Fat is an important nutrient that has received a bad reputation in the past years. The bottom line is that fat consumed in the right form and amount is a required nutrient for optimal health and physical performance.
The human body is dependent on fat for optimal health. Fat, or adipose tissue, functions as an insulator to preserve body heat and protect organs in the body. Fat-soluble vitamins A, D, E, and K, are dependent on fat for absorption and transportation in the body. Thus, individuals who eliminate fat in the diet with the understanding that they are 'being healthy' cannot absorb these vitamins and develop deficiencies, and may compromise the absorption and utilization of other nutrients dependent on fat in the diet.
Fat is found under the skin as an insulator, inside and between muscles, in cell membranes, and surrounding organs for protection. The primary function of fat is as an energy reserve for daily activities. Fat also plays a role in signal transduction between cells and certain fats serve as precursors for many important compounds in the body. One of these compounds, cholesterol, plays an important role for cell membrane structure and as a precursor for vitamin D.
Fat is stored as a result of excessive calorie consumption, which may be excessive protein, carbohydrate or fat consumption. For a healthy male the total percent of stored body fat is 10-20% and for females 20-30%. Athletes may have slightly less body fat than the typical healthy male or female.
Fat provides the largest energy reserve in the body. For a person weighing 70 kilograms (154 pounds) approximately 9 kilograms (19.8 pounds) can be stored in the body. This represents about 80,000 kcal. One pound of stored fat or adipose represents approximately 4,000 kcal.
Fat intake should contribute no more than 35% of the total daily caloric intake to promote health and well-being. Eat lower fat foods more often to keep your fat intake at appropriate levels. Athletes are encouraged to consume the bulk of their calories in the form of carbohydrate (55-60% of kcal) with moderate amounts of protein (15% of kcal) and fat (25-30% of kcal). The chart below shows the recommended grams of fat intake at various caloric levels and contribution (20%, 25%, 30%, and 35%) to total caloric intake.
Grams of fat in the diet
|Calories needed per day||20% fat||25% fat||30% fat||35% fat|
Food contains different types of fat, which have different effects on an individual's health status. Dietary fat can be divided into two groups: saturated and unsaturated. Know your fats in order to consume more of those that benefit your health.
Saturated fats are usually solid at room temperature, with the exception of palm oil, and originate primarily from animal sources, such as butter, milk, yogurt, cheese, mayonnaise, salad dressings, and meat. However, even some plant sources including palm and coconut oil, as well as hydrogenated oils found in chips, baked products, and snack items contain saturated fat.
Saturated fats should be consumed in moderation (no more than 10% of total caloric intake per day) because high intake of saturated fat increases blood cholesterol levels. Elevated blood cholesterol can cause blockage in the arteries and lead to heart disease. High intake of saturated fat has also been correlated with certain types of cancers, including colon cancer, and stroke.
Unsaturated fats can be further divided into monounsaturated, and polyunsaturated fats. These fats usually come from plant sources and are liquid at room temperature. Food items containing unsaturated fats include vegetables oils, olive oil, avocado, seeds, nuts, soybeans, fish, and flaxseed, among others.
Unsaturated fats have shown to provide many health benefits for the heart, including lowering harmful cholesterol levels. Some of these healthy unsaturated fats cannot be produced in the body and must be consumed in the diet.
In addition to saturated and unsaturated fats, a third group of fat is getting more attention, namely trans fatty acids. Trans fatty acids can be naturally occurring or produced from unsaturated fats. When the structure of unsaturated fats is changed making it solid in character, trans fatty acids are formed. Trans fatty acids are commonly found in margarine and in processed foods. Trans fatty acids like saturated fat, increases cholesterol levels, which can increase your risk of heart disease. Recently, trans fat was added to the Nutrition Facts panel allowing consumers to know how much trans fat is in the foods they choose to eat. Read the Nutrition Facts panel in order to choose foods with no trans fat most often in order to keep consumption of it low.
The energy obtained from fat plays an important role for both high intensity and endurance sports. Fat serves as the primary fuel for low intensity and long duration activities such as marathons, triathlons, and cross country skiing. In high intensity activity, where carbohydrate is the primary fuel, fat is necessary to fully release the available energy in carbohydrate.
