Energy in the diet comes in three forms – carbohydrate, protein and fat. These macronutrients are organic compounds of carbon, hydrogen and oxygen, but in different ratios. There are three main types of fats in the diet: saturated, mono-unsaturated (MUFAs) and poly-unsaturated fatty acids (PUFAs). Other types of fats in our foods include trans fatty acids and cholesterol. There is so much controversy about including fats in our diet, that it is essential to understand the essential role that healthy fats play.
- Energy: The main function of fat is to supply the body with fuel. This energy is stored in adipose tissue and can supply fuel for many days if need be.
- Insulation: Fat stored in adipose tissue is largely stored subcutaneously (under the skin) which makes it an effective insulator and helps conserve body temperature in cold weather.
- Padding: Adipose tissue surrounding the vital organs like the kidneys, protects against physical injury.
- Hormonal and cell membrane function: If your body fat percentage drops too low, cell membranes and some hormones don’t function properly for example, oestrogen.
- Nerve conduction: Each fast-conducting nerve fibre is sheathed in a specific kind of fat called myelin.
- Fat soluble vitamins and essential fatty acids: The fat in our foods should contain fat-soluble vitamins A, D, E and K and the two essential fatty acids, omega 3 and 6.
DANGER! HIGH FAT WARNING
Fats and oils are part of a healthy diet. However, the types of fat and the total amounts of fat consumed are also important. High intake of saturated fats, trans fats and cholesterol increases the risk of unhealthy blood lipid levels, which may increase the risk of coronary heart disease. A high intake of fat (>35% of total calories) makes it mare difficult to avoid taking in excess calories, which can lead to undesirable body fat gain. A low intake of fat (<20% of total calories) may lead to unfavourable changes in high-density lipoprotein (HDL) blood cholesterol and triglycerides, increasing the risk of coronary heart disease.
GOOD FATS VS. BAD FATS
Certain fats positively affect your health and cholesterol levels, while others have a negative influence.
- Saturated fats, found in animal products such as butter and cheese, as well as in some vegetable oils, have gained the reputation of increasing bad cholesterol in the blood.
- Cholesterol is obtained mainly from red meat and shellfish. Red meat contains not only cholesterol, but also saturated fat. However, most of our blood cholesterol comes not from dietary sources, but from our livers. Our liver uses saturated fat to make new cholesterol. Thus, when you are told to lower your blood cholesterol, it is important that you watch the amount of cholesterol you eat and the amount of saturated fat you take in. This limits the amount of cholesterol the liver makes. The recommended amount of cholesterol should not exceed 300mg per day.
- Trans fatty acids are formed as a result of processing a fat in food manufacturing. Many of the fats used in food processing (such as those from nuts, seeds and beans) are liquid at room temperature and unsuitable for addition to foods. However, these oils may be treated chemically to make them solid through ‘hydrogenation’. During this process, fats are heated to high temperatures and hydrogen is added. This makes the fats more solid and also gives them a longer shelf life. However, it also damages fats and may lead to their conversion to unusually shaped fats known as ‘trans fatty acids’ or ‘trans fats’. Trans fats are found in a wide range of foods including commercially baked goods (biscuits, cookies, etc), fast foods, processed foods and margarines. The greater the degree of hydrogenation, the more saturated the fat becomes and the more trans fats are produced. These can cause more arteriosclerosis (fatty acid build up in the arteries) because they raise the LDL, or bad, cholesterol and lower HDL, or good, cholesterol. They have even been found to increase triglyceride levels (another type of dangerous fat that can damage the pancreas and lead to diabetes).
Unsaturated fats (PUFAs and MUFAs) are beneficial to us and may help lower cholesterol, provided they are eaten in moderation and replace saturated and trans fat in the diet.
