Your body has a relatively fixed number of fat cells. They don't come and go when you gain or lose weight (unless the person is morbidly obese, in which case the person has literally filled their fat cells to capacity and must create more to handle the load). Rather, they empty out or fill up, like water balloons. The biochemical processes that store excess sugar as fat in the body are a means of balancing your blood sugar levels, not taking fat molecules one-for-one and sticking them to our belly, butt, or thighs.
Eating fat does not make you fat. If you question that, then consider this: in the last forty years, American fat consumption has dropped dramatically with hundreds of low-fat alternatives to whole milk, butter, cheeses, and dressings, not to mention the shift in meat consumption toward much leaner varieties. Yet, as a nation, we get heavier and sicker.
Fats, an introduction
Fats come from animal and vegetable sources. The human body can produce most of the specific varieties of fats it needs from a healthy nutrition plan, except for two. These Essential Fatty Acids come in the form of a type of Omega 3 (ALA) and a type of Omega 6 (LA). Human beings must consume these fatty acids in their diet.
The human body needs fat to function effectively. Fats in the blood are required to absorb and utilize proteins and certain vitamins. Fats are an essential component of joint health. Fatty acids are required to promote and support synaptic activity in the brain. And fats are essential to cell health. We don't think about our cells much. But damaged cells are a problem. Beauty commercials talk about free radicals, but what are they? Free radicals are damaged cells on a mission. Our cells have a natural "self destruct" code that causes them to die off and then be replaced by new, healthy cells. Free radicals are cells that refuse to die. What's more, they seek out other cells and damage and mutate those as well. Cancer occurs when damaged cells multiply and spread. So, without putting too fine a biochemical point on it, free radicals are "baby cancer" which may or not grow up into something nasty. Suffice to say - we need fats in our diet.
Cholesterol is an incredibly complex subject and there is still a good deal of controversy in the medical and nutritional communities about risks, benefits, and management mechanisms. But sometimes a simplified version is what you need for a foundation to build on.
Cholesterol is the natural mechanism for all mammals to transport fats (lipoproteins) through the body to repair and support cells of all types. You can't get rid of it and you wouldn't want to. Unfortunately, in an effort to warn people about the risks of heart disease, the medical community and, along with it, many government agencies have managed to demonize an essential function without creating a lot of clarity. Clarity is good, don't you think?
Most people understand the difference between arteries and veins. Arteries circulate oxygen throughout the body while veins return the oxygen-depleted blood back to the lungs to get more. When we work hard, our muscles need more oxygen. Our heart beats faster, our lungs pump harder, and the rate of circulation increases. This is all to maintain a constant level of balance of oxygen at the cellular level.
Apply that thinking to cholesterol. In general terms, Low Density Lipoprotein (LDL) is associated with distributing essential fats to our cells. High Density Lipoprotein (HDL) is associated with clearing unneeded fats from the blood. Instead of the heart, this system is controlled by the liver. Just like oxygen, the body strives to maintain a certain balance of cholesterol in the blood. If there is plenty present, the liver decides not to produce more. And, just like oxygen, if you decided to take it upon yourself to breathe heavily and quickly for no particularly good reason, you'd overload yourself and get dizzy, with no benefit, because your cells didn't need the extra boost. With cholesterol, you can "breathe heavily" by over-ingesting fats and dietary cholesterol that spills directly into the bloodstream through the digestive process. The liver isn't making any, but you're still shoving it into your system. And, because you've overridden the body's natural regulation system, you're pumping a lot of LDL in without a corresponding increase in HDL.
I want to say it again: I'm oversimplifying an immensely complex process, but in principle it stands.
At this point, we have to come back to carbohydrates. As I said earlier, the organ that regulates cholesterol production ("good" and "bad") is the liver. Constant overconsumption of refined carbohydrates in the form of refined flour, rice, and sugars overloads the liver. This overload (it's not clear precisely how) inhibits the production of HDL - the "clearing out" cholesterol. As a result, you have more in than out. Anybody that's had a backed up sink can identify with this principle.
