THE THING ABOUT FAT…
If you were born in the late 70’s or in the 80’s, you lived through the fat-free craze that permeated the health and nutrition space at the time. The low fat, high-carbohydrate diet has now been disproven and shown no benefit for weight- loss or disease prevention and management. In fact, in many cases it did more harm than good and led to a rise in metabolic syndrome and obesity.
And yet, I still meet people that seem to be in two camps: one ingrained in outdated thinking around fat, afraid that it will make them gain weight; the other that is not afraid of fat necessarily, but confused about what sources of fat are healthier, and how much of it to consume daily. This led me to want to set the fat-record straight on what the current research shows.
In this space I try to offer pieces of information around basic nutrition that are a little bit more nuanced than what you would find if you just googled, say, “is fat good for you.” If you do that, you’ll find that the topic is extensive, and that fat is essential for:
Gut health
Metabolic health and blood sugar balance
Nutrient absorption (fat-soluble vitamins)
Hormone production and balance
Healthy skin
Nervous system health
Mental, adrenal, and mood/emotional health
So if fat is important and necessary for many different functions, why was it demonized to begin with?
The most simplistic fact behind why fat was thought to cause weight gain, and the problems and diseases that come with being overweight, is that it has the highest calories per gram, 9, compared to carbohydrates and proteins, both 4 per gram.
What wasn’t taken into account is that consuming fat does not necessarily lead to fat accumulation on its own (in other words, a calorie is not just a calorie). What I’d like to focus on here are the mechanisms behind fat storage and fat utilization, and why dietary fat was erroneously vilified in the first place.
In order to understand this, let’s look at how energy from food is produced in the body.
How we transform the food we eat into energy
The food we consume is broken down into one of two forms of energy: immediate or stored for future use.
When broken down into immediate energy by the mitochondria in our cells, it’s called adenosine triphosphate or ATP. When stored, some of it will go to our muscles and liver in the form of glycogen–a form of stored energy that can be converted into glucose when needed–and the rest is turned into fat that’s stored in adipose/fat cells as triglycerides.
Note that this is true for any category of food, whether it’s fat, carbohydrate or protein. After immediate needs have been met, excess will be stored.
The survival switch
Our bodies evolved to store excess calories through different physiological mechanisms to help humans survive during periods of food and water scarcity. Being in fat storage mode is a survival switch that can be signaled under specific circumstances. Certain things can activate the signaling, for example, the presence of large amounts of fructose. Concentrated sodium in our blood is another one, which I explained in my previous post on salt.
Let’s take a look at fructose. Fructose is a carbohydrate chemically similar to glucose, and they’re both simple sugars. Glucose is what’s commonly referred to as blood sugar, and it’s our main source of fuel. It’s found in carbohydrates like grains, beans, and vegetables, but also in table sugar and fruit. Fructose is involved in energy storage rather than energy production and glucose is the sugar for energy production. Fructose is more concentrated in:
Fruit
High fructose corn syrup
Table sugar (composed of half glucose and half fructose)
Honey
Maple syrup
Fructose is only metabolized in the liver, and its byproduct is uric acid. High levels of uric acid signal to the body to make and store fat reinforcing the fat storage cycle.
Think about animals in the wild that live more according to the laws of nature like our ancestors did, as opposed to us, in modern society, with ready access to food and water. Bears, for instance, before the winter when the weather is good and there is an abundance of food available, will eat all day and all night (it’s estimated that they can eat about 90lbs or 20,000 calories per day, gaining 3lbs daily before hibernation!). The ripe fruits available–berries, in their habitat–are a favorite source of calories providing large amounts of fructose.
When fat storage is activated in the presence of large amounts of fructose, various things happen that fall into the category of what we know as metabolic syndrome, including:
Hunger will be activated by releasing large amounts of the hormone ghrelin, and becoming resistant to the hormone that signals satiation, leptin, to drive the animal to eat more, and store more while food is available.
Weight gain. Excess calories are stored as triglycerides in fat cells, in the liver, and in the blood to provide energy when food will be unavailable. The extra fat will also provide insulation during cold weather.
The slowing of metabolism and physical activity helps the animal conserve energy and prolong stores of fat. When animals go into hibernation, they drop their body temperature to slow their heart rate, breathing, and metabolism even more. In that way they can burn excess fat very slowly to get them through cold and food-scarce times.
Insulin resistance. Insulin is the hormone secreted by the pancreas in the presence of food, and controls the amount of glucose in the bloodstream at any given moment. It is necessary for the uptake of glucose in the muscle, liver, and fat. When the survival mechanism is activated, insulin resistance becomes a way of directing glucose to the brain as opposed to the muscles or liver in preparation for times of food scarcity.
High blood pressure. While the reasons why this happens are not yet fully understood, there’s research that shows that high levels of uric acid (the by-product of fructose) results in low-grade inflammation of the kidneys, which causes high blood pressure. This low-grade inflammation causes the kidneys to retain salt, which is helpful during times of dehydration (again, my previous post on salt goes into details about this).
As you can see, weight gain and fat storage in wild animals, and presumably in our ancestors, was beneficial. It was a type of “savings account.” While useful for us in the ancient world, it’s hardly useful for most in today’s world. In animals, the excess fat serves a purpose and is utilized for a period of time, but stores are eventually depleted and the animal returns to its previous weight and health state.
For us, modern humans, the fat storage signal is easily activated when eating processed foods that are loaded with sugar, and especially high fructose corn syrup, plus sodium—the perfect weight-gaining combo. When this switch is activated and maintained, the result is chronic metabolic syndrome.
Fructose, then, is key to enabling the fat storage signal and the cascade of events that come with it that are at the root of many chronic diseases we see today– type 2 diabetes, hypertension, heart disease, and obesity.
