Dietary fat

A piece of salmon on a refreshing salad with a lemon wedge. Fork on stand by.

What is dietary fat?

"Dietary fat" refers to all of the fats and oils found in foods that come from animals and plants. Fats and oils contain fatty acids, of which there are two types-saturated and unsaturated.

Sources of dietary fat

Foods that provide dietary fat contain mixtures of saturated and unsaturated fats. If a food contains more unsaturated than saturated fat, that food is often called a "good source" of unsaturated fat. For example, vegetable oil is a good source of unsaturated fat since it contains mostly unsaturated fats.

Saturated fats come mainly from animal foods, such as meat, fish, poultry, eggs, and dairy products. They are also found in coconut, palm, and palm kernel oils, which are sometimes called tropical oils.

Unsaturated fats are found in higher amounts in plant foods, such as canola (a type of grain), corn, olives, and sunflower seeds. These foods, and the oils made from them, are good sources of unsaturated fat.

Dietary fat and your body

Your body needs both saturated and unsaturated fats for good health. Your body uses fat:

  • As a source of energy (1 gram of fat provides 9 kilocalories of energy)
  • As a source of essential omega-3 and omega- 6 fats needed for heart and reproductive health
  • To help form body cells
  • To help absorb vitamins A, D, E and K (the fat-soluble vitamins)

Health benefits of unsaturated fats

Choose unsaturated fats such as olive, canola, and sunflower oils when baking, cooking, and preparing foods. These fats provide essential nutrients, help prevent heart disease, support growth and reproductive health.

How much fat does your body need?

Dietary fat should make up 20-35% of the kilocalories that an adult eats in a day. For a woman, this is about 45-75 grams of fat per day, based on a total daily intake of 2000 kilocalories. Foods that are high in saturated or trans fat should make up no more than 10% of the kilocalories you eat in a day.

Can your fat intake be too low?

Most of us would not be harmed if we greatly reduced the amount of fat we eat. If you ate less fat than your body needed for a long period of time, you might develop an essential fatty acid or fat soluble vitamin deficiency.

Health risks of eating too much fat

Heart health

Eating too much fat, especially saturated and trans fat, can raise your risk of heart disease. The more saturated and trans fat you eat, the higher the levels of cholesterol and low- density lipoprotein (LDL) in your blood. Higher cholesterol and LDL levels are linked to higher heart disease risk.


While there are many causes of obesity, regularly eating more kilocalories than your body needs may lead to excess weight gain and obesity. Dietary fat contains more kilocalories per gram than carbohydrates, protein, or alcohol. Eating too much dietary fat can promote weight gain.

Breast cancer risk

In 2007, experts at the World Cancer Research Fund and American Institute for Cancer Research reviewed the research on food, nutrition, physical activity, and cancer risk. You can read their detailed report online at here. Here is a summary of their findings for breast cancer:

There is little evidence linking food and nutrition to breast cancer risk. This includes studies that looked for a link between dietary fat and breast cancer risk.

Some research has reported a link between eating foods rich in omega-3 fats and lower breast cancer risk. In the laboratory, scientists have shown that omega-3 fats may boost the immune system and weaken cancer cells. Researchers are trying to find out if these laboratory findings are also true in humans.

Since breast cancer risk is hormone related, the factors that affect it differ among pre-menopausal and post-menopausal women. Currently there is no evidence of a link between breast cancer risk and total fat intake among pre-menopausal women. There is a small amount of evidence suggesting that eating higher amounts of dietary fat may raise breast cancer risk after menopause. Until more research is done, we cannot say for sure whether or not there is a link between dietary fat and breast cancer risk.

What does this mean for you?

While the evidence about dietary fat intake and breast cancer risk is not clear, there is convincing proof of a link between having more body fat and higher breast cancer risk among post-menopausal women. This means that achieving and maintaining a healthy body weight may lower breast cancer risk among post-menopausal women. Along with regular physical activity and eating lots of vegetables, fruits, legumes, and whole grains, eating less dietary fat can help you achieve your healthy body weight.

Eating foods rich in omega-3 fats may benefit your health. Add a spoonful of fresh, ground flax seed to your breakfast cereal and eat fatty fish (herring, mackerel, salmon) 2 or 3 times a week to boost your omega-3 fat intake.