Fat is one of the three macronutrients of the human diet. Dietary fat is important for our survival and has many important functions in our bodies, such as being a major source of energy, metabolizing fat-soluble vitamins (A, D, E, and K), and obtaining essential fatty acids. Unlike protein and carbohydrates, fat is hydrophobic and is not soluble in water. In other words, water and oil do not mix, no matter how much you shake or stir these two substances.

The fact that fat has over twice as many calories per gram as protein and carbohydrates have made it the targeted nutrient for weight loss and reducing cardiovascular disease (CVD).  While overconsumption of the high-energy-density of fat can lead to weight problems and cardiovascular disease, consuming the recommended amount of dietary fat, as well as eating heart-healthy fats and oils, is important for promoting overall health and well-being.

Dietary fat is the most concentrated source of energy at 9 kcals/gram, which is more than two times the number of calories in carbohydrates and protein at 4 kcals/gm. The majority of excess fat intake is stored as triglycerides. While carbohydrates are the body’s preferred fuel source during physical activity, the body’s system turns to fat stored in the adipose tissue when carbohydrates are not available. 

 

There are two types of “good” unsaturated fats: Monounsaturated fats and

Polyunsaturated fats. The two major classes of polyunsaturated fatty acids (PUFAs) are the omega-3 and omega-6 fatty acids.Omega-3 fats are an important type of polyunsaturated fat. The body can’t make these, so they must come from food. Saturated fats are the type that raises blood cholesterol.

The American Heart Association recommends aiming for a dietary pattern that achieves 5% to 6% of calories from saturated fat.

 if you need about 2,000 calories a day, no more than 120 of them should come from saturated fat.

That’s about 13 grams of saturated fat per day.

Polyunsaturated fats are found in high concentrations in

  • Sunflower, corn, soybean, and flaxseed oils

  • Walnuts

  • Flax seeds

  • Fish

  • Canola oil – though higher in monounsaturated fat, it’s also a good source of polyunsaturated fat.

Monounsaturated fats are found in high concentrations in:

  • Olive, peanut, and canola oils

  • Avocados

  • Nuts such as almonds, hazelnuts, and pecans

  • Seeds such as pumpkin and sesame seeds

Biggest sources of saturated fat in the diet are

  • Pizza and cheese

  • Whole and reduced-fat milk, butter, and dairy desserts

  • Meat products (sausage, bacon, beef, hamburgers)

  • Cookies and other grain-based desserts

  • A variety of mixed fast food dishes

Omega-3 fats 

Omega-3 fatty acids (omega-3s)sometimes referred to as “n-3s,” are present in certain foods such as flaxseed and fish, as well as dietary supplements such as fish oil. Several different omega-3s exist, but the majority of scientific research focuses on three: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA).

  • The best way to get omega-3 fats is by eating fish 2-3 times a week.

  • Plant sources of omega-3 fats include flax seeds, walnuts, and canola or soybean oil.

  • Higher blood omega-3 fats are associated with a lower risk of premature death among older adults.

Trans Fats

Made by heating liquid vegetable oils in the presence of hydrogen gas and a catalyst, a process called hydrogenation. These fats are the worst type of fat for the heart, blood vessels, and rest of the body because they:

  • Raise bad LDL and lower good HDL

  • Create inflammation,  – a reaction related to immunity – which has been implicated in heart disease, stroke, diabetes, and other chronic conditions

  • Contribute to insulin resistance 

  • Can have harmful health effects even in small amounts – for each additional 2 percent of calories from trans fat consumed daily, the risk of coronary heart disease increases by 23 percent.