GOOD VS BAD FATS
The terms “good fat” and “bad fat” are thrown around daily in the fitness industry, often without justification or any practical recommendations. In this post, I’ll try to shed some light on what these terms mean.
What makes fats good or bad?
Although the terms are quite subjective, most scientists agree that they refer to the effects of different types of fat on cholesterol in the bloodstream, specifically, on lipoproteins (the cholesterol carriers). High - density lipoprotein ( HDL) and low -density lipoprotein (LDL) are the two main classifications of plasma lipoprotein particles, and are nicknamed “good” and “bad” cholesterol, respectively; the latter due to their potentially atherogenic properties (i.e., their ability to cause plaque buildup in the arteries). While high levels of LDL are not necessarily bad, in general, the distinction between “good” and “bad” cholesterol is a valid one—further distinctions are beyond the scope of this post.
The Basics of Dietary Fats
Dietary fats (technically triglycerides) are made up of one molecule of glycerol (a sugar) and three molecules of fatty acids. Their effects on health and metabolism depend primarily on their structure. Triglycerides can differ in size, short-, medium-, or long-chain (depending on the number of carbons present) and by the number of double bonds. There are four main types of dietary fats/triglycerides:
Trans fat
Man-made trans fats, also known as partially hydrogenated vegetable oils, are found primarily in margarine and junk food to give them a longer shelf life. These fats tend to increase LDL and reduce HDL, and their negative effects on cardiovascular health mean they should be avoided. Fortunately, many fast food restaurants and supermarket chains have significantly reduced or eliminated the use of these types of fats in their foods.
Saturated fats
The type of fat most people are familiar with, saturated fats are solid at room temperature, have no double bonds, and occur predominantly in animal foods such as meat, eggs, and dairy products. The hysteria surrounding saturated fats has died down since the 1980s, as sugars have become the subject of demonization. While there are many types of saturated fats, they tend to increase both HDL (good) and LDL (bad) cholesterol. Since the ratio of HDL to LDL is more important than the amount of either, saturated fats are pretty neutral when it comes to health in most cases. That said, in small doses saturated fats are not atherogenic (i.e., they do not promote plaque formation in the arteries), but in larger doses, particularly palmitic acid (commonly found in butter), they can dramatically increase the risk of developing atherosclerosis.
Monounsaturated fats
Monounsaturated fats are liquid at room temperature, have one double bond, and occur predominantly in foods such as olive oil, nuts , and seeds. In terms of health, they range from neutral to beneficial, as they tend to reduce LDL levels in the bloodstream. Therefore, this type of fat should make up the bulk of your fat intake.
Polyunsaturated fats
Polyunsaturated fats are also liquid at room temperature and have multiple double bonds. The two primary classes of these fats are omega-3 and omega-6 essential fatty acids. While omega-6 fatty acids can be found in many animal and plant foods and are relatively neutral to health, omega-3 fatty acids are found predominantly in fish and some plants (such as flaxseed) and have virtually every health benefit imaginable.
Final message
- Consume most of your fats from monounsaturated sources, with the remainder divided into saturated and polyunsaturated; with as little as possible coming from trans fats;
- Although the amount and type of fat consumed daily is certainly a fundamental factor in optimizing health, it is important to emphasize that other aspects of diet and lifestyle can be much more relevant.