Eat Fat, Get Thin_Why the Fat We Eat Is the Key to Sustained Weight Loss and Vibrant Health
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AA—arachidonic acid (omega-6 fatty acid that can be derived from LA and is good for membrane flexibility and permeability): found in animal foods like fish, poultry, eggs, and meat.
GLA—gamma linolenic acid (omega-6 fatty acid derived from LA): found in evening primrose, borage, or hemp oil.
Omega-6 Fats
Omega-6 fats typically get a bad rap, as they tend to cause inflammation in the body. But not all are harmful. Omega-3 fats are anti-inflammatory. The problem arises when the balance is tipped in favor of too many omega-6s compared to omega-3s.
We evolved to have a good ratio of omega-6 to omega-3 fatty acids of about 1:1 to 4:1. But our modern diet now provides far too many omega-6s (found in processed food, corn and safflower oils, and conventionally raised meat) and not enough omega-3s (found in wild-caught fatty fish, fish oil, and grass-fed meats).
When there are too many omega-6s and not enough omega-3s in the cell, things can start to go terribly wrong. An imbalance has been shown to depress immune system function, contribute to weight gain, and cause inflammation.15 Dr. Artemis Simopoulos, one of the world’s leading researchers on omega-3 fats, explains that “excessive amounts of omega-6 polyunsaturated fatty acids (PUFA) and a very high omega-6/omega-3 ratio, as is found in today’s Western diets, promote the pathogenesis of many diseases, including cardiovascular disease, cancer, and inflammatory and autoimmune diseases, whereas increased levels of omega-3 PUFA (a low omega-6/omega-3 ratio) exert suppressive effects.”16
In an article published in Biomedicine and Pharmacotherapy, Dr. Simopoulos reviews in detail the risks of going against our evolutionary balance of omega-3 and omega-6 fats.17 The increased intake of omega-6 fats oxidizes your LDL (bad cholesterol), making it rancid and more likely to cause heart disease. It also makes your blood more sticky and likely to clot and blocks the uptake of the good omega-3 fats into your cell membranes. All bad news for your health.
Remember, food is information that influences the expression of your genes, and this is certainly true when it comes to foods containing omega-3 and omega-6 fatty acids. Omega-3 fats reduce the expression of inflammatory genes and molecules in the body, while omega-6 fats promote the expression of inflammatory genes. Omega-6 fats are heavily present in refined vegetable oils, like corn, safflower, and soybean oil. Although these oils have been considered the “healthy” alternative to saturated fats in the past, we now know the health dangers that come from refined oils (see Chapter 6 for more). They should not be part of your diet.
Unrefined oils are a better choice; however, the ratio of omega-6 to omega-3 fats is still important. The polyunsaturated unrefined oils that have the best ratio are flaxseed oil, walnut oil, and hemp seed oil, but make sure you don’t heat them.18 Unrefined oils are cold-pressed or expeller-pressed; neither of these processes uses the chemicals or solvents that are used in the oil-refining process.
Let’s look at the omega-6 fats in more detail.
Medium-Chain Omega-6s: Linoleic Acid (LA)
Linoleic acid is now the most abundant fat in our diets and is highly concentrated in most vegetable and seed oils, especially soybean, safflower, sunflower, corn, and cottonseed oils. It has been consumed in unprecedented quantities over the last 100 years. Soybean oil consumption has increased 1,000-fold since 1900. Since soybean oil lowers the bad cholesterol, or LDL, most doctors love it and recommend that we swap it out for saturated fats. But the story is not so simple. Too many omega-6 fats from soybean and other vegetable or seed oils compete with omega-3s in your body and interfere with the heart-protective benefits of omega-3s. Even worse, these oils can be easily damaged by oxygen and become oxidized; in the body they can turn LDL rancid and dangerous.19 These oxidized fats are called OXLAMs, or oxidized linoleic acid metabolites. Using these oils for frying, especially for frying carbs (like French fries), makes them even more harmful.
