Well, this chapter is a hard one for me to write because I have spent most of my professional life decrying the consumption of fatty foods. There was a time that fatty foods seemed to be the source of all things evil.  If you ate fat you would become fat and you would die from fatty blood vessels or atherosclerosis.  It all seemed to make sense.  At the operating table when I cleaned out an abdominal aortic aneurysm in preparation for sewing in a Dacron graft to repair the aneurysm, the material we took out of the aneurysm wall looked like plain thick grease or lard.  It was gross.  I hate to say this but we used a sterile tablespoon to clear this material from the aortic wall.  So obviously when you saw greasy fat on a steak, it didn’t take much imagination to see the connection.  Eat fatty foods, and you will get fatty arteries and gain weight, complete with “love handles” and a fat belly.  There was a time when I even recommended that my patients avoid vegetable fats like oils and encouraged them to go easy on nuts.  The reasoning at that time was that if you wanted to avoid being overweight you just decreased the amount of fat that you ate.  Fat has 9 calories per gram.  Proteins and carbohydrates have only 4 calories per gram.  It was so logical.  You eat less fat and you will lose weight because you are eating fewer calories.

 Back in the 1960s we knew very little about the biology of fat metabolism and what the body does when we eat fatty foods.  I observed that people who were vegetarians seemed healthier than those who ate animal products and more fat.  It is true that I had to ignore some startling exceptions to this personal observation such as the African Maasai warriors who ate only meat and blood from their herds of cattle.  They thought that eating vegetables would lessen their manhood and bravery.  They did not become fat and they did not die from coronary artery disease.  Of course they also walked 10-20 miles per day in their herding, warring, and hunting activities.  I also had to ignore the emerging data from the countries around the Mediterranean Sea where people who ate very high fat diets with olive oil, nuts, avocados, fish, and some meats, still had low incidences of obesity and coronary artery disease. 

As some of the researchers of the day were attempting to research these topics, they became caught up in the politics of medicine.  If you wanted to do research on obesity, atherosclerosis, or hardening of the arteries, you had better ask for money to study the low fat diets.  No other diet was seen to be politically correct in justifying the research.  A few serious scientists protested and to the best of their funding ability began to study what our bodies actually do with fat when it is eaten.  This trend has broadened in the last few decades.  Some of the early investigators received a “lot of arrows in their backs”, but once Harvard and UCLA started looking into what is the biology of fat metabolism, our understanding began to change.

So here is the most up to date information that I can give you.  We know that our bodies need a certain amount of body fat.  It insulates and gives appealing curves and even supports some of our internal organs such as our kidneys which have no fibrous attachments other than the surrounding fat.  Very thin young women cannot ovulate and have children until they have achieved sufficient body fat to carry a pregnancy.

 Now what about eating foods that contain fat?  Well, fat is very satisfying and helps us to decrease the calories that we eat.  A number of the fats are essential for life.  We can make some of them ourselves and others have to be eaten.  More about this later.  But for right now let’s see body fat as a way to store calories that we may need for energy in the future. 

As you have already learned, our ancestors relied on these “energy sacks” to get through the long winters and times of tragedy or famine.  Genetically, individuals that were better at storing energy were more likely to survive and bear children who had the same biology.  Storing fat which could be later used for energy was perhaps one of the most important systems of the body and therefore helped our ancestors adapt to severe climate and geographic changes. 

Our bodies can take calories from many sources, both plant and animal.  These foods will often have a mixture of carbohydrates, proteins, and fats.  The calories from all three sources can be converted into energy; carbohydrates quickly, proteins and fats a little more slowly. 

Calories are used up in the digestion process, with more calories being used to convert protein and fats into energy than with carbohydrates.  The more calories we use to process food, the fewer calories we will store. Think about this.  You can now see that eating too many carbohydrates and not enough fats and proteins can backfire and lead to excess body fat. This is especially important if we are in a convenience laden environment and are not burning off those excess carbohydrates. 

Perhaps an illustration of our bank savings accounts can help clarify how this works.  We can think of the carbohydrates that we eat as using our “debit cards”. Money is immediately available for energy purchases.  The proteins and fats are converted to energy as well but it just takes a little longer.  This is similar to using your credit card that pulls money from your savings account later in the month.

