Fat Follies

There are several widespread misconceptions about fat that might be hilarious if they didn't lead to the poor health of millions of people:

Eating fat will make you fat.
Saturated fat is bad for health.
Polyunsaturated fat is good for health.
Low fat diets are good for health.

These misconceptions are partly responsible for the obesity epidemic and an important contributor to the the declining health of millions for people around the world. Here's the real truth about fat:

Eat more fat to lose weight.
Excess carbohydrates (sugar and starches) will make you fat.
Saturated and monounsaturated fat are good for health.
Polyunsaturated fat should be restricted to about 4% of total calories.
Artificial trans-fats should be avoided completely.

Eat Fat Lose Fat

Eating more fat to lose weight seems like an oxymoron. But ironically, because of the satiating effect of fat, most people eat fewer calories in the long run when they eat a higher percentage of calories as fat. And eating fewer calories will lead to weight loss if your activity levels remain the same.

Eat Carbs Get Fat

When you eat more carbohydrates than you burn, your body converts the carbs to saturated fat and stores it in fatty tissue. Eating large amounts of refined carbohydrates, like sugar and white flour, causes a rapid rise in blood sugar levels. In healthy people,the pancreas then releases insulin to reduce blood sugar by storing small amounts as glycogen while large excesses are stored away as fat. Diets that are high in refined carbs often lead to a roller coaster ride with a blood sugar high followed by a blood sugar crash. With the blood sugar high, you may briefly feel happy and energetic. But when your blood sugar crashes you will likely feel tired, irritable, and hungry. If you then eat more refined carbs, you keep the roller coaster ride going. Over time, it can lead to obesity and insulin resistance and then type II diabetes.

Saturated versus Polyunsaturated Fat

Saturated fats have falsely been blamed for increasing risk to heart disease largely because they tend to raise low-density lipoprotein (LDL) "cholesterol" levels. Likewise, polyunsaturated fats are supposedly heart healthy because they reduce LDL "cholesterol" levels. But LDL levels are not a strong indicator of heart disease, and in fact oxidized LDL is a much stronger indicator. How does LDL get oxidized? Polyunsaturated fats are more prone to oxidation in processing, storage, and cooking, and when ingested, they end up in LDL. It's the oxidized polyunsaturated fats that greatly increase heart disease risk.

Saturated fats are mainly from animal foods that have been predominant in healthy human diets for hundreds of thousands and perhaps millions of years. The change to more animal foods may be largely responsible for increasing human brain size and our evolution away from apes. So, it doesn't make much common sense that foods that nutured our ancestors for so long are now suddenly bad for us.

In contrast, polyunsaturated fats were low in our ancestral diets and have increased dramatically in consumption the last 100 years with the large-scale production of cheap vegetable oils like soybean oil, corn oil, safflower oil, and sunflower oil. Also, entirely new to the human diet within the last 100 years, are artificial trans-fats, mainly in the form of partially hydrogenated vegetable oils. Trans fats appear to be even worse than polyunsaturated fats in causing health problems.

Polyunsaturated fats suppress the immune system and are involved in immune dysfunction as well. This effect increases the risk of illness and of a variety of cancers, as well as autoimmune diseases and an increased risk of asthma. Polyunsaturated fats also inhibit enzymes and thyroid function that are vital for bodily processes. Furthermore, they cause age spots on the skin because they are easily oxidized by sunlight and the oxidized fats damage skin cells. Oxidized polyunsaturated fats also wreak havoc elsewhere in the body and are implicated in inflammation, atherosclerosis, heart disease, and cancer.

Traditional Diets

Traditional diets typically had about 4 to 10 percent of total calories from polyunsaturated fat, with a ratio of omega-6 to omega-3 polyunsaturated fat of 2 to 1. The low end of the traditional range appears to be an optimal amount for a healthy diet - around 4% of total calories. It's mainly the omega-6 polyunsaturated fats that have increased greatly in modern diets, primarily from vegetable oils that are used in processed foods and cooking.

Traditional diets were also low in sugar and keeping sugar to less than 10% of calories is probably ideal for optimal health as well. In the modern diet, most sugar comes in forms that are about half fructose, such as table sugar and high fructose corn syrup. Large dietary intake of fructose is implicated in a variety of metabolic syndrome problems, including insulin resistance, elevated triglycerides, abdominal obesity, elevated blood pressure, inflammation, oxidative stress, endothelial dysfunction, microvascular disease, hyperuricemia, glomerular hypertension and renal injury, and fatty liver.

PUFA in Meat and Dairy

The following tables show the percentage of calories analyzed as polyunsaturated fat calories in a variety of meat and dairy foods for reference. The data are from the USDA nutrient data base and are more likely to be representative of typical commercial meat and dairy products. Unfortunately, the USDA does not have data for pastured animal products, but game meat may be closer in this regard. Click on the tables to enlarge them.

Meat and Dairy

Game Meat