Fat is like high-waisted pants and shoulder pads, only yummier; it cycles in and out of fashion over the years. Fat is just emerging from half a century of villainy as the prime cause of heart disease, but is now accepted as a component of healthy eating by even the conservative, and positively deified by the low-carb community. Let’s figure out what functions fat serves in the body, and what happens if we eat too much or little of it. (This is the third post in the Macronutrient series: Intro and Protein.)
Fat has important structural roles in the body. It is completely essential for the health and function of every single cell in your body, which is surrounded by a membrane made of fats. While we already know that some hormones are composed of protein, the remainder are made of fats and cholesterol. While excess stored body fat is correlated with poor health, having some fat stores helps to protect our internal organs and provide shape and curves to the body.
Fat is also the preferred fuel for our mitochondria, the organelles responsible for generating most of the energy in our bodies. It can be burned using oxygen as a steady and long-lasting energy source. Fat is the ideal energy source for walking, chores around the house, playing with the kids, golfing, easy biking, and any other activity at low-to-medium intensity. The only cells in the body which cannot utilize fat for energy are red blood cells and nerve cells.
But isn’t having too much body fat bad for you? Doesn’t that mean that “eating fat makes you fat?” Yes, having a high body fat percentage is correlated with health concerns, but that does not make the fat itself the cause. Of course, if we eat more food than we can use for energy or building materials, the extra will be converted to fat for storage - but the fact that our bodies store excess energy (even energy that started as protein or carbs!) as fat should indicate that the fat itself is not dangerous to us. Our bodies know what to do with fat, it can be used by nearly every cell in the body, and it’s not toxic.
Let’s take a tiny little excursion into the land of “Calories In, Calories Out” (CICO) right now. It’s a huge topic, and you can anticipate another geek-out post in the future, but let’s devote thirty seconds of brain power to it right now. CICO is a true statement, in that “if you consume more calories than you expend, you will gain weight,” but it is not as simply manipulated as the “eat less, move more” brigade would have you believe. Yes, we have (supposedly) total control over the “calories in” side of the equation. We can weigh, and measure, and track, and avoid happy hour. But it’s impossible to have the same level of control over the “calories out.” Of course, you can meticulously count your steps, or rack up an hour on the treadmill, or run five miles. But you have no control over how your body will respond to having inadequate fuel for the demands you make on it. Our bodies are the pinnacle of billions of years of evolution - we derive from eons of ancestors who managed to not starve to death before they could reproduce. They are not easily tricked. Our metabolic response to apparent starvation is to downregulate inessential functions, reduce body temperature, and get tired. How many of you have fallen asleep on the couch in the middle of the afternoon while cutting calories? This doesn’t mean we’re doomed to carry that extra padding forever, it’s just a plea that we respect our bodies for the amazing machines that they are, and find ways to work with them to upregulate metabolism instead of beating ourselves down (in so many ways). More on that in the future - I want to get the macros out of the way first, so we know how our food helps us build our most awesome selves. OK, I lied, that was more than thirty seconds, but I get a little fired up about this.
Back on track! So maybe you’ve heard about “good fats” such as omega three fats, and “bad fats” such as omega six? This is a generalization of our requirements for the Essential Fatty Acids (EFA). An essential nutrient is one our body can’t make for itself, so we have to get it from food, and both omega three and omega six fall in this category. Omega six fats are involved in the inflammatory processes, such as the redness and swelling you see at an injury site. This is important and healthy, and initiates the tissue repair process. It is balanced by the anti-inflammatory processes, which are mediated by omega three fats. So both fats have a role to play in the healthy functioning of our body, but they need to be balanced, ideally in roughly 1:2 omega 3:6. Unfortunately, the average American diet provides roughly 1:20 omega 3:6, and many people’s anti-inflammatory pathways just can’t keep up. So rather than labeling omega three as “good” and omega six as “bad,” we should seek to balance our intake. Omega three fats are generally found in foods with green plants and algae at the base of the chain, such as fish and grass fed animal foods. Omega six fats are generally found in foods derived mainly from seeds, such as conventionally farmed animal products and seed oils.
We’ve established that fat is structurally important, that it’s a valuable energy source, and that we want to balance our essential fat intake. So, how much fat should you eat? I’m going to give you another “that depends” answer; most people will find themselves in the 40-80g/day window. We can picture fat consumption as a continuum - the very lowest end is unhealthy fat avoidance. Consuming too little fat, and especially essential fat, will result in our hormones getting out of whack. Those of us who consume larger portions of carbohydrates will require proportionally less fat, and those who choose to limit carbs can get more of our fuel from fat. If we’re seeking to encourage our bodies to use some of our stored fat for energy, we may want to slightly reduce the amount of fat we consume, keeping other macros constant. (More on that another time, this is reaching Shakespearean proportions already!)
Stay tuned for all the drama of Carbohydrates, coming soon!