FAT IN EXERCISE
Dietary fat has been blamed for many health problems; however, fat is actually an essential nutrient for optimal health. Fat is stored when we consume more calories than we use. There is an optimal level of fat for health and for exercise. Carbohydrates and fat are the main sources of fuel for exercise. When that optimal level is exceeded, too much dietary fat can lead to problems with health as well as athletic performance,
FUNCTIONS OF FAT
Fats are similar to carbohydrates; they are important nutrient for athletes and non-athletes. It serves as a primary energy source at rest and during light moderate intensity exercise. Fat is often criticized especially among athletes and passionate exercisers who do worry about the negative impact that excess body fat may have on performance and training. But fats have important functions in the body.
- Fat can be oxidized to supply fuel for cells in the body – 1 g of fat gives off 9kcal or 38 kJ. It is the most energy dense nutrient compared to carbohydrates and protein which provide 17kJ or 4 kcal per gram.
- Fats provide essential fatty acids so it needs to be consumed in the diet
- Fat act as a carrier for fat soluble vitamins (A, D, E, K) and antioxidants around the body
- Fat insulate internal organs and the body by preventing heat loss.
- It provides the largest reserve of stored energy available for activity
- Adipose tissue is the protective layer for the organs
- Fats forms brain tissues and nerve cell membranes
- Fat is also needed for making hormones and prostaglandins
STRUCTURE OF FAT
Fat are also known as lipids. They can be obtained from both plant and animal sources in our diet. Triglycerides are the most common type of fat; 95% of dietary fat are triglycerides. Triglyceride is composed of 1 glycerol and 3 fatty acid molecules. Fatty acids can vary and they determine the nutritional properties and the physical characteristics of fats. There are 21 different fatty acids that exist in the diet, similar to the amino acids. Dietary fats come as cholesterol, phospholipids, sterols and carotenoids.
Fat is stored in adipose tissue and intra muscular tissues. A lean athlete with 12% body fat can store 70 000+ calories in their adipose tissue and intramuscular tissues can store 1 500 calories within muscle cells. So we can think how much more fat a sedentary person has in terms of calorie to use as energy. Fatty acids provide more ATP per molecules; however the body cannot burn fats as fast as carbohydrates.
ROLE OF FAT IN EXERCISE
There is no recommended daily amount set for total fat intake. So, focus is on hitting carbohydrate and protein targets. Then fat would make up the rest of the calorie balance. It is important to know that consumption of fat should not fall below 15% of total energy intake. Should our consumption fall below 15% of the total calorie intake the body will not be able to carry the essential functions that fat has in the body leading to health impairment. Restricting fat may impair performance. While these calories are less accessible to athletes performing quick, intense efforts like sprinting or weight lifting, fat is essential for longer, slower lower intensity and endurance exercise such as easy cycling and walking.
Fat provides the main fuel source for long duration, low to moderate intensity exercise (endurance sports such as marathons, and ultra-marathons). Even during high intensity exercise, wherecarbohydrate is the main fuel source, fat is needed to help access the stored carbohydrate (glycogen). Using fat for fuel for exercise, however, is dependent upon these important factors:
- Fat is slow to digest and be converted into a usable form of energy (it can take up to 6 hours).
- Converting stored body fat into energy takes time. The body needs to breakdown fat and transport it to the working muscles before it can be used as energy.
- Converting stored body fat into energy takes a great deal of oxygen, so exercise intensity must decrease for this process to occur.
For these reasons, athletes need to carefully time when they eat fat, how much they eat and the type of fat they eat. In general, it’s not a great idea to eat fat immediately before or during intense exercise.
Ten percent of your bodyweight in grams of fat should be considered the minimum daily consumption. Optimal intake will be closer to ten percent of total daily calories. One thing about fat is that there isn’t much of a drawback from overconsumption of the healthier options. Over consuming protein will wreak havoc on your kidneys. Too many carbohydrates in the diet could predispose you to insulin sensitivity and lead you to pre diabetic complications. As long as calories are maintained, more healthy fats don’t pose much of a problem. With that in mind, an increase in fat consumption should be considered when looking to gain mass. Always aim for a fat intake between 20-35% of total calories. On the other hand, fat – when trying to lose weight – can serve different purposes. Decreasing fat in your diet can help lose weight more easily, since fats have more than double the calories per gram than both protein and carbs. So keep to the lower end of the range rather than less than 20% which can impair the body from functioning well.
It is recommended that from the total calories coming from fat, 45% must come from unsaturated fats( mono-unsaturated and polyunsaturated fats sources), 35% from omega 3 sources and 20% from saturated fat sources (animal sources).
FAT: THE GOOD, THE BAD & THE UGLY
We have all heard that we should be eating “healthy” fats, but what does that mean? Almost all fats are healthy except for Trans fat, some needing to be consumed in greater quantities than others. Mono-unsaturated and polyunsaturated fats are considered healthy fats which help to increase HDL cholesterol and decrease the more unhealthy LDL cholesterol. Foods containing omega 3 and 6 fatty acids are considered essential since the body cannot make them from other nutrients. Saturated fats have health and body composition benefits, but it is common to overeat this type of fat and should be limited since it is also associated with health problems.
- Saturated fats are found primarily in animal sources like meat, egg yolks, yogurt, cheese, butter, milk. This type of fat is often solid at room temperature. Too much saturated fat has been linked to health problems such as high cholesterol and heart disease. Because of this, saturated fat should be limited to no more than 10% of total daily calorie intake.
- Unsaturated fats include mono-unsaturated and polyunsaturated fats, which are typically found in plant food sources and are usually liquid at room temperature. Unsaturated fats have health benefits such as lowering cholesterol and reducing the risk of heart disease. Common food sources include olive and canola oil, avocados, fish, almonds, soybeans, and flaxseed.
- Trans fat has recently been added to the nutrition labels of most products. Trans fatty acids are created (naturally or man-made) when an unsaturated fat is made into a solid. Trans fats, like saturated fat, should be limited because they increase cholesterol levels and the risk of heart disease.
Dietary fat is frequently undervalued as a contributor to health and performance of athletes. Fat is an extremely important fuel for endurance exercise, along with carbohydrate, and some fat intake is required for optimal health. In the next article we are going to discuss nutrient timing for exercise and it would be a better indication when to eat these nutrients for optimal benefits.
- Role of fat metabolism in exercise. Clinical Sports Med. https://www.ncbi.nlm.nih.gov/pubmed/6571234
- Dietary fat and performance. National Strength and Conditioning Association. https://www.nsca.com/education/articles/dietary_fat_and_performance/
- Aperspective on fat intake in athletes. J Am Coll Nutr. https://www.ncbi.nlm.nih.gov/pubmed/10872896.
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