Your Guide to Fats

Which food that most people think is “bad” will actually make you slimmer, stronger, and more energetic?


For 50 years, roughly since the end of World War II, we have been told that saturated fat in the diet leads to high cholesterol, which leads to heart disease. We have been told to eat a low fat diet in order to protect our hearts and our waistlines. Let me be clear: this theory is a COMPLETE myth. The Diet-Heart Hypothesis, as it is known, is virtually unfounded by the scientific evidence. Moreover, the advice to eat less saturated fat may be in part responsible for today’s obesity and diabetes epidemics. Let me share some facts with you to make it clear how we all came to such wrongheaded beliefs.

First, let’s recognize that there are many cultures in which people derive most of their calories from fat and have virtually no heart disease. The traditional Inuit, for example, get about 90% of their calories from the fat of seals, whales, and other mammals and fish. The Masai tribe of Africa gets 60-70% of their calories from the fat in meat, blood, and milk. Neither of these cultures evidences heart disease. Clearly, it is possible to eat a high fat diet and not experience heart disease.

Why We Believe Dietary Fat Leads to Heart Disease
So why the persistent belief that fat in the diet leads to heart problems? It all started with a researcher named Ancel Keys. In 1970, he published a now-famous study called the “Seven Countries Study” in which he demonstrated that, across seven countries, the more fat you ate, the more likely you were to die of heart disease.

This study was assumed to be valid. After all, he was a respected researcher with impeccable credentials. His study was picked up by the popular press and he landed on the cover of Time magazine. The Diet-Heart Hypothesis captured the imaginations of the both the public and the scientific communities, and a new dogma was born.

By 1977, there was in fact no good evidence for the Diet-Heart Hypothesis, but the idea had gained acceptance by much of the scientific community, by the government, and by the public.

One January 14, 1977, the Diet-Heart Hypothesis, with its recommendation to eat less fat to protect your heart, was made public policy. Senator George McGovern, head of the Select Committee on Nutrition and Human Needs, announced the publication of the first Dietary Goals for the United States, calling it “the first comprehensive statement by any branch of the Federal Government on risk factors in the American diet.”

According to Gary Taubes, author of Good Calories, Bad Calories, which details the fraud of the Diet-Heart Hypothesis, “Dietary Goals took a grab bag of ambiguous studies and speculation, acknowledged that the claims were scientifically contentious, and then officially bestowed on one interpretation the aura of established fact.” As Jane Brody, a popular and influential columnist for the New York Times wrote in 1981, “the Dietary Goals are beginning to reshape the nutritional philosophy of America, if not yet the eating habits of most Americans.”

The consensus regarding the inception of Dietary Goals is that the committee’s staff, composed primarily of lawyers and ex-journalists, were out to make a name for themselves and were willing to ignore anyone who disagreed with them. A number of prominent investigators testified that the guidelines were premature, if not irresponsible. The American Medical Association said in a letter to the committee that “there is potential for harmful effects for a radical long term dietary change as would occur through the adoption of the proposed national goals.”

The committee wanted to make a mark on public health and wanted to do so regardless of the fact that not all the evidence was in and that the evidence that was in did not support the recommendations. Click on the link below to watch a 3 minute YouTube video of George McGovern’s response to an investigator who disagreed with him:

 The McGovern Report

The REAL Facts of the Diet-Heart Hypothesis: The Evidence You’ve Never Heard
There was a little problem with the science used to support the Diet-Heart Hypothesis, however. First, Keys in fact had reliable data from 22 countries, but he selected the seven countries for analysis that he knew would support his hypothesis. Had he used all the countries or chosen countries at random, as rigorous scientific study would require, there would have been no relation between fat in the diet and death from heart disease.

Click on the link below to watch a 3-minute video on YouTube about how Keys fudged the Seven Countries data:

 Ancel Keys 

But wait! Surely there have been other studies that have shown that eating fat leads to heart disease! Ah, you would think so, wouldn’t you? Millions of dollars have since been pumped into Diet-Heart Hypothesis research, producing famous studies like the Framingham Heart Study and the Tecumseh Community Health Study. Rampant confirmation bias (the propensity of researchers to be so invested in their own theories that they look for evidence that confirms them and ignore evidence that refutes them) among researchers invested in their hypothesis led to selective publication of results.

There were occasional results which lent slight support to the theory and these were taken as compelling evidence and treated as fact. Any disconfirming evidence, such as Frantz’s Minnesota Trial, went unpublished. No one would publish a study that ran contrary to the establishment’s beliefs.

