Making Friends With Fat
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People often laugh when I ask them if the food they love loves them back. We don’t tend to think about whether food is friendly or not. A friendship is a relationship, and we certainly have relationships with food, which may endure for decades or a lifetime. But are these foods good company after we swallow them? Do they return the affection we feel for them – do they make us feel good at all? A friend is loyal and well-meaning, someone with whom we share interests and core values. Do the foods we eat act in our best interest? Do they treat us well in return for our trust in their value?
The definitions of friend shown above apply to food as well – terms such as “mutual affection”, “a supporter of a cause” (your health), “a person who is not an enemy” (foods that do no harm), and “a familiar or helpful thing” (comfort foods, healing foods). Thankfully, the last definition about social media does not directly apply – we don’t eat food online, though posted content certainly shapes our experience and informs our knowledge and choices of food.
Fat can be either friend or foe. Information and beliefs about fat are complex, controversial, contradictory, and confusing – enough to make people throw up their hands and give up on trying to figure out their choices – or to take sides randomly and act out of decision fatigue. Some people say fat is good for you; others say it only causes weight gain and heart disease. Studies may be found that support either view – and may be designed to do so, according to the desired outcome of the sponsor. Which findings are outdated, and which can we trust? How do we know what to believe about fat?
What do we even mean by fat – is it the fat in our meals that matters, or the lipids in our bloodstream? Is it the fat that trims a steak or that laces our liver? What makes us fat, and which fats are healthy?
In this article, we’ll examine both dietary fats and body fat – different types that are healthy and harmful according to current nutrition science, and how they affect our metabolism and long term health. But first let’s briefly trace our commonly-held beliefs about fat back to their origins, and see where all this confusion began.
In 1958, a long-term observational study in seven different countries was launched to investigate the role of diet in cardiovascular disease. Led by a physiologist named Ancel Keys, the Seven Countries Study focused on saturated fat and lasted for twenty years. In the 1960s, the study led to a major pivot in U.S. dietary guidelines, and the war on fat began. Americans were advised to avoid fat in general, especially saturated fat and dietary cholesterol. Low-fat products were aggressively marketed by the food industry, and began crowding supermarket shelves with the promise that reducing dietary fat would also reduce the risk of heart attack, cardiovascular disease, and obesity.
In 2016, a paper in JAMA Internal Medicine1 revealed that in 1965, the Sugar Research Foundation (now the Sugar Association), based partly on Keys’ work and the consensus of the time, had paid Harvard researchers $6,500 (equivalent to roughly $60,000 today) to publish a review article in the New England Journal of Medicine that downplayed sugar’s role in heart disease and emphasized dietary fat and cholesterol as the primary culprits. The sugar industry’s financial backing was not disclosed in the publication. This concealed conflict of interest is considered unethical today.
So fat became the villain, while the role of sugar in obesity, diabetes, and cardiovascular disease was ignored. Calories once derived from fat were replaced with refined sugars and starches. More than half a century later, the results are clear: obesity, type 2 diabetes, metabolic syndrome (including heart disease), cancer, and chronic disease have all significantly increased. Diabetes has shown an estimated 4 to 8-fold increase between 1958 and 2000,2 while obesity has nearly tripled.3
Years later, Keys retracted the findings of his study, but this was not released to the public. Numerous researchers have concurred since then. A large review of the most rigorous research on saturated fat published in the Annals of Internal Medicine found no link between saturated fat and heart disease, and concluded that “the current dietary guidelines that tell us to avoid saturated fat and increase refined vegetable oils are not supported by scientific evidence.”4
It’s not uncommon for studies to be overturned – but changing public opinion is another matter. For progressive nutritionists, the idea that dietary fat is dangerous is long outdated. But among mainstream physicians – who receive little to no nutrition education – and the general public, fat is still frightening. So I wasn’t surprised when recently, a friend emailed to ask why I recommend full-fat dairy. Following common recommendations for so-called health-conscious consumers, he was used to buying low-fat or non-fat yogurt, milk, cheese, sour cream, and ice cream – as well as non-dairy low-fat products such as salad dressings, plant-based beverages, protein drinks, and more. Isn’t low-fat safer, he wanted to know?
Once again, I was struck by this intractable fear of fat that still grips our society. Yet even common sense tells us it’s baseless, as fat has been sought after and consumed by every civilization on the planet. We’ve co-evolved along with olives and nuts, the milk of grazing animals, poultry and fish . . . these are friendly fats, if harvested from clean sources. Were our ancestors misguided? Let’s bring ourselves up to date.
