DIETARY FAT’S ROLES IN THE BODY
Dietary fats (also called “lipids”) are essential for all metabolic functioning and play a primary role in
· cell membrane structure and functioning
· neurological functioning
· endocrine and hormonal functioning
· the transport of fat-soluble vitamins (A, D, E and K)
· skin health and
As far as being a source of energy, fat (both dietary fat and adipose tissue/stored fat) is generally a secondary source, ahead of protein (normally a tertiary source of energy) but behind carbs/glucose (normally a primary source of energy). When carbohydrate intake is sufficiently low, the body will increase its utilization of triglycerides (composed of a glycerol molecule and 3 fatty acids) and free fatty acids for cellular fuel. Some fats are also broken down into ketones through a process called ketosis. The body will also use these ketones for energy/fuel. The result of this physical state is often a reduction in body fat, which is one of the primary goals of low carb/ketogenic diets (ex. Atkins, Keto, etc.).
DIETARY FAT DAILY RECOMMENDATIONS
The USDA doesn’t offer recommendations for dietary fat in grams per day but does through its convoluted caloric guidelines. For men 18 years of age and older, the USDA’s recommended caloric range is 2000-3200 cals/day. For women it’s 1600-2400 cals/day. For dietary fat the recommendation is 20-35% of daily calories from fat.
So now we have to do some math to convert these numbers into grams per day. For men, on the low end we’re looking at 20% of 2000 cals, which equals 400 cals from fat. Then we divide this by 9 (remember, 9 cals per gram for fat) to arrive at 44, which is to say 44 grams of fat per day. Get it? Instead of doing that again, I’ll just list the ranges we arrive at below…
Fat guidelines, for men: 44g to 124g a day
Fat guidelines, for women: 36g to 93g a day
So that’s the government’s word on it. [1-4]
But what do the so-called experts say? Well, that definitely depends on the expert, and what sort of attitude that expert has toward dietary fats. On one side we have the “lower-fat-is-better” crowd. This would include many academic, governmental and non-governmental dietary “experts” from the 1970s up until recently. I say recently because many of these so called “experts” are recanting (at least slightly) from their previous “lower-fat-diets-are-healthier” stance. On the other side of the spectrum we have advocates for ketogenic and Atkins-type diets, where high fat intake is often encouraged.
The U.S. government, backed by poor science produced by biased researchers, issued guidelines in the late 1970s that promoted a low fat, low cholesterol, low salt, high starch, high carbohydrate diet for optimal health. These guidelines had (and still have) a profound influence on the dietary habits of many Americans. And what concurrent developments have we witnessed on the American health landscape over the past 40 years?
ADULT OBESITY: A doubling of obesity rates among adults.
CHILDHOOD OBESITY: A tripling of obesity rates among children.
DIABETES: A quadrupling of mortality rates arising from diabetes.
ALZHEIMER’S: A 50-90% increase in the mortality rates for Alzheimer’s from 2000-2015.
And this is not to mention the wide-spread prevalence of inflammatory conditions (ex. arthritis, fibromyalgia, etc.) and diseases related to fat soluble vitamin deficiencies (vitamins A, D, E and K), which includes autoimmune conditions, insomnia and osteoporosis.
While the reasons for these increases are, of course. multi-factorial, a very strong case can be made that one of the driving factors (perhaps the driving factor) for the increase in these degenerative conditions has been dietary habits- specifically the widespread adoption of a low fat, high carbohydrate eating pattern for many Americans. [5-14]
So with all of that in mind we’re going to ignore the low-fat advocates and instead look at what others have to say, including those that advocate for a ketogenic diet (higher fat, low carb). Unfortunately, many experts here still base their recommendations through the prism (prison?) of overall caloric recommendations from the USDA. For a ketogenic diet, it’s generally recommended the dieter aim for 60-80% of daily calories from fat. [15-17]
Here’s how that breaks down in grams…
Recommended daily fat intake, for men:
133g (60% fat, 2000 cal diet) to 284g (80% fat, 3200 cal diet)
Recommended daily fat intake, for women:
107g (60% fat, 1600 cal diet) to 213g (80% fat, 2400 cal diet)
Now those ranges are general ranges and don’t take into account some other fairly significant factors. There are free online “keto calculators” that can give more customized macronutrient recommendations for those interested. A few of those websites are listed below…
BASING TARGET DAILY DIETARY FAT
INTAKE OFF OF IDEAL BODYWEIGHT
I’m a little surprised I haven’t come across anyone giving daily fatty acid intake recommendations in the way that dietary amino acids (proteins) are often recommended- based off a person’s bodyweight (or lean mass or ideal bodyweight).
