Fat - Why, what and where?
Fat has many faces and goes from enemy to superhero faster than you can shout "keto". One day we should eat more, then one day we should cut back. No wonder people get confused, even more so than they get about good carbs and bad carbs, or about how much protein is too much or too little. Let's start with the basics, what it is, what it does, where it is and why some of it is great and some of it isn't.
The basic functions of fat
Fat is one of three macronutrients, and is also known as lipids. There are many different types of lipids, just like the different types of carbohydrates or proteins. Fatty acids, saturated or trans fats are all different types of lipids, or fat, and will be reviewed in the next section. It plays multiple roles like providing us with energy, 9 calories per gram to be exact, when carbs aren't available. When in excess, fat can be stored in fat tissue and can release fatty acids when energy is required. Fat is also the main structural component of cellular membranes, which is made mainly of phospholipids, triglycerides and cholesterol. Yes, each and every cell of our body is composed of fat. Our brain is 60% fat, and made specifically of the fatty acid DHA (docosahexaenoic acid), which also plays a major structural role in our eye's retina.
Fat is required for intestinal transportation and absorption of vitamins A,D,E and K. This is specifically why doctor's suggest taking your vitamin D supplements or vitamin D-rich meals with the fattest meal of the day, increasing the vitamin D's absorption.
Certain fatty acids, like LA and ALA (discussed in the next section), are essential, meaning they must be obtained through our diet since the body can't produce them on its own. Fatty acids are then converted into compounds essential for many biological functions, like blood clotting, wound healing and inflammation. Leukotrienes and prostaglandins are just some of the compounds that stem from fatty acids we eat, and these play integral parts of the inflammatory and anti-inflammatory response.
Fat is also stored preferentially in certain fat tissues around the body. Some of them surround and protect vital organs like the heart or bowels, and excessive fat tissue accumulation will hinder others from functioning properly, like the liver, the pancreas or the lungs.
So fat exists in many forms, and when the right types of fats are consumed in the right quantity, they contribute to optimal health. In the modern world, where shelf-life, convenience, mass-production and price have become more important than nutrition and health, natural healthy fats present in whole foods that grow in the ground have been replaced by processed and disease promoting fats.
How much is too much?
Daily calories from dietary fat should typically fall into the 20-40% range. Experts recommend 30%, since many biochemical processes, including hormone synthesis and vitamin absorption, depend on fat intake.
If your calorie goal is 2000 per day, then by multiplying this amount by 30%, you'd get 600 calories from fat in a typical day. Since there are 9 calories in a gram of fat, 600 divided by 9 would be equal to 67g, representing the amount of grams of fat allowable per day. The goal isn't necessarily to limit fat intake, but to choose healthier fats, or foods that contain proper nutrition while delivering good quantity and types of lipids. Excessive fat intake will lead quickly to weight gain through fat storage in fat tissue. If you remember, fat has more than double the calories per gram than carbs or protein have, so overeating grams of fat will rapidly lead to excessive calories. Experts agree that we should be changing the types of fats we're eating, and limiting the excessive amounts we see in today's modern diets, in particular saturated and trans fats, associated with animal products and processed foods. But too low of fat intakes will also have negative health impacts, since fats are associated with many vital functions. The recommended daily intakes for the subtypes of specific fats will be reviewed in the next section.
Body fat percentage
BF percentage represents the weight of fat tissue carried in proportion to total body weight. It represents the essential fat that supports many vital functions and storage fat. BF can be measured by multiple methods, including calipers, bio-impedance and DEXA scanning, and many others. The catch still is the fact that BF percentage is not a direct measure of health, but rather a small piece, which is total caloric intake. Although excessive fat intake will usually lead to excessive calorie intake, it's excessive calories from any macronutrient that will cause increased fat storage and increased BF percentage. Remember that BF percentage is simply one of the many markers of health and that some people will have normal BF percentages but can still be unhealthy. The American Council on Exercise has illustrated BF percentages and how they differ from the specified groups. You might notice that women seem to have higher BF percentages. These can be attributed to the role that fat storage plays in reproduction and fertility.
Description Women Men
Essential fat 10–13% 2–5%
Athletes 14–20% 6–13%
Fitness 21–24% 14–17%
Average 25–31% 18–24%
Obese 32%+ 25%+
Fat as an organ
Fat, or body fat, is also known as adipose tissue, which is composed mainly of specialized loose connective tissue containing adipocytes. Adipocytes are the cells that contain the lipids that store energy. They also insulate the body and provide protection for vital organs. Although we always thought of adipose tissue as an inert substance, research has confirmed that adipose tissue is a major endocrine organ, meaning that adipocytes produce and secrete a multitude of hormones.