Several studies are often cited as support for the Diet-Heart Hypothesis. Let’s take a look at them and see what the evidence really shows.

First, the Framingham Heart Study was launched in 1950 to observe in a single community the long-term effects of diet and lifestyle on heart disease. 5100 residents of Framingham, Massachusetts were recruited and given physicals every two years to see who got heart disease and who didn’t. In 1961, it initially appeared that the risk of heart disease was higher for those who had high cholesterol than for those who didn’t. This finding is considered one of the “seminal discoveries in heart-disease research” and has been cited as compelling evidence for the idea that eating saturated fat leads to high cholesterol, which lead to heart disease.

However, as more data was accumulated, the researchers came to a very different conclusion. Dr. William Castelli, Director of the Framingham study, stated in 1992:

“In Framingham, Massachusetts, the more saturated fat one ate, the more cholesterol one ate, the more calories one ate, the lower people’s serum cholesterol…we found that the people who ate the most cholesterol, ate the most saturated fat, ate the most calories, weighed the least, and were the most physically active.”

In other words, how much fat and cholesterol you ATE had no impact whatsoever on how much cholesterol you had in your BODY. The Tecumseh Community Health Study, which ran for 10 years, came to the same conclusion. Eating fat did not raise serum cholesterol levels.

Two other massive studies undertaken by the National Heart, Lung, and Blood Institute to resolve the diet-heart controversy also failed to support the Diet-Heart Hypothesis.

The Multiple Risk Factor Intervention Trial (MRFIT), which had participants eat a low-fat, low-cholesterol diet, found that their subjects actually had a slightly higher mortality rate than the control group. This finding was the exact opposite of what researchers expected.

In addition, the LRC Coronary Prevention Trial, which tested cholesterol lowering drugs, found a slight benefit of the drugs on heart disease. This finding was taken as incontrovertible evidence for the Diet-Heart Hypothesis. But of course, the study tested cholesterol-lowering drugs, not a low fat diet, so there was no reason for investigators to use this study as evidence for the benefit of a low fat diet on heart disease. Perhaps the logic was supposed to go like this: cholesterol-lowering drugs have a positive effect on heart disease, therefore less cholesterol in the blood has a positive effect on heart disease, therefore a low fat diet has a positive effect on heart disease. Unfortunately this logic does not hold, as we have already shown that low fat diets do not affect serum cholesterol levels.

Ancel Keys himself later agreed, writing in 1956 that “In the adult man the serum cholesterol level is essentially independent of the cholesterol intake over the whole range of human diets.”

Speaking at the University of Minnesota in 1997, Keys said, “There’s no connection whatsoever between cholesterol in food and cholesterol in blood. And we’ve known that all along. Cholesterol in the diet doesn’t matter at all unless you happen to be a chicken or a rabbit.”

So eating fat doesn’t lead to cholesterol in the body. But what about the second part of the Diet-Heart Hypothesis: that high cholesterol in the body (regardless of its source) leads to heart disease? Isn’t that part true? Isn’t HDL cholesterol good for us and LDL cholesterol bad for us?

Not so fast. It all sounds very simple…but it’s too simple to be true. In fact, there are seven different subclasses of LDL and it is the small dense LDL that is harmful, damaging our arteries and oxidizing quickly. Moreover, research shows that large, buoyant LDL actuallyhelps protect against heart disease.

We now know from research that there are two patterns of cholesterol in the blood, called Pattern A and Pattern B. In Pattern A, small dense LDL (the bad kind) is LOW while large buoyant LDL and HDL (both the good kind) are HIGH. Pattern B is opposite: small dense LDL (bad) is HIGH while large buoyant LDL (bad) is LOW and HDL is LOW. Pattern B is strongly related to heart disease while Pattern A is not. (This finding is probably why some of the research on the Diet-Heart Hypothesis showed a slight correlation between cholesterol and heart disease, such as in the Framingham study mentioned above. But at that time, the fact that there were subclasses of LDL was not yet widely known Unfortunately, these slight correlations were taken as clear support for Key’s hypothesis.)

So simply knowing your overall serum cholesterol, or even knowing your LDL, HDL, and triglycerides, is simply not enough to determine if you are risk for heart disease. You would have to know whether your LDL was mostly small and dense (the bad kind) or if it was mostly large and buoyant (the good kind). You would have to know if you had Pattern A or Pattern B.

Now, here’s where it gets really interesting. First of all, we know that eating dietary fat and cholesterol does not raise serum cholesterol in the body. Even Keys himself admits that. We also know that large buoyant cholesterol is NOT related to heart disease, but that small dense LDL is. So it would be good to know what exactly raises our small dense LDL. Is it dietary fat?