Linoleic acid, mostly from soybean oil, accounts for about 90 percent of all PUFA intake or about 7 percent of total energy intake. That’s a lot of unstable oil in our diet. Pre-agricultural humans who lived in Africa consumed only about 3 percent of calories as LA from wild meat. Other ancestral humans living in coastal areas would have consumed less than 1 percent. There is no historical precedent for consuming our current amount of LA, and it has been called a “massive uncontrolled human experiment.”20
Populations with traditionally low intakes of LA have a very low risk of heart disease. There are conflicting studies, but when separated out from diets that also include omega-3 fats, LA alone seems to increase the risk. The one large randomized controlled study that reduced LA to pre-industrial levels found a 70 percent reduction in heart disease and death.21 LA should not be a significant portion of your diet, despite common recommendations to replace saturated fats with omega-6 linoleic acid from vegetable oils. See more on omega-6 fats in Chapter 6.
Long-Chain Omega-6s: Arachidonic Acid (AA)
Arachidonic acid is found in eggs, beef, poultry, pork, liver, tropical fish, and farm-raised fish. It is a major component of all your cell membranes, including those in your blood vessels, platelets, and immune cells. It can be converted in the body into all sorts of metabolites, called prostaglandins and leukotrienes, some of which promote inflammation and clotting. These metabolites are needed to maintain a balance with the anti-inflammatory omega-3 fats. It is not as if omega-6 fats are only bad, or omega-3 fats are only good. It is all about balance. Wild and pasture-raised animals have a good balance of AA and omega-3s, whereas industrial animal production has led to more AA and almost no omega-3s. Some amount of AA is necessary, but too much is harmful.
GLA: A Long-Chain Omega-6
One beneficial source of omega-6 fats is gamma linolenic acid (GLA). GLA is a plant-derived omega-6 most abundant in the seeds of a Mediterranean flower known as borage or evening primrose. Although a member of the omega-6 family, it’s metabolized differently from other omega-6 fats. New research reveals this nutrient’s power to combat chronic inflammation, eczema, dermatitis, asthma, rheumatoid arthritis, atherosclerosis, diabetes, obesity—even cancer.22 GLA is rarely in our diet. Most people are deficient in it and would benefit from taking borage or evening primrose oil supplements. You need just a little GLA to reap the benefit.
Omega-3 Fats
Considering that the body needs fewer omega-6 fats than are present in the standard American diet, and desperately needs more omega-3 fats, focusing on consistent intake of omega-3 fats is vital for good health. The best dietary sources of omega-3 fats are wild-caught cold-water fatty fish and seafood, high-quality fish oils, and grass-fed meat and dairy.
The benefits of omega-3 fats have been well studied and documented. Here is a list of conditions that these beneficial fats help:23
High cholesterol
High blood pressure
Heart disease
Diabetes
Rheumatoid arthritis
Osteoporosis
Depression
Bipolar disorder
Schizophrenia
ADHD
Cognitive decline
Skin disorders such as eczema and psoriasis
Inflammatory bowel disease
Asthma
Macular degeneration
Menstrual pain
Colon cancer
Breast cancer
Prostate cancer
Diets high in good fat support your brain function. The brain is made primarily of phospholipids, the simplest form of fats. Omega-3 essential fatty acids provide proper fluidity for your brain cell membranes.
A study on the role of omega-3 fatty acids in depression showed that they were more effective than placebo for depression in both adults and children in small controlled studies and in an open study of bipolar depression.24 A study done by Dr. S. Jazayeri published in the Australian and New Zealand Journal of Psychiatry comparing the therapeutic effects of EPA and fluoxetine (Prozac) in major depressive disorder showed that EPA is as effective as Prozac in treating maj
or depressive disorder.25 That’s right: omega-3 fatty acids can alleviate the symptoms of depression as well as one of the most widely prescribed drugs in America today!