In the section of dietary proteins I suggest using 0.8-1.0g per pound of ideal bodyweight, per day, to calculate target protein intake guidelines. So in the spirit of standardization and uniformity I want to do the same for dietary fats. There’s a problem, however. On one hand it’s clear that the USDA recommendations often err on the low side (36-124g dietary fat per day for adults). On the other hand, some advocates for the high fat keto approach err on the high side (107-284g dietary fats per day for adults). A diet too high in dietary fat can overwhelm the liver and gallbladder (both of which are needed to produce enough bile to break down/emulsify fat). And considering that 75-100 MILLION Americans currently suffer from NAFLD (non alcoholic fatty liver disease), a very high fat diet is likely contraindicated for a large percentage of Americans. 
Considering that, I created a formula which takes into account both the USDA’s recommended caloric ranges for adults (1600-3200 cals/day) and some of the prevailing wisdom for fat recommendations on a ketogenic diet. That formula is 0.5-0.8g of dietary fat per pound of ideal body weight, per day. I’ve listed some examples of how this breaks down for different ideal body weights below…
As with protein, I’d recommend setting your initial daily fat intake goal on the more conservative side, at the lower end of the ranges listed above. Again, those suffering from certain digestive system conditions (including certain liver and/or gallbladder issues) may have trouble properly digesting and/or absorbing fats and may be better served by lowering fat intake to a level more easily handled by a compromised digestive system. And as I mentioned with dietary protein, obviously those utilizing intermittent fasting (particularly those using longer fasting windows) will periodically have days with much lower (or even no) caloric intake from dietary fat.
"SATURATING" YOUR ARTERIES WITH FAT, RIGHT?
Dietary fatty acid molecules are made up of oxygen, hydrogen and carbon, with the carbon chain generally numbering from 4 to 28. These fatty acids can be divided into two groups- saturated and unsaturated. Unsaturated fat can further be broken down into either monounsaturated or polyunsaturated types.
Foods containing high amounts of saturated fat include coconut oil, coconut milk, grass-fed butter, cream, whole milk dairy products, dark chocolate, egg yolks, non-lean cuts of beef, dark meat chicken and wild caught salmon. But don’t make the mistake of thinking that a high saturated fat intake will “saturate your arteries with fat” or otherwise predispose you to cardiovascular disease. Saturated is merely a chemical term and indicates the “saturated” nature of the carbon chains of the fatty acid molecule (they’re completely filled with hydrogen atoms, which actually makes the fat more stable, and also solid at room temperature). 