Adipocytes produce important hormones like leptin, immunomodulating cytokines and estrogen. Leptin is a hormone involved in hunger control. Adipocytes produce leptin in response to excess fat intake and storage. It is thought that people chronically ingesting excess calories from fat, like those eating the SAD (standard american diet), have decreased response to leptin. Cytokines are inflammatory chemicals produced by fat cells. Overweight and obese patients have chronically elevated levels of cytokines, which puts them in a chronic inflammatory state. This leads to increases in the risk of heart disease, diabetes, cancer, arthritis and multiple other health conditions. Adipocytes also produce estrogen, and excess body fat is directly linked to an increased risk of hormone dependent cancers, like breast and endometrial cancer.
Fat is far from being inert. In addition to having mechanical implications on joint overuse, back pain, sleep apnea, all related to excess weight being carried, there are also previously unrecognized hormonal implications of having excess body fat, or adipose tissue.
The different types of body fat
There are two different types of adipose tissue, white adipose tissue (WAT), and brown adipose tissue (BAT). WAT is mostly responsible for energy storage and hormone production, while BAT is mostly responsible for generating body heat.
WAT responds to insulin release by triggering a phosphorylation cascade that leads to the release of fatty acids from adipocytes which then enter muscle and cardiac tissue and serves as an energy source. WAT is mostly located underneath the skin (subcutaneous adipose tissue), or surrounding abdominal organs, called intra-abdominal or visceral body fat.
BAT is present in all mammals, and its main function is thermoregulation, which means body temperature control. It's most abundant in newborns and in hibernating mammals. Although still present in active adults, its quantity decreases with age. BAT produces heat, like shivering muscles, but through a process called non-shivering thermogenesis. Its brown color is a result of more iron containing mitochondria and capillaries in comparison to WAT.
Although metabolically active, WAT will be the main focus when talking about excess body fat, since excessive calorie intake over the long term will mostly impact this type of adipose tissue.
Just like carbs and protein, fats aren't created equal. Some of them have proven health benefits, while others are known to harm. In this section, we will cover them and help guide you through plant foods that contain healthy fats.
The different types of dietary fats
Total daily fat intake should be close to 30%. Too much and you risk excessive calories intake with all its baggage, and too low, meaning less than 10-15% and fat's vital functions can be compromised. There also exists recommendations for intake of specific types of fat. Let's start by reviewing the different sub-types of fats and the next section will focus on their plant sources.
the 4 main types of fats, or fatty acids, are:
Their main differences are directly related to their chemical structures, but we'll spare you the organic chemistry course. In simpler terms, all fats are made with carbon, hydrogen and oxygen. Saturated fats are saturated with hydrogen molecules and contain only single bonds between carbon molecules. On the other hand, unsaturated fats have at least one double bond between carbon molecules.
This saturation of hydrogen molecules results in saturated fats being solid at room temperature, unlike unsaturated fats, such as olive oil, which tend to be liquid at room temperature. Keep in mind that there are different types of saturated fats depending on their carbon chain length, including short-, long-, medium-, and very-long-chain fatty acids — all of which have different effects on health.
Saturated fats are found in animal products like milk, cheese, and meat, as well as tropical oils, including coconut and palm oil.
Unsaturated fats contain the monounsaturated and the polyunsaturated fats. These are less dense and liquid at room temperature. Think of the liquid oils at the bottom of your jar of peanut butter. These are the good fats.
Monounsaturated fats contain the omega-9 essential fatty acids (EFA). These can be produced by our body, so we don't need much from our diet, although there are still benefits of including them in your diet. They have been proven to decrease inflammation, improve insulin sensitivity, increase HDL (the good cholesterol), decrease bad LDL cholesterol, and help decrease the risk of heart disease.
Polyunsaturated fats are made up of omega-3 and omega-6 fatty acids. Contrary to omega-9, the omega-3 and omega-6 are 100% essential, meaning that they must be obtained through our diet. Omega-6 are primarily used for energy and are also used in many other biological processes. Omega-3 is the real hero. It has many benefits including the role played in the structure of our cell membranes. They decrease the risk of cardiovascular disease, play important roles in mental health, mood regulation, weight management and brain development. They help fight inflammation, help in preventing dementia, asthma, osteoporosis and fatty liver.
Here's the issue...we eat too much omega-6 and not enough omega-3.
Anthropological and epidemiological studies and studies at the molecular level indicate that human beings evolved on a diet with a ratio of omega-6 to omega-3 essential fatty acids (EFA) of ~1 whereas in Western diets the ratio is 15/1 to 16.7/1. A high omega-6/omega-3 ratio, as is found in today's Western diets, promotes the pathogenesis of many diseases, including cardiovascular disease, cancer, osteoporosis, and inflammatory and autoimmune diseases, whereas increased levels of omega-3 polyunsaturated fatty acids (PUFA) (a lower omega-6/omega-3 ratio), exert suppressive effects. With today's modern dietary habits, a ratio of 3:1 is probably realistic and desirable. Since omega-6 is readily found in oils and processed foods, they're easily over consumed. Omega-3 on the other hand, are harder to come by and most eat omega-3 deficient diets.