Here’s a little more detail on each of the omega-3 fats:
Medium-Chain Omega-3s: Alpha Linolenic Acid (ALA)
Alpha linolenic acid is the main plant source of omega-3 fats. It is found in soybean oil, flaxseeds, hemp and chia seeds, walnuts, and canola oil, as well as a little in green leafy vegetables. Soybean-oil-based salad dressings and mayonnaise are the biggest source of ALA but are also accompanied by large amounts of omega-6 linoleic acid (LA), so I recommend avoiding soybean oil. Omega-3 fats from ALA are protective for health, and small amounts (5 to 10 percent) can be converted to the more beneficial long-chain omega-3s (EPA and DHA). However, in diets with lots of LA, the ALA cannot be converted to EPA and DHA. In one large study, ALA was associated with a 73 percent reduction in heart attacks and death, but only when the LA was reduced at the same time.26
Long-Chain Omega-3s: EPA and DHA
These essential fats were a critical part of our evolutionary diet and now more than 90 percent of Americans are deficient in them. They typically come from wild animal foods, although chickens fed foods containing omega-3 fat produce eggs with omega-3 fats. They are found in cold-water fatty fish, including sardines, mackerel, herring, trout, salmon, anchovies, oysters, and tuna (though tuna is best avoided because of high mercury content). There are also more in wild game such as deer, elk, and antelope. Lower amounts are found in grass- or pasture-fed cattle and shrimp, mussels, squid, and scallops. DHA is also found in algae, the only plant form of the long-chain omega-3 fats.
As discussed, these amazing fats have many beneficial effects. Most Americans are deficient in omega-3 fats, and up to 25 percent of Americans consume almost no long-chain (EPA/DHA) omega-3 fats. Most ancestors who lived inland consumed about 660 milligrams a day of EPA and DHA, about six times the amount the average American gets. Those who lived in coastal regions consumed much more. Populations with high intakes of EPA and DHA have low risks of heart disease, diabetes, and obesity. The benefits increase with intakes of up to twenty times that of the average American.
TRANS FATS (TFA)
In the wide world of fats, as you can see, very little is black and white. There’s one exception, however, and that’s trans fats. There is no room for debate on this one: Aside from one particular type, trans fats are evil, nasty stuff.
Also known as hydrogenated fats, trans fats are mostly man-made and found in processed foods, shortenings and margarines, fried foods, and commercially produced baked goods.
No one any longer doubts the dangers of trans fats, and in 2013 they were finally ruled as “not safe to eat” by the FDA. On January 1, 2006, the FDA required that any trans fat content had to be clearly declared on all foods. This declaration was an achievement, especially for the Harvard School of Public Health, which had been advocating since the early 1990s for transparency of trans fats in foods and supplements.27 However, buyer beware! A product labeled “trans fat free” can still contain up to 0.5 gram of trans fat content. For example, Cool Whip, whose label says it contains zero trans fats, is made almost entirely from trans fats, but since it’s mostly air, it has less than 0.5 gram per serving.28 As of 2013 the FDA has begun the process to declare trans fats as no longer on the list of foods “generally recognized as safe,”29 after a lawsuit was filed by Dr. Fred Kummerow, the ninety-nine-year-old researcher who first highlighted the dangers of trans fats in 1957. All these actions are good news and steps in the right direction, but unfortunately, trans fats won’t be fully out of the food supply for a long time because there is a slow phase-in of the ban. Food companies have three years to remove them from their products, or they have to petition the FDA to permit them to use them. And there is no guarantee they will be replaced with better fats or compounds.
There is one type of trans fat that is fine to eat, though, and is even healthy. Dairy and beef contain CLA (conjugated linoleic acid), a different, naturally occurring trans fat that has beneficial effects on health and metabolism.
I Spy Trans Fats
It is important to be aware of the places trans fats may still be lurking: baked goods (crackers, cookies, cakes), snack foods (chips, microwave popcorn), frozen meals (pizza, TV dinners), Crisco, Pam spray, fake butter spreads, margarine, coffee creamer, pre-made frostings, and of course fast food.30 Keep trans fats out of your body by avoiding processed and packaged foods, avoiding fast food, asking for your food to be cooked in butter or healthy oils like coconut or olive oil at restaurants, and checking ingredient labels for the words “partially hydrogenated oil.” The good news is that many food producers are eliminating hydrogenated fats from their foods in an effort to keep business alive.
Historically we consumed about zero trans fat, and now in some populations in Western countries trans fat comprises up to more than 5 percent of calories. It was created around 1890 by scientists who developed the process of hydrogenation. It was cheap and thought to be healthier than butter, but it is far worse. It should never be consumed by humans or other living things. Even flies know better. They won’t land on a tub of shortening!
