A hundred dieters just turned their heads. "What? The SKIN? That's where all the FAT is!"
Well, let me regale you with a tale of ego, bias, and misdirected good intentions.* Back mid-twentieth century or so, public health officials and doctors were trying to figure out what caused heart disease. At the time, there was only a blood test available for total cholesterol, and investigations of atherosclerotic plaques showed that they were made of cholesterol! Also, excess fat on your body is saturated fat, pretty much. So these researchers decided 1+1 = 2, because people with high total cholesterol did seem to have more heart attacks.
Dr. Ancel Keys, made famous for his conscientious objectors study in WWII, inventing the K ration, and also for feeding institutionalized schizophrenics different diets and monitoring their cholesterol, came up with the Dietary Fats Hypothesis. Which is, basically, that eating a diet high in fat causes heart disease. For evidence, he produced his (also famous) Seven Countries Study, where countries where people ate low amounts of fat (such as Japan), had less heart disease than countries where people ate more fat (such as the U.S.). Unfortunately, he hand-picked these countries, leaving out the troublesome ones (such as places in Finland, Crete, Newfoundland, France, Switzerland, etc. etc. etc.(1)) where people ate plenty of fat, and had low incidence of heart disease. For various reasons, this dietary fat hypothesis took off, and before you know it, Time magazine had a cover with fried egg eyes and a bacon frown, and none of us were allowed to eat the skin on our chickens anymore. We were told to substitute "bad" animal fats with "good" vegetable fats (seed oils, like corn and soybean and safflower) and eat more carbohydrates in lieu of fats.
This recommendation was basically an unregulated experiment on the population of the United States, because there was never good evidence that this would prevent heart attacks or, perhaps more importantly to most of us, lessen overall mortality, though cholesterol will get lower if you lower your intake of saturated fat. Though really, if you look at the data, it doesn't matter.
The lone famous outlier was Dr. Atkins, who really did some brilliant work. Unfortunately, he was apparently something of a jerk, and people in the scientific community would go out of their way to prove him wrong and discredit him. Alas. (In my opinion, Atkins didn't get it completely right either, but he wasn't completely wrong).
Now let's fast forward to the 21st century, and look at all the scientific data we have accumulated over the years to show that dietary fat (especially saturated fat) causes heart disease and early death: Um, well, there isn't any (2). Well, okay, a few studies in people with advanced ischemic heart disease or diabetes showed worse outcomes with high amounts of saturated fat, but these studies weren't controlled for the kinds or amounts of carbohydrates the study subjects were eating, and in one of the studies the 'animal fats' involved included sausages and processed deli meats and the like (3). In fact, the Framingham Heart Study (perhaps the most famous heart disease study in history) has studied the dietary habits if three generations of people, and found no link between total dietary fat consumption and ischemic heart disease. Worse, though the Nurse's Health Study shows no correlation between total dietary fat consumption and heart disease in women (4), other epidemiological studies show a higher risk of cancer in women who consume low fat diets (5)(6).
Don't believe me? Check out this article in Scientific American about a meta-analysis of ALL the major dietary studies, comparing the daily food intake of some 350,000 people.
I'm not trying to promote a silly blood type or food combining diet, folks! I'm a mother and a doctor who wants to not worry about her weight and keep my kids from becoming the next diabetes statistic, so I have done a bit of homework.
All right, back to the main point. Yes, Fat (in general) = Not Bad (or, in some cases, V. Good!). Before you say, "Suweet! I'm off to Cinnabon!" please remember, fat+sugar = kiss your pancreas good-bye. And unfortunately, ladies and gentleman, all those fast "food" joints serve up their industrial meat with special sauces loaded with sugar on sugary buns with sugar sprinkles, more or less, so the KFC Double Down is still not a good idea. However, there is no consistent medical literature to back the AHA Recommended Diet limiting fat consumption to 30% of calories daily.
The whole fat story is more complicated, and I'm about to bring back the biochemistry, so if you are still interested, keep reading (at the very end will be a summary about what to eat), because, guess what, there are good fats and bad fats (7), but they just aren't the ones you might think:
1) The Good Fat: Monounsaturated fats, such as olive oil. Everyone pretty much agrees on this one. Olive oil is good for you. Hooray! In fact, the new healthy diet du jour is the Mediterranean Diet with its focus on healthy fats - olive oil! (Did you know that while the people in Crete had low incidence of heart disease, they have similar incidence of type II diabetes to the rest of Europe (8)? But I digress...) Another famous monounsaturated fat is canola (or rapeseed) oil. Unfortunately, canola oil is highly processed and some of it is even loaded with trans fats, which brings me to...
2) The Bad Fat: Trans Fats (boo!). What are trans fats? Well, unsaturated fats have chemical bonds that are, in nature, shaped like little boats. If you take an unsaturated fat and then heat it and use a chemical catalyst to make it hydrogenated (think margarine - boo!), then some of the chemical bonds are trans bonds, which are like little boats if they were cleaved by lightning and the stern flipped over and all the people on board were doomed to death by drowning. Trans fats are also unnaturally high in industrial grain-fed beef, according The Primal Blueprint. Trans fats are yet another example of the industrial process creating frankenfood that we just aren't able to metabolize correctly, and it killed us in droves. And be careful about those "0g trans fat" labels on food nowadays - up to 0.5g trans fat per serving can be rounded down to 0, so if you eat 5-6 servings of chips, you could be consuming up to 3 grams of deadly trans fats. Read the label and pass on ANY food with hydrogenated or partially hydrogenated oils in it. Do you know how to get an animal to develop atherosclerosis? Feed it something it doesn't normally eat, like red meat to rabbits.