Dietary Fat
When it comes to food, what do we mean by friendly fat? That depends on the source of the fat, what form it’s in, how it’s prepared, and the context in which it’s eaten. Healthy fat is essential for human health – but it’s important to remember that not everyone metabolizes fat the same way. Europeans are known to suffer fewer ill effects from eating saturated fat, because they typically do not eat it with ultra-processed foods that are high in calories, salt, refined carbohydrates, and inflammatory fats. Saturated fat as part of an overall healthy diet of fresh fruits and vegetables, whole grains, herbs and spices has a completely different effect than saturated fat combined with sugar, refined carbs, chemical additives, bleached salt, and industrial oils.
Among the fats we find in foods, these are your best buddies:
• Essential fatty acids
Odd-chain essential fatty acids (so named for the position of the first double bond in long-chain lipids) such as omega-3, omega-7, omega-9, and C15 – are found in small, oily fish; certain forms of algae (of uncertain bioavailability); pasture-raised fermented dairy; macadamia nuts (omega-7), pasture-raised butter, and more. Omega-3 EFAs are most well-known; these are anti-inflammatory, and contain DHA and EPA, which are crucial for cell membrane integrity and brain health.
Omega-6 EFAs are pro-inflammatory; these even-chain fatty acids are found in vegetable and seed oils, all processed and packaged snack foods, and most restaurant foods. If omega-6 EFAs dominate your diet, they will cancel out the benefit of omega-3s. Think about the ratio of these fats in your diet. Are you eating the ones that serve your health? Like people who seem friendly on the outside but don’t act that way on the inside, omega-6 fats might taste good in crispy French fries or an enchilada – but inside your body, they’re silently doing harm.
• Polyunsaturated fats
Polyunsaturated fats are familiar friends in the form of whole nuts and seeds. PUFAs (polyunsaturated fatty acids) may also be extracted from soybeans, corn, rapeseed (canola), sunflower seeds, grape seeds or sesame seeds by means of pressure or chemical solvents – which changes them completely. These industrially-produced vegetable and seed oils are fragile and chemically unstable; they quickly degrade, and turn rancid especially when exposed to high heat. They are the reason why most Americans have far too much omega-6 EFAs in their bodies – as much as 32 times the amount consumed by our ancestors, who did not have access to these oils, and could only eat seeds and beans in moderation. In their whole form, nuts and seeds contains fiber, phytates, other forms of fat, and phytochemicals that act as cofactors in mitigating the inflammatory effects of the isolated oil. These whole forms are your friends; the factory-made fellows, sadly, are not. See below for more about industrial oils.
• Monounsaturated fats
Monounsaturated fats (MUFAs) have been our allies for thousands of years, and were essential to the lives of our ancestors in the form of olive oil. Cacao beans also contain both MUFAs and saturated fat. MUFAs are known to raise HDL (so-called "good" cholesterol), lower LDL ("bad" cholesterol), improve insulin sensitivity, reduce oxidative stress and inflammation, and support healthy blood vessels and heart function.
Beneficial plant-based oils come from fruits such as avocado, olive, and coconut; and nut oils such as walnut and almond. Organic sesame oil, sesame butter (tahini), and nut butters are also good choices, but tend to be expensive. I do not recommend peanuts or peanut oil: see my article Nutrition In A Nutshell for more on this subject. Beware of fraudulent olive oil and avocado oil. Do your research, and look for certifications of authenticity.
Animal fats such as pasture-raised beef tallow, goose fat, butter, and ghee are all heat-tolerant fats full of vital nutrients. Be your own best friend, and prioritize products made from pasture-raised animals. Butter from factory-farmed cows does not have the same nutritional profile or benefits as butter from a grass-fed cow.
Linoleic acid or alphalinoleic acid (ALA) and gamma-linoleic acid (GLA) are plant-based EFAs found in borage seeds, evening primrose seeds, black currant seeds, hemp seeds, flax seeds, and chia seeds. ALA is a precursor for DHA and EPA, and is converted in the liver to produce these animal-based essential fatty acids. However, only 5-10% of ALA is converted – therefore plant-based omega-3s are not sufficient to provide enough of this critical fat to fulfill your body’s needs. Algae-based supplements claim to fill this gap. I’m skeptical.