Fat can either be bound (like stored fat in adipose tissue) or free (circulating in the blood). Fat in the free form can be used directly as an energy source by most tissues (except the brain) including exercising muscles.
Although fat is an available energy source, the use of it as an energy source is limited due to the following factors
- Fat is slowly digested in the stomach, which extends the amount of time until the energy can be utilized.
- Fat can contribute to gastrointestinal discomfort and indigestion during exercise.
- Stored fat in adipose tissue must be broken down and transported to the exercising muscle before the energy is readily available to the exercising muscle.
- Finally, to fully release the energy available in fat requires a greater amount of oxygen, which can be a limiting factor and slows energy availability.
Due to these factors, the timing and amount of fat consumption is very important. As a rule of thumb, fat consumption should be kept to a minimum in the meal before exercise and for a snack during exercise. A small amount of fat will contribute to satiety, but not energy for the exercise. The best time to incorporate healthy fats into the diet is when a bout of exercise is not scheduled within the next 6 hours or so.
How to incorporate healthy fats into the diet
There are many ways to incorporate the healthy unsaturated fats into your diet. If you like to bake, some recipes such as low fat muffins, bars and cakes work well when substituting oil for shortening or margarine. Choosing vinaigrette based (with healthy oils) salad dressings rather than regular salad dressing is another good choice. Adding some nuts into a casserole or salad for crunch, and olives or avocado on your sandwich are examples of good additions of healthy fat. Although avocados are high in fat and calories, they are rich in healthy fat and when used in moderation add nutritional value to your diet.
Here are some more ideas on how to add healthy fats to your meals/snacks:
- add almonds to oatmeal
- peanut butter sandwich
- flaxseed on cereal
- flaxseed in yogurt or muffin
- oil and vinegar on salad
- nuts in a salad
- fish (not deep fat fried)
- avocado in a salad or by itself
- add olives
- cook with olive oil include
- soybeans as a side dish
- tuna sandwich (little or no mayo)
- granola bar with nuts
- peanut butter on crackers
How to lose excess body fat
If you are overweight and would like to lose excess body fat, the major issue to consider is calories. Even if everything you eat is fat free or low fat, you will not lose weight if you consume more calories than you burn. Remember that carbohydrates and proteins can be converted into fat if they are not needed for energy or protein production.
Low and fat free products can be used as part of a calorie restricted diet to decrease the total caloric consumption and induce weight loss. Fat contains more than twice the amount of calories per gram than carbohydrates and protein, thus cutting out excess fat will cut calories from the diet twice as fast. In addition, fat is more readily stored as fat because does not have to be converted, like carbohydrates and protein.
To lose excess body fat, increase physical activity and/or decrease calorie consumption. Try to identify those items that you consume that contain high amounts of calories, and either find lower calorie options or use smaller serving sizes. The bottom line is, you have to burn more than you consume. If you are gaining weight you need to reduce caloric intake or increase physical activity or both.
Fat and cholesterol of common foods
|Item||Amount||Fat (g)||Cholesterol (mg)|
|2% low-fat||1 cup||5||20|
|Mozzarella, part skim||1 oz||5||15|
|Cottage Cheese, 1% fat||1/2 cup||1||5|
|Exclusive Brands with 16% fat (Ben & Jerry®, Haagen-Dazs® etc.)||1/2 cup||12-18||40-50|
|Common Brands with 10% fat||1/2 cup||5-10||30-35|
|Meats and fish (cooked)|
|Pork, roast loin||4 oz||8||85|
|Beef, 90% lean hamburger||4 oz||18||95|
|Ham, canned lean||4 oz||6||50|
|Chicken, roast breast||4 oz||2||95|
|Tuna, canned white||4 oz||3||45|
|McDonald's Big Mac™||4 oz||34||85|
|McDonald's® chicken nuggets||6 pieces||15||35|
|McDonald's® chicken select premium breast strips||5 pieces||33||90|
|McDonald's® Bacon Ranch Salad w/grilled chicken||10.2 oz||9||85|
|Subway®, Oven Roasted Chicken Breast 6"||236 g||5||4|
|Subway®, Turkey Breast 6"||22 g||4.5||20|