Saturated fats are the bad guys. They are solid at room temperature, like butter, cheese and fats in red meat. They raise LDL, the bad cholesterol and increase the risk of heart disease. They also increase systemic inflammation. They should be consumed in small quantities, at less than 5% of total daily calories. That equates to less than 5 grams on a 2000 calorie diet. The biggest benefits are seen when saturated fats are replaced with polyunsaturated fats. Studies have also linked saturated fats with systemic inflammation and mental decline.
There's still lots of confusion regarding saturated fats, with conflicting studies finding contradicting results. Keep in mind that the source of saturated fat is also important. For example, we can assume that saturated fats from fast food are not the same as saturated fats from coconut, but for now, studies comparing both are lacking. My recommendation would be to eat a minimum of saturated fat, and when you do, eat whole plant foods where the saturated fat at least comes with beneficial nutrients.
Trans fats are the worst! They exist in two forms, some occur naturally in some animal foods and processed meats and dairy. The second type is processed. And artificial sources are pretty much the problem. The majority we consume are from these sources where we add hydrogen to liquid vegetable oils (which makes partially hydrogenated vegetable oil). This food processing creates a semi-solid oil that's used in baking and heavily processed foods, like cookies, pizza, chips, fried foods, shortening and margarine. They are linked to negative health outcomes across the board, and it's no surprise that my recommendation would be to avoid it at all costs. Lucky for you, if you're eating a plant-based diet, then you have nothing to worry about.
Fatty foods you should be eating
If you've read the previous sections, you now realize that fat is a much misunderstood macro. Although frequently villainized, not all fat is bad. When eating an appropriate amount (experts recommend 30% of daily calories) and eating the right ones, mostly those from plants, fats are not only good, they're absolutely needed for optimal health. So let's review the different types of dietary fats and their food sources, including those to eat and those to avoid.
Saturated fats are mainly from animal sources. Fat in beef, in dairy, in butter, in cheese, in bacon, processed meats, sausages, etc. You get the point, mostly animal products. But saturated fats also exist in plants, like coconuts, coconut oil, palm oil. Even these healthier sources of saturated fats should be minimized, unless eating the whole food where the unwanted fat at least comes packed with excellent nutrition. Negligible amounts can be found in nuts, seeds, avocados and olive oil and in these foods, the pros of their beneficial nutrients far outweigh their cons.
Monounsaturated fat - Omega-9
These omega-9 essential fatty acids can be found mostly in plant sources by eating nuts (cashews, almonds, walnuts), avocados, chia seeds, and coconut. Try always choosing the whole food version by minimizing oil versions of these foods. The nutrition in large part has been removed during the processing of these oils, and this has increased the food's calorie density (see the For Weight Loss page).
Polyunsaturated fat - Omega-3, Omega-6
This includes omega-3 and omega-6. Contrary to popular belief, you don't have to turn to fish from omega-3. Chia, hemp, and flaxseeds are excellent sources and can be mixed or sprinkled on any meal. Walnuts are excellent sources, and probably the most nutritious of all nuts. Edamame is an omega-3 and nutrient powerhouse, as are beans. Seaweed and algae are also great sources.
Omega-6 can be found in nuts and seeds, in soybeans, in corn, and in tofu. Processed oils contain lots of omega-6 but should be limited due to their lack of nutrition and high calorie density compared to whole food sources.
Trans fats are pretty much created through chemical food processing where liquid oils are turned into solid ones by hydrogenating them. They're pretty much non-existent in the whole food plant-based diet, so you have nothing to worry about.
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So if you decide to remember one thing, remember this: Good fats are good and you need them to support vital functions for optimal health. The issue isn't fat, it's saturated and trans fats in excess associated with the under-consumption of healthy unsaturated fats. The issue isn't fat, it's the excess calories that come with unhealthy and processed foods that have added bad fats to it, which dramatically increase calorie density, leaving you overweight, under-nourished and starved.
To avoid unhealthy saturated fats, minimize the amount of meat, dairy and cheese you eat. To avoid trans fats, minimize the amounts of baked and processed foods you eat.
To get more healthy unsaturated fats, eat nuts, seeds, legumes, avocados, tofu, and pretty much anything plant-based. Be careful with excess coconuts, coconut oil or palm oil, since these plant's fats are almost entirely saturated.
As for cholesterol, that's easy. Cholesterol doesn't exist in plants, only in animal foods. So if your diet is plant-based, or plant-centered, then you don't have much to worry about.