- Poly-unsaturated fats (PUFAs) are found in two main types in the diet: omega 3 and omega 6 fatty acids. These play important roles in maintaining the health of the body’s systems and structures. The effects of PUFAs on the body are a result of their conversion into hormone-like substances known as eicosanoids, however eicosanoids derived from omega 3 tend to be different to those derived from omega 6. Omega 6 eicosanoids encourage inflammation, blood vessel constriction and clotting of the blood, while omega 3 eicosanoids have the opposite effect, that is, anti-inflammatory effects, reducing the risk of blood clotting. Because of this antagonistic relationship, it is important to consume these in the ratio (omega 6: omega 3) of between 5:1 and 10:1. Skewed intake of omega 6 can contribute to illnesses such as inflammatory disease (e.g. arthritis, gout), thrombosis (blood clots) and a compromised immune system. Unfortunately, the typical South African diet has far more omega 6 fats and not enough omega 3 fats.
- Mono-unsaturated fats (MUFAs) are believed to have benefits for the body. Including MUFAs in your diet, especially when replacing saturated and trans fats, lowers bad cholesterol and doesn’t lower good cholesterol levels. For this reason, they are considered to be cardio-protective.
HOW MUCH IS ENOUGH FOR MODERN ATHLETES?
Fat is a necessary component of an athlete’s diet as it provides energy, especially for long term endurance.
Fat also provides essential elements for cell membranes and is associated with nutrients such as vitamin A, D, E and K, and essential fatty acids. General recommendations for fat are 20-30% of total calories per day, with the fatty acid proportions being 10% saturated fat, 10% MUFAs, 10% PUFAs. The daily diet must include sources of essential fatty acids (omega 6 and omega 3). Most fats should come from MUFAs such as oils from canola, olive, peanut and avocado. Nuts such as peanuts and almonds, as well as peanut butter, avocado, olives and hummus are all high in MUFAs. Keep saturated fat and cholesterol to a minimum, so opt for fat free or low fat dairy products, lean meat, skinless chicken and fish. Lastly, avoid trans fats as much as possible, such as those found in fried goods and commercially-made food.
FAT REDUCTION TIPS
- Use extra lean meat where possible.
- Cut off visible fat before cooking, not after, as fat seeps into the flesh while cooking.
- Halve the amount of red meat you would normally use by adding legumes such as lentils.
- Choose no oil varieties of canned fish (e.g. fish in brine).
- If labelled, choose meats with 10% fat or less.
- Avoid processed meats such as sausages, wors and luncheon meats such as polony and salami.
- Boil, steam, bake, grill, microwave or ‘dry fry’ food, rather than frying.
- Cook roasts in an oven roast bag and remove excess skin or fat before roasting.
- Eat fish (especially oily fish such as salmon, herring or fresh tuna) at least twice a week.
- Limit red meat to two to three times a week and avoid other high cholesterol foods such as organ meats, caviar, prawns or calamari.
Dessert and sweets
Snack foods and take-aways
- Stay away from snack foods such as chips, vetkoek, dried wors and salted nuts. They are high in fat and we tend to over eat them.
- Make your own low fat snacks like air-popped popcorn, toasted pita strips, vegetables cut into small bite-sized snacks or roasted, curried chickpeas.
- Use hummus or avocado mixed with cottage cheese and lemon juice as healthy dips instead of high fat cheese dips or pat?s.
- Use avocado or hummus as spreads instead of butter or hard brick margarines.
- Limit take-aways and opt for healthier choices such as grilled chicken. Choose salad, vegetables, rice or baked potato instead of chips and onion rings. Share pizza and salad, instead of eating a whole pizza.
- The Completer South African Guild to Sports Nutrition by Louise Burke , 1998.
- American College of Sports Medicine. American Dietetic Association, Dieticians of Canada: nutrition and athletic performance. Joint Position Statement. 2009
- Delport L and Volschenk P (2007): Eat Smart for Sport. Tafelberg
- Dippenaar N and Delport L (2006): The South African Fat and Protein Guild. GIFSA