3) The Fat that Will Make You Pull Your Hair Out: Polyunsaturated Fats (PUFAs). PUFAs are vegetable seed oils and fish and nut oils that we were told to eat in lieu of saturated animal fats. Ditch the butter, eat margarine! Ditch the lard - fry in vegetable oil! It turns out there are two kinds of PUFAs, omega 6 and omega 3. In general, most seed and nut oils are omega 6 (though macadamia nuts are pretty high in omega 3), and fish oil and flax oil are omega 3. Who cares? Well, the balance between omega 3 and 6 is important. In our modern diet LOADED with soy and corn oil (seriously, look on the ingredients of ANY processed food), we have a huge imbalance between omega 6 and omega 3. Omega 3 is only high in things like wild caught fish (NOT farm raised - those fish are fed corn/grain, and the actual omega 3 fats in salmon come from the little diatoms and algae they munch on in the wild) and grass-fed beef. So who cares if our ratio is off? Well, PUFAs (especially omega 6) are definitely linked to cancer (9). Yup. Different kinds of cancer. And fatty liver and insulin resistance. (sorry, chip lovers. sorry, infant formula drinkers, etc. etc. etc.). Oh, and corn-fed beef is also higher in omega 6 and almost missing omega 3, whereas grass-fed is reasonably more balanced between the two. Truth is, you don't want to ingest a high amount of PUFAs (though we need some to survive), but they are almost impossible to avoid. If you take some extra omega 3s, though, you can diminish the impact. Fat is important. Your brain is 60% fat - and it needs to be the right kind, or things don't work properly (more details on fats and the brain in another post).
4) The Fat of Kings: Saturated Fat. Poor saturated fat. That's animal fats and a few tropical oils (lard, beef tallow, eggs, butter, the skin on your chicken, etc. and palm and coconut oils) Did you know that the cell membranes of every cell in your body require saturated fat to work properly? Ingesting saturated fats will definitely raise your total cholesterol. It increases your LDL ("bad" cholesterol) - which I am going to go out on a limb a bit and say probably doesn't matter in the slightest, as long as you have a low number of "small, dense" LDL which are associated with high carbohydrate diets. Saturated fat also increases your HDL (hooray! "Good" cholesterol!), thus, total cholesterol will go up. You know who has been proven to do poorly with total cholesterol over 250? Men with known ischemic heart disease under the age of 50 (10). You know who hasn't been proven to do poorly with high cholesterol? Anyone else. In fact, in Japan they ask people to eat more of certain kinds of fats because it lowers risk of stroke. Did you know that a large percentage of the fat in a porterhouse steak is the same monounsaturated fat as in olive oil? Yeah, the Good Fat! Did you know that the only saturated fat to be linked to issues with ischemic heart disease and insulin resistance is palmitic acid, which is found only in small amounts in coconut oil, for example, which we have been told to avoid? Did you know that the young Masai warriors and the Tokelau eat diets of 33% and 50% or their total calories from saturated fat respectively, and have no appreciable atherosclerosis, diabetes or ischemic heart disease while they are eating their traditional diets?
(But why is everyone on lipitor? Ah, statins. They have been proven to help men with ischemic heart disease or people with hereditary hypercholesterolemia lower their risk of further heart disease. And they do lower cholesterol, which is likely not the reason they help. They are also thought to decrease inflammation, which is the real devil (along with small, dense LDL which are increased, again, in high sugar diets) - and statins can have a high cost.
This is a long one. Let's wrap it up: Telling everyone to cut the animal fat and exchange it for vegetables oils, high carbohydrates and saying sugar wasn't a major health problem was an unmitigated public health disaster leading to record obesity and failed diets for 30 years. I'm not going to pull any punches here, because doctors should know biochemistry, and a lot of this is basic, basic stuff.
You want to eat fat? Go olive oil, wild fish oil, and some nuts. Organic eggs have 5-7 times the DHA (an omega 3) of conventionally grown ones, and 1/5 of the omega 6 (11). Get a lovely steak derived from a cow that spent its life eating what it was supposed to eat - grass, not corn! Eat the skin on your chicken.
Bold? Not about to take a (in my opinion, hopelessly outdated) cholesterol test for a life insurance policy or disability policy, and unafraid to tell your doctor that you don't care about your total cholesterol or your LDL as much as whether you have a negligible percentage of small, dense LDL, your triglycerides are low and your HDL is high? Fry your eggs and organic ground turkey in coconut oil. Stir-fry with pastured butter. Yum Yum! Some individuals with certain genetic profiles may need to watch their saturated fats more closely than most of us. I'll go into this in more detail in a later post.
Don't go nuts and eat your fats with a lot of sugar or a huge pile of pasta, at least not very often.
*all meticulously documented in Good Calories, Bad Calories by Gary Taubes. He is the secondary source for much of my information. Dr. Stephan Guyenet has examined many of the primary sources on his blog, Whole Health Source