When we have no immediate energy needs or we take in more than is needed right then, the body puts this energy into storage like a credit card/savings account. Now, picture two types of accounts.  The first one is utilized at night when we are sleeping and not taking in any food energy. The body must pull from this account by breaking down glycogen, a complex sugar molecule which has been stored in the liver.  The second savings  account is more long term.  This would be our fat cells.  As I said, fat storage takes a little more energy to pull off and it takes more energy to break the fat cell back into sugar for fueling muscle activity and internal body organs function.

 So now that you have this background information on what makes fat, let’s go back to the issue of eating fat in our diet.  We know that foods that have more fat in them do have more calories per unit of food but that same fat may assist us in staying trimmer.  How does this work?  Our bodies were established to “burn” or metabolize fat.  We are actually fat burning machines.  Some have said that the average weight person has enough stored fat to provide enough energy to jog for 200 hours.  And guess what, this energy is released in a steady, reliable manner.  By contrast if this same energy came from refined carbohydrates or sugar, it would be a chaotic up and down experience with an immediate rush of energy and then a sharp decline with cravings for more simple sugars.  Your daily life may look and feel like this last illustration.  So you can see why healthy fats may help us trim down. 

Dietary fats come in many forms.  You may have heard a lot about omega-3 essential fatty acids but perhaps you have not heard so much about the omega-6 fatty acids.  Both of these fatty acids are essential, meaning that we cannot make them internally and have to get them from our foods.  One hundred years ago, before the industrial revolution and machines started “making foods” by altering the structure and chemistry of normal grains, nuts, and oils, humans had a healthy balance of omega-6 fatty acids and omega-3 fatty acids.  The ratio was about 1:1.  Today, this ratio may be as high as 20:1 for most individuals who eat the typical Western Diet. 

Where are we getting all of these omega-6 containing foods? The answer is the polyunsaturated manufactured oils that appear in many of the highly processed packaged foods.  This high ratio of omega 6: omega 3 is at the root of many of our chronic degenerative diseases, many cancers, cardiovascular disease, arthritis, and other inflammatory conditions.  Studies have shown that improving the ratio to even 4:1 reduced cardiovascular mortality by 70%.  Ratios of 3:1 or 5:1 improved symptoms of asthma and arthritis respectively.  The out of balance harmful omega-6 fatty acids come from safflower, soybean, corn, peanut, and cotton seed oils.  Look at the ingredient list on any packaged processed food and you will be sure to find these offenders.  The food industry that provides us with cheese, eggs, milk, and meat contributes to this harmful balance of fatty acids.  They do this by feeding these omega-6 fats to the animals that provide us food. This is why it is important to choose animal foods that are raised naturally or free-range.  Beef that is grain fed will have the 20:1 ratio compared to beef raised on grass which will have a ratio of 3:1. 

Before we leave the oil fats, let’s not forget the omega-9 fatty acids.  They are not essential, because we can make them from other forms of fat.  Dietary use of olive, avocado, canola oil and many of the tree nuts have proven to be anti-inflammatory.  These fatty acids can improve the lipids or fats in our body.  They help us burn fat and protect us from inflammation related diseases, even some cancers.  This form of fat is often called monounsaturated fat and is prominent in the Mediterranean diet. 

Let’s now consider the subject of cholesterol.  I know that this will surprise you but cholesterol is not a fat.  It is a chemical structure called a sterol.  Since our blood is largely a water based fluid, this sterol must be transported for its necessary work in our body by a fat and protein transporter called a lipoprotein.  The science of these lipoprotein molecules and how they transport the sterol cholesterol is changing rapidly.

   Fifty years ago, we could only measure total cholesterol and we had no understanding of the sub fractions that you now known as the “good cholesterol”, high density lipoprotein (HDL) or the “bad cholesterol,” low density lipoprotein (LDL).  So we made early assumptions that eating fat raised cholesterol levels.  And sure enough, when people ate low fat diets the total cholesterol often did decline.  We learned later that this decrease in total cholesterol was largely due to a decrease in the HDL fraction or the “good cholesterol”.  

We then began to understand that the total cholesterol calculations included not only lipoproteins but also another “transporter” called triglycerides.  They are formed by three fatty acids and are bound together by a glycerol molecule.  This bond can be broken apart by the hormone-sensitive lipase (HSL) when energy is needed. 