Note: fruit is a nutritious food, and I’m not saying that you shouldn’t eat it. A piece or two of fruit will provide negligible amounts of fructose. However juicing fruits will provide concentrated amounts that if consumed regularly, may lead to activating the fat storage signal.
Fat-burning switch
The good news is that on the other side of the fat storage activation mechanism is a fat burning one. The one that signals to the body that food is abundant, that there’s no need to store fat or increase the production of blood sugar. It involves a molecule called AMPK, short for adenosine monophosphate-activated protein kinase –a mouthful! I’ll leave the details of this one for another post, but I wanted to mention that there are ways to activate AMPK and in turn the fat burning signal. Some of these involve keeping blood sugar and uric acid levels down through exercise, certain foods (specific supplements can be helpful), and fasting.
What about dietary fat? Do high amounts of fat also get stored in the fuel “savings account”?
They can. If the fat storage signal has been activated by consuming large amounts of fructose and salty foods (both concentrated especially in processed food), consuming large amounts of fat will lead to even more rapid weight gain.
However, if your diet is low in fructose, relatively low to moderate carbohydrate and you hydrate well, it is less likely that the survival “switch” will be turned on. In that case, consuming foods high in fat will not lead to weight gain. Conversely, if you follow a low-fat diet to lose weight, the only way it will work is if you also restrict calories and stay clear of high fructose foods.
Fat IS GOOD for you!
Dietary fat is in fact essential for many different functions, and plays a role in gut, skin, immune, nerve, brain and reproductive health. It is necessary for proper absorption of fat-soluble vitamins: D, E, K, and A, and is needed for the production of sex hormones.
Some ways you can tell that you’re not getting enough fat is if you have dry, itchy skin, brittle nails, and little bumps in the back of your arms. For women, it can lead to amenorrhea–the absence of the menstrual cycle and affect fertility. Other conditions associated particularly with Omega 3 fatty acid deficiency include memory problems, mood disorders including anxiety and depression, and stiff, achy joints.
Different types of fat to help you choose wisely.
Saturated fat is found in animal foods including full fat dairy (butter, cheese, yogurt), red meats, tallow, and lard, and also in coconut and palm oil. It’s stable when heated and doesn’t convert into oxidized fats, which are damaging. These are good fats to cook with.
These are also the fats that have been linked with raising LDL cholesterol and a higher risk of coronary artery disease. Some of us have a genetic predisposition to higher levels of this type of cholesterol, and most doctors recommend limiting this type of fat to 10% or less of daily calories, especially if you’re genetically predisposed..
Monounsaturated fat is the type associated with lowering the risk of heart disease. Found in olive oil, avocados, and walnuts.. These fats are more vulnerable to oxidation and are best consumed cold (especially cold-pressed oils). While other oils, like canola and peanut oil are also monounsaturated fats, they are highly refined and become oxidized in the process, making them lose their health promoting qualities.
Polyunsaturated fats include:
Omega-3 fatty acids are found in oily fish like salmon, sardines, mackerel, and tuna, wild game, eggs from grass-eating chickens, walnuts, flaxseeds, hempseeds, chia seeds, and algae. These fatty acids have been widely researched and shown to have anti-inflammatory properties, and to be especially helpful for people with chronic inflammatory diseases. They are also known to support brain function. Interestingly, they can actually block some of the negative effects of fructose! Omega 3s are great fats to consume on a regular basis. There are three main types: ALA, EPA & DHA. The vegetarian sources-flax, walnuts, hempseeds & chia- of omega 3s contain ALA; our bodies must convert ALA to more usable forms of omega 3s: EPA & DHA. Because it’s difficult to manufacture optimal levels of EPA & DHA from ALA, it’s more efficient to get them directly from animal sources (or supplement with a fish oil).
Omega-6 fatty acids are found in many foods including poultry, nuts, seeds, and in oils like corn, soybean, safflower and sunflower. Types of omega 6s include LA, linoleic acid, AA, arachidonic acid, and GLA, gamma-linoleic acid. Research on these fatty acids is mixed, some showing benefits and others showing that they are inflammatory. GLA is one that has been found to reduce inflammation. It can be found in borage oil, primrose oil, black currant oil, and hemp oil.
Current dietary advice focuses on the ratio, favoring consumption of a higher Omega 3 to Omega 6. In general, this is easily done by choosing fruit oils like olive, avocado, and to a lesser extent coconut, over seed, grain and bean oils like safflower, sunflower, grapeseed, corn, soybean, etc.
Learn your ratios
Pro-tip: Something that I have found very helpful to have a better idea of the types of fat I’m consuming, is to occasionally record my food intake on an app like Cronometer or similar. It can be very helpful in finding what your Omega 3 to 6 ratio is, and how you might want to modify it.
Fatty Recipe
One of my favorite fatty condiments is homemade mayonnaise—a super easy and delicious pairing for vegetables rich in fat-soluble vitamins. It not only enhances their flavor but also their nutrient absorption. Find my recipe for homemade mayonnaise here.
REFERENCES
Johnson, Richard J., 2022. Nature Wants Us to Be Fat. BanBella Books.
Perlmutter, David & Loberg, Kristin, 2022. Drop Acid. Little, Brown Spark
Wahls, Terry & Adamson, Eve, 2014, 2020. The Wahls Protocol, A Radical New Way to Treat All Chronic Autoimmune Conditions Using Paleo Principles. Penguin Random House.
Murray, Bob & Rosenbloom, Christine, 2018. Fundamentals of Glycogen Metabolism for Coaches and Athletes. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6019055/
Purohit, Dhru. This Miracle Nutrient Will Add 5 Years to Your Life. The Dhru Purohit Podcast, Episode #246.