• Conjugated Linoleic Acid
Conjugated linoleic acid (CLA) is a polyunsaturated omega-6 fat that is found only in the meat and dairy of grass-fed animals. In the magic rumens of grazing goats, sheep, and cows, the many plants they eat together with insects and soil are transformed into healthy fats. CLA has been shown to reduce body fat mass (especially abdominal fat) and help preserve lean muscle. It may improve lipid metabolism and reduce arterial plaque. Your pasture-raised pals even help your own gut produce cardioprotective and cancer-preventing postbiotics. More research is needed, but this much is clear: CLA from pasture-raised ruminants is your friend.
Together, all these fats work to help your cells live up to their full potential. These are the kinds of friends you want. Optimal health depends on friendly fat!
What about unfriendly fats? These include artificial trans fats, industrial oils, rancid fats, and fats that may be harboring toxins. These are the fats to avoid. Whether you like them or not, they’re NOT your friend. We all know what it’s like to find someone appealing, only to discover with time that they’re simply not good for us. The harm they do may be hidden, or hiding in plain sight. Let’s zoom out and see how these fats really behave in your body.
• Trans fats
Also known as hydrogenated oils, these artificially-produced fats are solid at room temperature, mimic the consistency of butter in baked goods, pizza dough, and pie crusts; make non-dairy creamers thicker and smoother; provide structure to ultra-processed foods; and are more shelf-stable than natural fats. Trans fats are strongly linked with chronic inflammation, coronary artery disease, and cognitive impairment and decline. Estimates indicate they were responsible for up to 500,000 deaths annually worldwide, with some studies suggesting up to 250,000 heart attacks and 50,000 deaths in the U.S. alone per year before they were finally banned in many countries, including the U.S., Canada, and much of Europe.5 Today, trans fats are still allowed in processed foods as long as it’s below a certain percent – and the front of the package may still say “no trans fats.” Check the nutrient facts on the back label to be sure they don’t contain trans fats, which may be cloaked in such deceptive terms as “vegetable shortening,” or “partially hydrogenated” oils. Trans fats are your enemies, to be avoided completely.
It should be noted that a very small amount of naturally-occurring trans fats may be found in some animal foods. These do not behave the same way as artificial trans fats, and they are not harmful.
• Industrial oils
It truly amazes me that commercial labels on industrially-produced vegetable and seed oils still say “heart healthy!”, because they don’t contain saturated fat. Nothing could be further from the truth. On the contrary, industrial oils contribute to chronic inflammation, including in the linings of your blood vessels, which leads to heart disease. Machine-driven agricultural practices that produce these oils also degrade soil, deprive wildlife of habitat, and damage the ecosystem with large-scale monoculture.
It may be hard to imagine life without these common staples of our supermarket shelves, but large-scale industrial agriculture only took hold about a century ago. Up until 1990, McDonalds was still using beef tallow to make french fries. Beef tallow is highly heat tolerant and resists oxidation. But in response to consumer fears about saturated fat, McDonalds switched to vegetable oil: a blend of soybean, corn, and cottonseed oil – the most toxic, inflammatory, chemical-laced oils on the planet. Used repeatedly at high temperatures, these rancid oils may contribute to all kinds of chronic, inflammatory conditions. Fortunately, there’s a rising tide of awareness about vegetable and seed oils (check out the app “Seed Oil Scout”). Unfortunately, food manufacturers and restaurants continue to use them, because thanks to government subsidies, they’re a whole lot cheaper. These products are not consumer-friendly.
• Rancid fats
Oils that are liquid at room temperature are generally more vulnerable to oxidation, and turn rancid with time. Oils with low smoking points turn rancid even faster when cooked at high temperatures or used repeatedly (a common practice in restaurants). Find the smoking points of cooking oils here.
• Toxic fats
In both plants and animals, fats act as storage molecules. They’re meant to store energy, but may also store toxins contained in the nutrients they absorb. Thus the expression “You are what you eat – and what your food eats.” The fats in large, predatory fish may harbor mercury that is bioaccumulated from the aquatic food chain. Factory-farmed animals may harbor artificial hormones and drugs. Coffee and cacao beans may accumulate heavy metals from soils that do not contain healthy minerals. Minerals compete for uptake, both in soil and in your body – once ingested, these heavy metals may actually displace the minerals you need for healthy bones. Even the bran and the germ of rice grains, which are rich in lipids and essential fats, absorb arsenic from contaminated rice paddies.