Restricting your refined carbohydrate intake will improve your liver function and reduce your insulin resistance, which will improve your ratio of HDL to LDL, which, in turn, is a major factor in reducing your risk of heart attack or stroke.
"Good" fats and "Bad" fats
The pop fitness world has sold us a dizzying array of "good" and "bad" fat messages over the years. As I said in Part 1, "good" and "bad" as universal labels aren't helpful. But, like gas station sushi (thank you esurance commercials), some choices are clearly better than others.
The first thing that makes classifying foods by their "good" or "bad" fat content is that most foods have a combination of fat types. For example, lard, about as "uncool" a fat selection by today's standards as you could find, is about equal parts saturated and monounsaturated fats, with 10 percent polyunsaturated as well. Nature, it seems, likes to keep some of her mystery. In the graphic below, examples are given based on the primary source of fat provided by the food.
|The Fat Pyramid. More from the bottom, less from the top.|
So, how many fat calories do I need?
Fats are more than twice as dense, calorically, as carbohydrates and protein (9 cal/gram as opposed to 4). Depending on your specific health conditions, activity level, and personal goals, you may choose a different threshold, but a good rule of thumb is to keep your fat intake somewhere around 30% of your total calories. As a simple guideline that would mean keeping your portions of fats to 1/2 the size of carb or protein, by weight, as a portion of your total intake.
If you are taking dietary supplements for essential Omega 3 (ALA) and Omega 6 (LA), and are looking for a way to reduce your total calorie intake somewhere, you could trade some fat grams for protein, taking it down to as low as 20% for a while, but for most, there's no need to do this as part of a long-term nutrition plan.
Since fats are most often a component of food that also includes protein, you aren't going to have to look very hard to find ways to supplement with additional fat sources. If you're eating whole meats, eggs, and dairy products, you're probably doing just fine for fat intake. And don't forget your cooking techniques. We use a couple tablespoons of extra virgin olive oil in virtually all of our stovetop cooking, some of which makes its way onto your plate.
A few words about fat myths and misconceptions
"Low-fat foods = healthy:" As a cooking component, fat provides taste and texture to food. It is also essential as an emulsifier, binding particles together in the cooking process. When you take fat out, you have to replace it with other components that will substitute for these functions. Enter sugar, gluten, and a host of other things that are difficult to pronounce. Low fat foods will likely have more total calories (and empty ones at that), be less satisfying in texture and bite, and may well aggravate the systems of those who are gluten sensitive. Have you ever looked at a 5lb bag of sugar boasting the label "Naturally Fat Free"? Not exactly a believable health claim.
"Eggs yolks are bad for you:" This particular tidbit arose out of the storm against cholesterol. Unfortunately, it was based on lowering total cholesterol, rather than maintaining a healthy ratio of HDL to LDL. As long as you are mindful of your total intake of fats and cholesterol within your 30% (or whatever you choose), eat eggs. They're delicious and a great source of protein.
"Frying food is bad for you:" So many people jump to blame the "grease" in pan or deep frying food, while completely ignoring the food that got fried. The majority of popular fried foods are either low grades of meat or high carb items like potatoes, breaded in white flour. Oil conducts heat very effectively to allow food to cook extremely quickly, resulting in a nice sear and more tenderness than methods which take longer. At sufficient heat levels, very little of the oil is absorbed into whole foods like vegetables or whole cuts of meat. Look to the quality of the dish as a whole. There are a lot worse things than "grease". Just select the right oil for the job from the pyramid above. Another great resource is a detailed review of oils on Mark's Daily Apple.
"Fat will make you fat:" I know I started out with this, but it's really worth repeating. You need fat. Stored body fat is principally composed of excess carbohydrates (sugar) in the diet.
So, to recap: fear not the fat! It is an essential part of your nutrition plan. And, when managed effectively, makes for tasty choices and increased variety in your menu. In our final installment of the series, we will cover the "mother of all macros" (my term of endearment), protein. Until then!