In fact, it is not. It turns out that it is not saturated fat or cholesterol in the diet that raises our small, dense, bad LDL. It is carbohydrate.

Let’s recap.
1. High levels of saturated fat and cholesterol in the diet do not lead to high levels of cholesterol in the blood.
2. High levels of cholesterol in the blood are not a good predictor of heart disease. It is a particular pattern of cholesterol in the blood (Pattern B) that is related to heart disease.
3. The dietary component that leads to Pattern B is not fat, it is carbohydrate.

Just to put this whole debate to bed, and to put the final nail in the coffin of the Diet-Heart Hypothesis, let’s look at one final study. In January of 2010, a landmark study from the Harvard School of Public Health and the Children’s Hospital Oakland Research Institute was published in the American Journal of Clinical Nutrition. They evaluated dietary data from 347,747 participants from eight countries across 21 different studies over 25 years. The study’s verdict was that “there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk for heart disease.” Dr. Ronald Krauss, the study’s principal investigator and director of atherosclerosis research at Children’s Hospital said, “It’s the wrong message that saturated fats are artery-clogging or evil.”

A Primer on Fats
Fats are a vital nutrient that are required by the body for energy and structural growth and repair. They are important for cellular function, for absorption of vitamins A, D, E, and K, and for maintenance of skin and hair. We can burn fat for fuel. In fact, fat is a better source of fuel than carbohydrate because it is slower burning and leads to steady energy, unlike carbohydrate, which results in an energy high followed by an energy crash.

There are many types of fats, including monounsaturated, polyunsaturated, saturated, and trans fats. Let’s take a look at each one and figure out how much of each we should be eating based on how each one affects our bodies.

Saturated Fats
Saturated fats are generally solid at room temperature and are found in meat, coconut, avocado, and butter. Saturated fat is vital for many proper bodily functions, including vitamin absorption, calcium uptake, immune function, and cell membrane structure. It is a rich source of fat soluble vitamins. Because it is less susceptible to oxidation than other fats, it is less likely to lead to heart and other diseases. Contrary to popular belief, saturated fat does not cause heart disease, diabetes, or cancer, nor does it make you fat.

According to Kurt Harris, MD., “SFA (saturated fatty acid) does not cause heart disease and does not make you fat. To the contrary, the hormonal satiety and lack of insulin response from eating fats is the key to weight optimization and avoiding the diseases of civilization caused by hyperinsulinemia and high blood glucose levels, diabetes, metabolic syndrome, and degenerative diseases like Alzheimer’s dementia and many of the commonest cancers.”

You should eat as much saturated fat as you like. It is a good source of vitamins and energy, keeps you full, and promotes steady blood sugar. Coconut oil is a particularly good cooking fat, because it is less vulnerable to oxidative damage from high-heat cooking than other fats.

Monounsaturated Fats
Monounsaturated fats are liquid at room temperature and are found in olive oil, flaxseed oil, canola oil, avocado, nuts, and meats. Notice that I wrote that “they are found in.” Conventional wisdom would have you believe that meat only contains saturated fat and olive oil and avocado contain only monounsaturated fat. In fact, check this out:

Olive Oil is 75% monounsaturated fat and 15% saturated fat
Avocado is 65% monounsaturated fat and 15% saturated fat
Steak is 45% monounsaturated fat and 35% saturated fat

Interesting, huh? Bet you didn’t think that when you were using “heart-healthy” olive oil that you were consuming quite a bit of saturated fat, or that when you were eating steak, so vilified by the press and the American Heart Association for its saturated fat content, that you were actually consuming MORE monounsaturated fat than saturated fat.

In general, you can eat as much monounsaturated fat as you like, but be aware that foods that are high in monounsaturated fat also contain polyunsaturated fats (that is what makes up the remaining proportion of fat in the chart above, for those of you who added up the monounsaturated and saturated fat content and realized it didn’t equal 100%). Polyunsaturated fats are the ones we need to be concerned about for having detrimental health effects.

Polyunsaturated Fats
Polyunsaturated fats are liquid even when refrigerated and go rancid easily, especially when heated. They are found in grains and a number of industrial oils, including soybean, peanut, vegetable, corn, cottonseed, sunflower, and safflower oils. Fish and nuts are also high in polyunsaturated fats.

Heating them can cause oxidation, which results in free radical damage, which can cause cell membrane damage, wrinkles, and arterial plaque build-up. Polyunsaturated fats have only been prevalent in the human diet in large quantities since the Industrial Revolution, an incredibly short period of time in human history, because the technology to extract them did not exist before about 1800.

