Fats 101
With an energy yield of 9 calories per gram, dietary fat, or fatty acids, is a major source of energy in the endurance athlete diet. The energy molecules in the fat called triglycerides constitute the majority of the fat you consume in your diet. Cholesterol, or lipids, makes up the remainder and are more involved in building and maintaining healthy cells. Despite the hysteria in recent years dietary fat is essential for good health. Fat provides energy, insulation and padding for our bones and internal organs and contribute to a strong immune system.
While carbohydrate provides the energy for efforts above 70% of V02 max fatty acids contribute the energy for your activities up to about 50% of your V02 max. As the intensity of your riding increases the percentage of calories provided by fatty acids decreases rapidly. However, even at intensities of 90-100% of V02 max you are still using fatty acids in the energy chain.
Once eaten, fats are digested into their primary components, fatty acids and absorbed into the blood stream for distribution throughout the body. Fatty acids are either immediately metabolized for use as energy by different cells or converted back into triglycerides for storage and later use, much the same as excess carbohydrates. Fats cannot replace carbohydrate during recovery to replenish glycogen stores because they do not stimulate the release of insulin to assist in carbohydrate metabolism and muscle glycogen uptake.
It is not only a good idea to limit your intake of fatty acids to a healthy and necessary level but you also need to make sure they are coming from the best sources. Certain dietary fats are healthier than others in terms of their effect on blood cholesterol.
Total blood cholesterol includes two main sub-types: LDL (low-density lipoprotein) cholesterol and HDL (high-density lipoprotein) cholesterol. LDL is the “bad” cholesterol since can lead to harmful fatty deposits on the walls or your arteries causing restricted blood flow and life threatening cardiovascular stress. In contrast, HDL is a much friendlier form of dietary fat and does not contribute to cholesterol build up in the arteries. The “ratio” of LDL cholesterol to HDL cholesterol in the diet is considered to be more important than “total” blood cholesterol alone.
There are 5 different types of dietary fat to consider.
Saturated fat is most common fat in the diet of industrialized nations. It tends to be solid at room temperature, and is found in animal-based foods like meat, poultry and processed meat products, as well as milk and dairy products. Vegetable sources of saturated fats include coconut and palm oil, cocoa butter and chocolate. All forms for saturated fat contribute to increased LDL levels but not all at the same rate. The type of saturated fat in butter, for example, strongly increases LDL levels while beef fat increases LDL levels to a lesser degree and cocoa butter fat increases LDL levels even less.
Mono-unsaturated fat is commonly found in vegetable oils like olive, canola and peanut. These fats are basically cholesterol neutral because they do not seem to raise either LDL or HDL cholesterol levels when taken into the diet at healthy levels. Increasing Mono-unsaturated fats in your diet will replace saturated fats with a healthier alternative.
Poly-unsaturated fats are found in vegetable oils such as soybean, cottonseed, corn, sunflower, and safflower and go a step further in the fight against LDL cholesterol. They not only replace fats containing LDL cholesterol they also increase the HDL levels in the blood.
Essential fatty acids, or EFAs cannot be produced in the body and have to be obtained from your diet. EFAs help your body with cell production and growth, and other metabolic processes and help maintain healthy brain and nervous system function. There are two EFAs, omega-3 and omega-6 that your body needs to maintain good health. Sources of Omega-3 include fish oils, and vegetable oils like canola, flaxseed and walnut. Sources for Omega-6 include more common nuts, seeds and legumes and unsaturated oils like sesame, and soybean.
Trans fatty acids are the result of a hardening process called hydrogenation that is used to solidify mono- and poly-unsaturated vegetable oils to produce margarine. These margarines meet the market demand for a non-butter spread but the result is a product that has a similar effect on LDL and HDL cholesterol as saturated fat. Spreads high in trans fatty acids actually raise LDL levels while lowering HDL levels. Trans fatty acids are Double Trouble.
Dietary fat is important to your health and performance for many reasons. Fatty acids are the most concentrated source of energy in your diet and an important energy source for low to moderate intensity exercise. With additional development of the aerobic energy system this dependence can be increased to spare limited glycogen stores.
Fats are important structural components of cell membranes and are vital to a healthy immune system. Getting the right balance of fats is important. You should avoid saturated fats as much as possible and substitute them with mono- and poly-unsaturated fats whenever possible. Try to keep your total fat intake at about 20-25% of your total daily calories. There are so many sources of dietary fat available it should be easy to make good choices. All you need to do is read labels and do a little simple math.