Continued from Part 1, in this post I will give a brief rundown of the physiological nature of fats to illuminate the reasons dietary fats do not actually cause body fat.
The complex substances grouped together as fats are essential for basic health. They energize, build, and fortify various tissues, and certain fats can even help lower your serum cholesterol. Besides the calories they provide for energy, fats are used to manufacture hormones and neurotransmitters. They also aid in the absorption of the fat-soluble vitamins A, D, E, and K and play key roles in regulating inflammation, chemical signaling, and the metabolism of other nutrients.
Not All Fats Are Equal
From bananas to bacon, there is fat in virtually every food, differing in amount and type. And whether we eat a burger, a sardine, or an avocado, we are eating a mixture of fats, both “good” and “bad.” According to the USDA, a stick of butter, for example, contains 51% saturated fat, 21% monounsaturated fat, 3% polyunsaturated fat. Olive oil has 14% saturated fat, 73% monounsaturated fat, and 11% polyunsaturated fat.
How much fat should you eat? The Institute of Medicine says fats should be 30-40% of total daily calories for children ages 1-3, and 20-35% of total daily calories for older kids and adults.
Dietary fats can be classified into two categories: unsaturated (the “good” fats) and saturated (the “bad” fats). Unsaturated fats come in two types: monounsaturated and polyunsaturated. Replacing saturated fats in the diet with unsaturated fats lowers blood cholesterol and the risk of cardiovascular disease. Desirable sources of these fats are healthy oils, nuts, seeds, fish and avocados.
Saturated fats are risky because they raise LDL (“bad” cholesterol) levels. As we touched upon, elevated LDL levels contribute to arterial plaque and increase the risk of diabetes, heart attacks, and stroke. Among the most common dietary sources of saturated fats are fatty meats and dairy products. The US population currently gets 11-12% of its energy from saturated fats and that hasn’t changed much over 15 years. It is generally recommended that saturated fat not exceed 10% of the daily fat intake, but some experts suggest getting it down to 5% would be healthier target.
The roles and benefits of omega-3 and omega-6 fatty acids are controversial and confusing. Both are essential fatty acids, which must come from our diet because our bodies cannot make them. They play key roles in every system in the body and are important in the regulation of many physiological processes and are crucial for the health of cell membranes and the neurological development.
There is growing evidence that most Western diets have too little omega-3 and this may affect immune system function and cause inflammation. Some scientists believe that the natural ratio of omega-3 to omega-6 fatty acids in the human diet is 1:1. In the typical modern Western diet, however, the ratio is about 1:16. That’s a big difference. Good sources of omega-3s include fatty fish, flaxseed oil, walnuts, and walnut oil.
Trans fats, artificially modified vegetable oils widely used in fried and processed foods, are undeniably bad guys. Trans fats are considered more harmful to your health—and especially your heart—than saturated fats. They have been shown to raise LDL-cholesterol, lower HDL-cholesterol (the “good” cholesterol), increase triglycerides, and contribute to inflammation, heart disease, stroke, and diabetes. Even a small amount—say 5 g, about the amount found in a serving of fast-food French fries—is enough to increase inflammation.
Body fat is complex
Body fat is getting more complicated. It was once thought of as basically inert; fat cells were like microscopic oil tankers that took on a small or expanding load of fat. Now we realize that fat is a very sophisticated and complex tissue. Fat in fact functions as an organ. Rather than just a passive or inert storage depot, fat is metabolically active and constantly communicating with other organs, including the brain, through a variety of hormones and chemical messengers.
The brain is the fattiest organ in the body. More than 50% of the dry weight of the human brain is fat. It is structural fat contained in the membranes of neural cells and a key component of the synapses, or connections, between neural cells.
Reading Your Fats Is Not So Tough
According to the American Heart Association, everyone over 20 years of age, regardless of their previous high cholesterol history, should have a blood cholesterol test at least every 5 years. If you’ve been diagnosed with high cholesterol, and are controlling it with diet, you should be tested every year. People who take prescription medications to control cholesterol levels, like statin drugs, may need to get their cholesterol tested at least twice a year to not only check cholesterol levels, but to also check liver function.
Today, many people know their cholesterol and triglyceride levels, just as they know their blood pressure. The theory is that the more thoroughly you understand these numbers and are able to put them to use, the more you’ll be able to maintain cardiovascular health. Frankly, ruling your life by the numbers makes for a miserable existence. Keeping vigilance over yourself tends to be a combination of prison guard and prisoner at the same time. No one reaches wellness by being statistically perfect. True wellness is beyond statistics, and even if medical markers are helpful, as of course they can be, the core of wellness lies elsewhere.