Anything that blocks the breaking of this bond will lead to high triglyceride levels and is associated with diabetes and hardening of arteries.  You will learn in the Insulin Chapter (Chapter 8) that insulin can block this vital activity for energy production.  When people are overweight by eating too many refined carbohydrates, they will produce too much insulin resulting in an elevation of triglycerides that are so high their blood fractions have a milky appearance. 

Now let’s compare what happens when we eat a low refined carbohydrate diet.   The lipid fractions, HDL, LDL, and triglycerides change to bring us more health and to protect us from diseases such as cancer, hypertension, diabetes, and heart disease.  What really surprised me in one of these studies was the finding that even the saturated fatty acids in the blood of the research subject declined significantly when contrasted to subjects who were eating a low fat diet. 

We often think of saturated fatty acids as something bad for artery health but when used without refined and processed carbohydrates, these fats may be handled quite well by the body’s lipid metabolism mechanism.  The saturated fats are quickly converted to monounsaturated fats which we know promotes health. 

This area of diet is highly controversial.  It is my opinion that the large population studies about “high fat” diets causing cardiovascular disease may be confounded by what the “high fat diet” really is.  What do you think of when you think of “high fat”?  Well yes, you might think of bacon and steaks but what about French fries, hamburgers with refined wheat buns, and all those desert pastries.  It may be that the combination of “high fat” and “high refined carbohydrates” create the lethal mix that brings disease to us. 

A number of dietary intervention studies that have been randomized to low carbohydrate (<5%)  compared to low fat (<30%) have shown that the low carbohydrate interventions produced more heart favorable changes in insulin sensitivity and the lipoprotein fractions.

By contrast, if we take the two most opposite dietary systems of fat usage, the Atkins vs. the Ornish, we find that they both avoid refined foods and sugars that are linked to insulin resistance and obesity.  Perhaps this is why both dietary systems can report healthy changes in weight and the risk factors for chronic degenerative diseases such as cancer, heart disease, and diabetes.  They both avoid deadly refined carbohydrates and sugars. 

Recently, science has taken another step forward in the understanding of lipid metabolism and the risk of cardiovascular disease.  It is now possible to not only determine the sub fractions of the total cholesterol such as LDL or HDL, but we can identify the lipid particles’ “shape”.  Ideally, it is best if both fractions are “large and fluffy”.  My patients are now making their lipid particles larger and healthier by decreasing their use of refined and high glycemic load carbohydrates.  Randomized intervention studies are also documenting these same findings. 

Even though a few cultures live almost exclusively on fats, we will round out this section by talking about a balance of a diet of healthy fats, proteins, and a large array of high fiber carbohydrates that are low glycemic load.  This diet does not  over-stimulate the production of insulin.  Fiber is an unsung hero for weight loss.  Whole grains, legumes, and vegetables of all sorts are not only filled with vital nutrients but also with hunger satisfying fiber.  Feeling full signals the brain that enough is enough.  This is the same fiber that improves the healthy gut microbiome that you will learn more about in Chapter 11.  Our goal is to have 5-7 servings of low glycemic load organically grown fruits and vegetables every day along with our healthy choices of fats and proteins.  You can see examples of this type of diet at the end of the book. 

You can choose from a vegan to an omnivore lifestyle.  If your plan is working for you and maintaining you at a healthy weight, stay with it.  If on the other hand, you seem stuck with what you are currently doing, do not hesitate to try another plan. 

Three Types of Fat Monounsaturated Fatty Acids are found in olive oil, canola oil, avocados, and most nuts.  (Omega 9-the more the better) Polyunsaturated Fatty Acids are found in certain fishes such as salmon, sardines, and herring. They are also in such oils as corn, sunflower, safflower, flaxseed, soybean, grape seed, sesame and cottonseed. Saturated Fatty Acids are found in butter, lard, coconut oil, and palm oil. Essential Fats are those that our body does not produce on its own, so we need them from our diet. Omega-3 is in the leaves of green plants and algae, and in shellfish and cold-water fish. Omega-6 is found in grains and seeds, as well as the chickens and  cows that eat them. We get more of this type of fat than we need, which is why we need more fish in our diet and less grain.