ESSENTIAL FATTY ACIDS (EFA’S)
Of the many fatty acids, only two have been deemed essential fatty acids (EFAs): an omega 6 fatty acid (linoleic acid/LA) and an omega 3 fatty acid (alpha linolenic acid/ALA). Both EFAs are unsaturated fatty acids. Most of the research on EFAs focuses on omega 3s for a couple reasons- first, omega 3 deficiency is relatively common compared to omega 6 deficiency, and second, omega 3s tend to have more dramatic therapeutic effects on the body than omega 6s, in general. Alpha linolenic acid (ALA) is a precursor to two other notable omega 3s- EPA and DHA. These two long-chain fatty acids are known for supporting neurological, eye, skin and cardiovascular health, and also have been shown to have notable anti-inflammatory effects on the body. While EPA and DHA can be synthesized from ALA by the body, due to a very low conversion efficiency it’s generally recommended that individuals consider utilizing supplements (such as concentrated fish oils high in EPA and DHA) in order to obtain therapeutic amounts. Healthy foods that are high in omega 6 EFAs include unrefined sunflower oil, unrefined safflower oil, sunflower seeds and in supplements like evening primrose oil. [20-22]
And then there’s cholesterol. Cholesterol is part of a group of naturally occurring unsaturated steroid alcohols called sterols. These waxy, fat-like substances include sterols found in plants called phytosterols (ex. campesterol, sitosterol, stigmasterol) and sterols found in animals called zoosterols (of which cholesterol is the most well-known). Cholesterol is used by the body for a whole host of essential metabolic functions, including:
· building and maintaining cell membranes and cellular integrity
· proper brain and neurological functioning (the brain holds ~25% of the cholesterol in your body)
· the production of hormones like serotonin and sex hormones progesterone, estrogen and testosterone
· acting as a precursor to bile acids (which are required for proper fat metabolism and the absorption of fat soluble vitamins)
· the production of vitamin D (synthesized from 7-dehydro-cholesterol)
Cholesterol is found in high amounts in foods like beef liver, egg yolks, butter and cream, and is also present in notable amounts in dark meat poultry, red meat, wild-caught fatty fish and whole milk dairy products. Dietary cholesterol, however, only accounts for around 25% of the circulating cholesterol in the body and blood. So where does the majority of circulating cholesterol come from? While every cell can produce cholesterol, it’s the liver that produces the most- around 75% of the circulating cholesterol in your body (which is usually 1000-1500mg a day).
So why has cholesterol been vilified for decades amongst conventional medical circles and the general public? A large part of the reason had to do with the flawed and cherry-picked research of an atheist scientist named Ancel Keys. Keys’ work, in particular his Seven Countries Study (1958) tried to positively correlate consumption of dietary saturated fat and cholesterol with increased rates of cardiovascular disease (what is known as “The Lipid Hypothesis”). His work (and his relentless and at times vicious advocacy of it) even landed him on the cover of Time magazine in 1961. The witch hunt against cholesterol (and saturated fat, and sodium) which started in the 1950s ramped up through the 60s and 70s- and the effects were clearly and dramatically seen in the dietary choices of Americans. From the mid-1950s to the mid-1970s, per capita butter consumption fell by over half. During the same time egg consumption fell by over a quarter. Consumption of margarine (first created in 1869 and generally comprised of cottonseed, soybean and other refined oils) doubled from 1950-1972.
The government officially gave The Lipid Hypothesis the rubber stamp of approval with the USDA’s Dietary Guidelines for Americans in 1980. In those guidelines, the USDA wrongly targeted cholesterol (and saturated fat, and sodium) as primary culprits in conditions like heart disease and obesity. Even Time magazine jumped in on the hysteria with its famous (infamous?) 1984 cover featuring a frowning eggs and bacon. All of this contributed to continued reductions in the amount of total dietary fat, saturated fat and cholesterol consumed by Americans during the 1980s, 1990s and 2000s, along with accompanying increases in carbohydrate consumption.
Seeing an opportunity to make millions (and billions) of dollars, the pharmaceutical industry jumped on the bandwagon, and began developing statins (a type of cholesterol-reducing drug) in the 1970s (Merck’s lovastatin was really the first), and then aggressively marketing those same statins from the 1980s right up to today. Once statins became a widespread and accepted first line of defense against CVD by the medical majority, sales exploded. Along the way the public got miseducated on LDL (so-called “bad cholesterol”) and HDL (so-called “good cholesterol”). Let’s take a look at the truth…
Cholesterol is fat soluble and, therefore, doesn’t mix well with our watery blood, so it must be transported through the body with the help of specialized carriers called lipoproteins. These lipoproteins are generally classified as one of two types- LDL (low density lipoproteins) and HDL (high density lipoproteins). In conventional circles LDL has come to be known as “bad cholesterol” and HDL as “good cholesterol.” This is incorrect, and an over simplification. Cholesterol is cholesterol. There is no “bad” or “good” cholesterol. LDL cholesterol plays a vital role in a host of essential bodily functions (see above). However (and it’s a big however), OXIDIZED LDL can build up in the blood vessels (increasing the risk of heart attack or stroke) when the body is in a disease state. The real root causes of this over accumulation of “sticky”, oxidized LDL tend to center around things like…
1. out of control blood sugar (from excessive carb intake and/or pancreatic dysfunction)
2. other nutrient imbalances (deficiencies in EFAs and/or antioxidants [vitamin C, E, CoQ10, etc.])
