods like doughnuts and baked goods including cakes, pie crusts, biscuits, frozen pizza, cookies, crackers, stick margarines and other spreads, the totally "plastic" whipped toppings, Crisco, and hundreds of processed food products. These are the fats that contribute to heart disease, obesity, diabetes, inflammation, IBS and other diseases. You can determine the amount of trans fats in a particular packaged food by looking at the nutrition panel. Do not be fooled and don’t fool yourself: Products can be listed as "0 grams of trans fats" if they contain 0 grams to less than 0.5 grams of trans fat per serving. You will be able to spot trans fats by reading ingredient lists and looking for the ingredients referred to as "partially hydrogenated oils."
Polyunsaturated Fatty Acids (PUFA) can be dangerous for several reasons. Because of their structure, they are chemically unstable and susceptible to damage from heat, light and oxygen, causing them to oxidize thus causing high levels of inflammation in our bodies. These are mostly the industrial oils such as corn oil, peanut oil, "vegetable" oil, soybean oil and canola oil. However, many fats have naturally occurring PUFAs but will be identified as its main source of fat. Bacon is 11% PUFA, but identified as a saturated fat. There is no need to include PUFAs in your diet intentionally by using corn oil for frying, for instance.
Monounsaturated Fatty Acids (MUFA) are found in olives and avocados and their oils and nuts such as hazelnuts (or filberts), macadamia nuts, pecans, almonds, pistachios and cashews. Be aware that especially with nuts you have to count other categories that are in the food: carbohydrates and protein. In this regard, be especially careful of cashews on Keto — they are actually not a nut but rather a seed and they have a very high carbohydrate content: 27 carbs per serving as opposed to Macademia nuts that have 5 carbohydrates per serving. Peanuts are allowed on Keto even though they are a legume and not a nut, and they are very rich in monounsaturated fats. (Just an FYI here: Valencia peanuts and peanut butter are preferred because the chance of fungus is less.) Sesame seeds and sesame seed butter (tahini) are high in monounsaturated fatty acids as well. Lesser sources (but still good) are sunflower seeds and sunflower seed butter, pumpkin seeds and flaxseeds.
Saturated Fatty Acids are mostly found in animal fats but can also be found in some plant foods such as coconut oil and coconut butter. They are in all meats but especially fatty meat such as beef brisket and cuts such as rib eye and prime rib, and bacon, and fatty fish such as salmon, mackerel, and sardines, duck, various cuts of lamb and pork, and deli meats such as Mortadella and salami. Other great sources are full-fat dairy such as butter and heavy (whipping) cream. Other SFAs are coconut and palm oils, ghee, lard, tallow, and other fats from animals that are good for cooking such as duck fat, lamb fat and chicken fat.
As the above example with bacon having naturally occurring PUFAs, many other fats are a combination of MUFAs, PUFAs and SFAs but are identified in one category or another according to the highest percentage of which fat it has. For example, coconut oil is 87% saturated so it is identified as a saturated fat even though 13% is not saturated. Whether or not you eat fats that are themselves combined (and no one would expect you to do this research!), you should aim for a good degree of variety between the MUFAs and SFAs.
Omega Fatty Acid
Omega fatty acids are from a family of fats that commonly are found in vegetable and animal fats. The number of the omega (we have all heard of Omega-3 and Omega-6 and the less common Omega-9) comes from its position on the fatty acid chain (alpha being the front of the chain and omega being the end). For instance Omega-3 has its double bond between the third and fourth link, and the Omega-9 has its double bond in the 9th position. You may have also heard of EPA and DHA (or have seen them on supplement bottles), and they stand for eicosapentaenoic acid and docosahexaenoic acid, respectively. These fatty acids are Omega-3 fats.
Understand the balance of fats you're eating
More than you wanted to know but here is what you do want to know: If it is an essential fatty acid it means we need to get it from our food. If it is a non-essential fatty acid our body can make what it needs. We should work to balance the 3 and 6 omegas, for maximum health. Not only do we tend to be deficient in Omega 3s but we tend to have an over-consumption of Omega 6. There are both Omega 3 and Omega 6 in PUFAs, but the ratio of 3 to 6 is top heavy on the 6. This imbalance, especially if you do not consume healthy fats, causes inflammation, poor gut health, and contributes to IBS (inflammatory bowel disease), heart disease, diabetes and liver disease. However, it is not enough to eat pounds of salmon or take Omega-3 supplements to balance out this ratio. The thing to do is to eat less PUFAs thereby lessening the load of Omega 6 in your body.