Flavors for the taster, buffers for the hungry
One of my friends once said at a dinner that eating foods devoid of fat could be compared to eating cardboard. That’s perhaps the reason for cuisines that favor taste like those from the Mediterranean countries to make generous use of oils and butter. Butter enhances many flavors as it creates a temporary coat inside the mouth and helps taste buds feel more of the food that it comes with. If we are to think about a world with fewer animal products and more plant-based ingredients, I find it hard to believe that a salad without oil can taste very good. I find it even harder to believe that the person who eats it will finish the salad with any sense of satiety in the absence of a copious amount of oil. Since we can only sustain lifestyles that give us pleasure and make us feel full after a meal so we do not want to snack shortly after, the role of fats appears to be central toward this goal.
Types of fat
We are looking to better understand nutrients, which requires to go beyond reductionism and over simplification. Just like there is not just one type of protein, one type of carbohydrate, there are multiple types of fats. So, when we use this term we have to ask ourselves, which kind?
- Saturated fats, which are mostly found in animal products.
- Mono-unsaturated fats.
- Poly-unsaturated fats, including the omega-3 and omega-6 fatty acids.
According to the National Academy of Science, saturated fats and mono-unsaturated fats are not indispensable in the diet, due to the premise that the body can synthetize them. But they are essential to the proper functioning of cell membranes and other functions. Therefore, we need to acquire them by our body making them, or optionally through diet. Poly-unsaturated fats are also essential, and it is harder for the body to synthesize omega-3 and omega-6, which means we have to avoid deficiency from these primarily through diet. Trans-fats have had some bad press in the past few decades as not being beneficial for anything, so they are listed as not essential.
Risks for cardio-vascular disease increase with the total count of cholesterol. Cholesterol in the blood is made of high-density lipoprotein (HDL), sometimes referred to as good cholesterol meaning higher levels may not be harmful or raise the risk factor for cardio-vascular disease, low-density lipoprotein (LDL), known as the bad cholesterol, so today, science tends to look at the total number and LDL, both of which should be on the lower side. So what is the role of fats in all this? Unsaturated fats appear to be neutral, but saturated fats and trans-fats are linked with increased LDL concentration. When LDL levels go up too much, the incidence of heart disease goes up as well.
Fat consumption is often invoked in the risk factors for heart disease, and one of the primary risk factor for cardio-vascular disease is cholesterol.
Much of the saturated fats come from animal sources. The vegan argument is that by avoiding animal products, you are essentially working to lower your LDL and total cholesterol levels, thereby lowering the risk factor for heart disease. Conversely, consuming animal products in excess directly impacts LDL level and heightens the risk. We discussed Dr. Ellsworth Wareham’s point of view in Robustness, and it is important enough to repeat some of the points here. Wareham was a cardio-thoracic surgeon his entire life and performed heart surgeries until the age of 95. He is now over 103, and in one of the rare interviews he gave, he pointed to saturated fats and cholesterol as the primary drivers of heart disease. According to him, if you keep your total cholesterol under 140, you considerably lower your risk of developing the disease. So out of the fats available to us, keeping the saturated ones in low amounts and avoiding trans fats completely, sums up the research to this day to reduce common risk factors.
Fat as fuel: our own body fat as a nutrient
The human body is like a hybrid car engine, able to use two fuel sources at the same time. The primary source of fuel comes from carbohydrates. We consume them and these carbs get stored in our bloodstream, in organs, and especially inside our muscles in the form of glycogen. Carbs provide an efficient source of energy that can be quickly used. However, we can only store so much of it, and the rest gets stored as fat. When the body runs low in carbohydrate energy supply it does two things. The first is that it slows down. Athletes who train for several hours often experience the feeling of hitting the wall, that is, running out of energy and having to dramatically reduce their pace. For a marathon runner, hitting the wall often means going from running at a good pace to a hard transition to walking and feeling faint for the rest of the distance. During this time, the body still functions, but it operates a challenging transition to the secondary fuel: fat, stored in our adipose tissue. We have much higher reserves of fat than carbs, but it is metabolically less efficient to tap into these reserves. Because the body uses carbs first, our cells are used to have fat as a backup resource, and they don’t know how to turn on the fat burning switch as a primary energy source, unless you train them to. This is how we arrive at the ketogenic diet.
Most organs in the body are able to use fat or carbs as energy source, except for one: the brain. Since at some point during our lifetime we are going to be in a situation of starvation in which our body has run out of carbs, this situation would be life threatening if we could not refeed immediately. Most likely, some generations of human beings died in this very situation, until our genes adapted to an interim solution: the body’s ability to synthetize ketones. Ketones are sugar-equivalent molecules that our body produces when we run out of carbohydrate energy supply, and these ketones are used primarily to feed the brain during this time. From the word ketone, the ketogenic diet became a concept. If we can train our metabolism to favor fat as an energy source, we can then tap into reserves not available otherwise. Some of the ways of doing this include intermittent fasting, during which the body goes into protection mode and utilizes fat as a source. It also burns weak and deficient cells, cleaning us from within: this is the process of autophagy. But as we discuss in the section on fasting, these exercises require precision and speaking to your physician to make sure you do not have any condition that could be further aggravated. The ketogenic diet also emphasizes a pyramid of nutrition where we consume more healthy fats. There are many applications to becoming able to use fat as fuel. Athletes can be in better shape to run a long-distance race without hitting the wall and transitioning to fat burning while keeping a strong pace until the finish line. Those looking to lose weight will have an easier time doing so, compared to the previous state where their metabolism could only store energy into body fat, but not retrieve it, converting body fat into energy. From going one way, now you can go two ways.
 Page 441, Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids, National Academy of Science, ISBN 978-0-309-08537-3 | DOI 10.17226/10490, https://www.nap.edu/catalog/10490/dietary-reference-intakes-for-energy-carbohydrate-fiber-fat-fatty-acids-cholesterol-protein-and-amino-acids
 “As with saturated fatty acids, there is a positive linear trend between trans fatty acid intake and LDL cholesterol concentration, and therefore increased risk of CHD.” Page 423, Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids, National Academy of Science, ISBN 978-0-309-08537-3 | DOI 10.17226/10490, https://www.nap.edu/catalog/10490/dietary-reference-intakes-for-energy-carbohydrate-fiber-fat-fatty-acids-cholesterol-protein-and-amino-acids