3. systemic infection
4. excessive and chronic inflammation (which itself can be caused by a host of things, including hormonal imbalances, stress, and the factors already mentioned).
As many others have pointed out, cholesterol has been vilified like so many others have been vilified- because of its presence at the scene of the crime. Oxidized LDL is often present in significant amounts in arterial plaque (as are platelets, calcium and fibrin). As we’ve already stated, one of cholesterol’s primary roles in the body is supporting cellular and tissue integrity. Stated simply, when LDL builds up on the arterial wall, it’s doing its job- supporting tissue integrity. The arterial walls are being damaged by one or more of the root causes listed above (excessive blood sugar, nutrient imbalances, systemic infection, etc.). Cholesterol, carried by LDL, is trying to “patch up” damaged and degenerating vascular tissue. Cholesterol is the main culprit in cardiovascular disease like cops are the main culprit in crime scenes, or firemen are the main culprit at house fires. Correlation doesn’t equal causation.
Additionally, numerous studies have refuted the idea of cholesterol being a causative factor in heart disease. In 2012 researchers examined more than 52,000 adults ages 20-74 and concluded that women with HIGHER cholesterol levels (>270mg/dl) had a 28% LOWER mortality risk than women with LOW cholesterol (<183mg/dl).
A PARADIGM SHIFT
TOWARD SATURATED FATS & CHOLESTEROL?
While there have always been dissenters to The Lipid Hypothesis, thankfully a widespread paradigm shift has begun. First was a 2014 meta-analysis from 32 observational studies (over half a million participants in total) that looked at dietary fatty acid intake and its effect on cardiovascular disease. The conclusion? “Evidence does not clearly support cardiovascular guidelines that encourage… low consumption of total saturated fats.” And then there was the 2014 NY Times article “Butter is Back” by Mark Bittman. And then Time Magazine’s 2014 cover titled “Eat Butter.” And finally, the USDA’s 2015 National Dietary Guidelines, which for the first time in 35 YEARS dropped cholesterol as a “nutrient of concern”, removing the recommendation to limit daily consumption to 300mg. [23-27]
[Other healthy sources of fats not mentioned above include virgin cod liver oil, extra virgin olive oil, avocados, and small amounts of most nuts and seeds.]
Dietary fat is an essential macronutrient and plays a critical role in neurological and brain health, endocrine and hormonal functioning, skin health, and the transport of fat soluble vitamins. Dietary fat (along with adipose tissue) can be used as fuel (“energy”), especially when the body is in a ketogenic state (resulting from reduced carbohydrate intake). While it’s not quite as simple as the statement that follows, the general principle holds true- consuming dietary fat does not make people fat. Said another way, dietary fat is a relatively minor player in the obesity epidemic when compared to carbohydrates (particularly cane sugar, refined sweeteners and refined complete carbohydrates). Additionally, “The Lipid Hypothesis” (a theory that high dietary fat, saturated fat and cholesterol intake are positively correlated with cardiovascular disease rates) has been proven false by numerous studies and meta-analyses. Consumption of a certain amount of healthy fat (typically 80-160g/day, or sometimes more depending on the individual) can actually help an individual to lose unwanted weight, maintain a healthy weight, and support cardiovascular health. Additionally, saturated fat, cholesterol and even some natural trans fats (such as CLA) can be incredibly beneficial to overall health when consumed from certain natural sources.
18 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5794571/ (75-100 million Americans with NAFLD)