According to the FDA, “Trans fat is created when hydrogen is added to vegetable oil (a process called hydrogenation) to make it more solid.”31 Making certain oils solid was helpful for both storage and transportation. In the early 1900s there was an abundance of soy and a shortage of butter. The creation of margarine from soybean oil solved this problem. “Hydrogenated fat such as Crisco and Spry, sold in England, began to replace lard in the baking of bread, pies, cookies, and cakes in 1920.”32 Food producers had found a fat that was inexpensive to produce and had a long shelf life.
By the 1960s, trans fat products were being used in industrialized food and were replacing animal fats (butter and lard) both in the United States and abroad. And since trans fats were considered unsaturated fats, “health” advocates promoted the idea that margarine was better for you than butter.
However, there were suggestions in the scientific literature as early as 1981 that trans fats could be linked to coronary artery disease. According to the Harvard School of Public Health, a study done in Scotland that year speculated on the fact that there was a correlation between trans fats and cardiovascular disease. Another study by Harvard in 1993 strongly linked partially hydrogenated oils and heart attack risk. This study calculated that if you simply replaced 2 percent of trans fats in the diet with healthy fats, you could cut the risk of heart disease by a third!33
In 1994, it was estimated that trans fats caused 30,000 deaths annually in the United States from heart disease.34 Even so, the consumption of hydrogenated fats has increased significantly over the past half century. It has only recently started to decline.
The danger of trans fats comes down to this: They cause increases in small, dense, dangerous LDL particles, and they reduce HDL (good cholesterol). This in turn causes inflammation, heart disease, diabetes, dementia, and sudden death. It also increases the risk of cancer.
Here’s another unwanted gift from trans fats: obesity. There is a strong correlation between trans fats and weight issues. A study from Wake Forest Baptist Medical Center showed that diets high in trans fat increase belly fat and weight gain even without an increase in total calories. This study also further supported the link between trans fats and heart disease and diabetes.35 Harvard studies over the last three decades, too, have proved that eating trans fats promotes obesity and insulin resistance, which leads to pre-diabetes and type 2 diabetes.36
The dark tale of trans fats doesn’t end there. The link between cancer and trans fats is also of serious concern. A study on trans fatty acids and colon cancer showed that postmenopausal women who had high levels of trans fat in their diet doubled their risk of getting colon cancer.37 A study published in the American Journal of Epidemiology found that eating trans fats leads to precancerous polyps.38 Yet another study published in
the same journal found that a woman’s risk of breast cancer doubled if she had high levels of trans fats in her blood.39
So there you have it: the universe of fats in all its complexity. With your new knowledge in hand, you’re now empowered to make healthier choices about which fats to eat and which to avoid. In the next few chapters, I’ll give you even more insight and guidelines to help you answer, once and for all, the question, “What should I eat to stay healthy, prevent disease, and lose weight?”
5
The Surprising Truth About Fat and Heart Disease
For a long time, fat has been cast as the villain in the heart disease saga. The original assumption—that fat in general is bad for the heart—has since been replaced with the idea that saturated fat is bad and polyunsaturated and monounsaturated fats are good. The one thing we all agree on is that trans fats are evil, and monounsaturated fats (like olive oil) get to keep their top billing as good guys. But new evidence suggests that not all polyunsaturated fats (such as vegetable oils) are the heroes they originally appeared to be… and that saturated fat deserves some vindication.
WHAT DOES THE RESEARCH SAY?
Researchers from around the world, in both experimental and population studies, and in large reviews of all the research on this topic, consistently come up with the same conclusion. In 2015 leading fat researchers Patty Siri-Tarino, Ronald Krauss, and others reviewed all the latest data in an article titled “Saturated Fats versus Polyunsaturated Fats versus Carbohydrates for Cardiovascular Disease Prevention and Treatment.”1 They addressed all the controversies about saturated fat and polyunsaturated fats and carbs and found no link between total dietary fat or saturated fat and heart disease. This was in the context of the typical unhealthy diet consumed by most Americans. There is some data that swapping out polyunsaturated fats for saturated fats may be beneficial, but the studies are contradictory.