In Part 1 and 2 of this series on dietary fat, we discussed how dietary fat can either promote weight maintenance or promote overeating. In Part 3 of this three-part series, we’ll ask if the inclusion of fat in our diet is healthful or harmful.
SOME DIETARY FAT IS NECESSARY …
Dietary fat is necessary to support normal physiological functioning. Essential fatty acids are types of dietary fats our body uses for many purposes, like for example, maintaining the integrity of our cell membranes. While saturated fat is often considered a “bad” fat, dietary saturated fat may be essential for the healthy function of the: cardiovascular system, pulmonary system, hormonal system, liver, skin, bone, eyes, and even your brain.
SOME FATS ARE THOUGHT TO BE HEALTHFUL
Unsaturated fats (mono and polyunsaturated), in particular omega-3 fatty acids (a polyunsaturated fat), reduce inflammation and may help lower risk of chronic diseases (heart disease, cancer, arthritis, etc). Omega-3 fatty acids are highly concentrated in the brain and there is a large body of evidence that omega-3’s are vital for cognitive performance. Symptoms of omega-3 fatty acid deficiency include fatigue, poor memory, dry skin, heart problems, mood disturbances, developmental issues and poor circulation.
SOME FATS ARE THOUGHT TO BE HARMFUL
On the other hand, saturated and trans fats have been shown to promote inflammation, disease risk and increases cholesterol. Even one high-fat meal can show measurable increases in blood pressure, heart rate and resistance in blood vessels. Additionally, the inflammatory processes promoted by certain fats can worsen asthma for hours after a meal.
The U.S. Department of Agriculture (USDA), the Department of Health and Human Services (HHS), and the American Heart Association recommend your daily diet be made up of less than 35% total fat, 10% saturated fat, 1% trans fat. For a 2000 calories / day diet, this would be no more than ~80g total fat, 20g saturated fat, and 2g trans fats.
Sure, this question is affected by the total quantity and types of fats consumed, but it is also influenced by the total amount of energy consumed (e.g., chronic overeating), what else a person eats (e.g., a high vegetable diet) how much a person moves, how they sleep, chronic stress levels, etc. Over a lifetime, these diverse influences impact the nature of our metabolism and how our bodies handle the nutrition we provide and it is conceivable that a type of fat (e.g., saturated fat) may be healthful in one context and harmful in another.
If you have a specific disease, disorder or condition, and your doctor (or health care provider) has made a recommendation about your diet, listen to her. If you’re looking for a healthy strategy for dietary fat, focus more on eating balanced meals from a diverse menu of food types, including variety in dietary fats, and don’t overeat at any meal (your body won’t handle 50 grams of dietary fat in one meal the same way it handles 5g).
FOOD SOURCES OF DIETARY FAT TYPES
Monounsaturated fat – Olive oil, peanut oil, canola oil, avocados, nuts and seeds
Polyunsaturated fat – Vegetable oils (such as safflower, corn, sunflower, soy and cottonseed oils), nuts and seeds
Omega-3 fatty acids – Fatty, cold-water fish (such as salmon, mackerel and herring), flaxseeds, flax oil and walnuts
Saturated fat – Animal products (meat, poultry, seafood, eggs, dairy products, and butter), and coconut, palm and other tropical oils