Body Fat
Within the body, fat shows up in different forms, both healthy and unhealthy. Let’s take a closer look at each one:
• Cholesterol
Cholesterol plays numerous vital roles within the body, and is essential for human health. It’s the building block for steroid hormones, including estrogen, testosterone, cortisol, and aldosterone (which regulates salt balance). Sunlight converts cholesterol in your skin into vitamin D3, which is vital for bone health, immunity, and hormone regulation. The liver uses cholesterol to make bile acids, which are secreted into the gut to break down dietary fats; and to absorb fat-soluble vitamins A, D, E, and K, as well as folate, magnesium, and more. Cholesterol is also essential for myelin sheath formation (insulation for nerve cells), synapse integrity, and neurotransmitter function, as well as blood vessel repair. Disrupted cholesterol metabolism is linked to neurodegenerative diseases like Alzheimer’s and Parkinson’s. Healthy cholesterol makes a healthy brain!
LDL cholesterol is comprised of several particles that differ in size and density. This a rapidly-evolving field of inquiry and source of controversy. Common blood tests still only test for numbers, failing to take into account the particle size or density, both of which affect how they behave. Not all LDL particles are “bad” – again, it may be friendly (stable and healthy) or unfriendly (oxidized, inflamed, cracked, peeling, or unstable). More nuanced lipid panels such as CardioIQ, Cleveland HeartLab, Boston Heart Diagnostics, and NMR Lipoprofile are available, but may not be covered by insurance. These options continue to evolve.
HDL cholesterol is generally accepted as the “good” cholesterol, which increases with exercise. Here, too, opinions among experts vary, but it is not as controversial as LDL cholesterol.
Triglycerides are the most harmful cholesterol. This unfriendly fat is formed in response to alcohol, sugar, and insulin, and is transported throughout the body. In the bloodstream, triglycerides are an underlying cause of heart disease and pancreatitis. In adipose tissue, they accumulate as belly fat. In the liver, they cause fatty liver disease, which is rapidly on the rise in the United States, largely due to widespread consumption of high fructose corn syrup.6 Non-alcoholic fatty liver disease (NAFLD), once a rarity in our society, now afflicts up to 20% of American teens, who think junk food is their friend no matter how much it abuses them – in some cases to the point of needing a liver transplant.7 Triglycerides also cause obesity, as sugar drives lipogenesis, the process by which the liver transforms sugar into triglycerides. Insulin resistance both increases the formation of fat and impairs its breakdown. Eating saturated fat together with refined carbs – such as the eggs in cheesecake, the cheese in lasagna, or the burger in a bun – also increases the production of triglycerides. A sedentary lifestyle is the icing on this layer cake of unfriendly fats. Fortunately, the reverse is also true: giving up sugar reduces triglycerides and activates fat breakdown; and exercise burns triglycerides as energy.
Once again, the combination of foods and the context in which they’re eaten determine the outcome. Each individual brings a unique combination of factors to the table.
• Visceral fat
Belly fat is all too common as we age, and is generally considered normal and inevitable – but is it? Visceral adipose tissue (VAT) is the only indicator of insulin resistance and systemic inflammation that does not require a blood test. Why? Because belly fat doesn’t just take up space around your middle – it acts as a metabolic factory, pumping out inflammatory cytokines that circulate through your body, causing an overactive immune system that may not function as well when a real infection comes along. Belly fat also creates aromatase, an enzyme that converts testosterone into estrogen in men, resulting in “man boobs” and loss of body hair; and estrogen into testosterone in women, causing excess body hair and polycystic ovarian syndrome (PCOS). In a vicious cycle, belly fat is both created by and contributes to insulin resistance, leading to diabetes and all the negative cascading effects of free radicals and chronic inflammation. A waistline of 35” or less in women and 40” or less in men is considered healthy.
Both liver fat and visceral fat are caused by overconsumption of refined sugars and starches, industrial seed oils, and alcohol. Lower your insulin to let them know they’re not welcome in your inner circle of friends (see my article It’s All About Insulin for more on this subject).
• Subcutaneous fat
Found primarily on the arms, legs, and hips, this form of fat is not harmful. A healthy layer of fat provides important insulation and cushioning for our bones and joints, and also stores energy that may be converted by the liver into glucose as needed, a process known as lipolysis. It may also be accomplished by ketogenesis, the formation of ketone bodies in people who eat a high fat, very low carbohydrate diet – an effective strategy for losing weight as well as normalizing brain chemistry and triggering autophagy, the clearing away of old or damaged cells.