There are two types of polyunsaturated fats: Omega-6 and omega-3. Anthropological and modern research suggests that our total polyunsaturated fat intake should be no more than 4% of our daily calories, and that the ratio of omega-6 to omega-3 fats should be approximately 1:1.

Today’s Standard American Diet generally has an omega-6 to omega-3 ratio of anywhere from 20:1 to 30:1. Ratios so out of sync with our genetic makeup promote systemic inflammation, obesity, diabetes, heart disease, cancer, autoimmune disease, metabolic syndrome, high blood pressure, blood clots, and suboptimal brain development and depress neurological and immune function.

Better omega-6 to omega-3 ratios are shown to be related to increased bone density and decreased risk of diabetes, arrhythmias, heart disease, arthritis, asthma, and death due to heart disease.

Although some nutritionists will claim that a ratio of 4:1 is acceptable, many others believe it is important to get to a ratio of 2:1 or 1:1 every day. Trying to reach that ratio at each meal is unnecessarily complicated, and trying to reach it weekly is not enough.

In order to achieve a ratio of 2:1 or 1:1, you will need to completely avoid processed foods, fast foods, soybean oil, corn oil, sunflower oil, safflower oil, cottonseed oil, and peanut oil. Purchase grass-fed beef and pastured chicken, eggs and butter as opposed to conventionally raised beef and poultry products. Grass-fed beef has an omega-6:omega-3 ratio of about 5:1 compared to 9:1 for conventional beef. Pastured eggs have a ratio of about 1.5:1 compared to 20:1 for conventional eggs.

If you cannot afford or do not have access to grass-fed beef and pastured poultry products, you can choose low fat meat and consider supplementation with fish oil. One to 3 grams of fish oil a day should suffice. Be sure to talk with your doctor prior to starting any fish oil supplementation, especially if you are taking a blood thinner or aspirin therapy.

Two to four servings of fatty fish (salmon, herring, sardines, mackerel) per week, or two servings of fish plus omega-3 rich oils (walnut and flaxseed oils) per week will help balance your omega-6:omega-3 ratio.

In sum, limit polyunsaturated fat intake to no more than 4% of daily calories. But some is actually necessary for bodily functions (as it cannot be made by the body, thus the term “essential fatty acid”). Aim for a ratio of 1:1 omega-6:omega-3.

Trans Fats
Trans fats are unnatural, hydrogenated, chemically altered fats that are shelf stable. The body does not recognize trans fats and so does not eliminate them from the body. This allows trans fats to be absorbed through cell membranes and ruin cell metabolism. Trans fats are related to inflammation, atherosclerosis, diabetes, obesity, and immune system dysfunction. Trans fats also cause a redistribution of fat tissues into the abdomen (the apple shaped body). Fat tissue around the internal organs in the abdomen is related to heart disease. No one should ever consume unnatural trans fats. (It is true, however, that small amounts of trans fats occur in nature, and these do not need to concern us.)

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Harris, Kurt G. (2009). Fats and Oils. Archevore. Retrieved August 25, 2011.

Kendrick, Malcolm. (2002). Why the Cholesterol-Heart Disease Theory Is Wrong. Retrieved August 25, 2011.

Keys, A., Anderson, T., Mickelson, O., Adelson, S. F., and Fidanza, R. (1956). Diet and Serum Cholesterol in Man: Lack of Effect of Dietary Cholesterol.” Journal of Nutrition. May 10; 59(1):39-56.

Kresser, Chris. (January 20, 2010) The Most Important Thing You Probably Don’t Know About Cholesterol. Retrieved August 25, 2011.…

Kresser, Chris. (February 3, 2011) 9 Steps to Perfect Health- Nourish Your Body. Retrieved August 25, 2011.

Self Nutrition Data. Retrieved August 25, 2011.

Siri-Tarino, P. W., Sun, Q, Hu, F. B., Krauss, R. M. (2010). Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. American Journal of Clinical Nutrition. 2010 ajcn.27725; First published online January 13, 2010. doi:10.3945/ajcn.2009.27725.

Sisson, M. (2008). The Definitive Guide to Fats. Mark’s Daily Apple. Retrieved August 25, 2011.

Sisson, M. (2008). More on Omega. Mark’s Daily Apple. Retrieved August 25, 2011.

Taubes, G. (2001). Good calories, bad calories. New York: Anchor Books.

Taubes, G. (2002). What if it’s all been a big fat lie? The New York Times, July 7, 2002.

Wellness Mama. (2010). Guide to Fat. Wellness Mama. Retrieved August 25, 2011.

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