Lipolysis is also triggered by breastfeeding. The high caloric demand of a nursing infant causes excess fat to melt away from the arms, legs, and hips of many new mothers. This is one reason why it’s healthy to gain weight during pregnancy, and to eat plenty of fat while nursing: your body is building up reserves to be drawn upon later.
• Brown fat
This friendly fat deserves its initials BF, because it’s truly your best friend. Brown fat accumulates in the neck or upper back, around the kidneys, spine, and sometimes the heart. Brown fat is metabolically healthy, and readily takes up glucose, helping to stabilize blood glucose levels. It burns triglycerides to produce heat via thermogenesis, by way of a special protein found nowhere else in the body. Brown fat derives its color from high concentrations of iron, which enable thermogenesis in mitochondria-dense brown fat. On a cellular level, this is ideal metabolic functioning.
Brown fat is produced in response to cold exposure (cold showers, ice plunges, or outdoor winter activity), intermittent fasting, or metabolic stimulation (endurance exercise or weight training).8 Curcumin and green tea are also thought to increase brown fat, as well as melatonin, the hormone that induces sleep. Melatonin, in turn, is suppressed by insulin, which is triggered by eating sugar and refined carbs. This is yet another pathway by which sugar impedes the formation of healthy fat.
In making friends with fat, it’s also worth asking if the relationship is mutually beneficial. Are we harming the source of this food by eating it, or supporting its regeneration? Consumers of factory farmed meat and dairy are not only eating unhealthy fat, but also contributing to the suffering of livestock in a life-destroying system. Conversely, eating healthy fats supports the small-scale farms that produce pasture-raised animals with sustainable practices. Organically-produced nuts, seeds, and oils also support earth-friendly agriculture. You can be a good friend to the friends that are good to you, and for you.
So here’s how I answered my friend’s query about low-fat dairy:
1) Lowfat offers no advantage. The idea that dietary fat causes body fat or cholesterol buildup is an outdated myth.
2) The fat in dairy is where the essential fatty acids and most valuable nutrients are found.
3) Lowfat foods are usually altered from their whole-food counterparts through fat removal, substitution, or chemical processing. The process of removing the fat (via centrifuge) can damage fat-soluble vitamins. Because many lowfat dairy products lose their creamy quality, artificial ingredients may be added to restore the texture. Many of these ingredients are harmful.
4) Fat is what makes up our cell membranes, and 60% of our brain. Fat is necessary in order to absorb fat-soluble nutrients, to produce vitamin D, numerous hormones, to preserve healthy cognitive function, and much more.
5) Not all fats are created equal. Fat is best metabolized in the context of an overall healthy diet and lifestyle. It’s the quality, type, and context that matter.
6) Healthy fat speeds up your metabolism and provides long-lasting energy, especially when combined with protein and fiber.
I hope this article helps you feel free to make friends with fat, and to let it provide you with steady sustenance. Good fat is a food you can love – and like a faithful friend, it will surely love you back.
“I count myself in nothing else so happy
As in a soul rememb’ring my good friends.”
— William Shakespeare, Richard II
To your good health –
Yael Bernhard
Certified Integrative Health & Nutrition Coach
Yael Bernhard is a writer, illustrator, book designer and fine art painter with a lifelong passion for nutrition and herbal medicine. She was certified by Duke University as an Integrative Health Coach in 2021 and by Cornell University in Nutrition & Healthy Living in 2022. For information about private health coaching or nutrition programs for schools, please respond directly to this newsletter, or email dyaelbernhard@protonmail.com. Visit her online gallery of illustration, fine art, and children’s books here.
Information in this newsletter is provided for educational – and inspirational – purposes only.
Have you seen my other Substack, Image of the Week? Check it out here, and learn about my illustrations and fine art paintings, and the stories and creative process behind them.
Hyman, Mark, Dr., Food: WTF Should I Eat?, Yellow Kite Books, 2019, p.41
https://pmc.ncbi.nlm.nih.gov/articles/PMC8452362/
The U.S. government subsidizes the corn industry with $4-5 billion in taxpayer money each year. It is not known exactly how much of this supports the production of HFCS, but the net effect is that this sweetener is much cheaper for the food industry than cane sugar and other forms of sucrose.
According to ChatGPT, over 500 liver transplants were performed on American teens with NAFLD between the ages of 13 and 19 in the year 2020. I could not find more current data.
Means, Casey, Dr. and Means, Calley: Good Energy: The Surprising Connection Between Metabolism and Limitless Health, Chapter 8.