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Is Eating Fat Bad For You?

by Stevie Duncan | Nov 23, 2020 | Uncategorized

Why Eating Good Fat Won’t Make You Fat or Clog Your Arteries… But Eating Carbs Will!

A Historical Perspective on the “Low Fat” Diet

We have all been told that fat is bad for you. That it will clog your arteries and hurt your heart. This is not true! It is a myth that all fats are bad. For tens of thousands of years our ancestors, in a hunter-gatherer society, ate much higher proportions of fat in their diet than we do today. And their prevalence of heart disease and obesity was very, very low. It has only been since only the 1960s that we have sought to reduce the amount of fat in our diet. It is not a coincidence that since that time our rates of obesity, diabetes, heart disease, stroke and other complications of high blood glucose have exploded. For the last 60 years the federal government and the profit seeking food industry have successfully sold the American public on the concept of the “low-fat diet”. It is only in the last few years, with the acceptance of the low carbohydrate high fat diet, that the importance of increasing the amount of fat in our diet (and reducing carbohydrate intake) has been recognized.

What Causes Clogged Arteries?

Fat isn’t what clogs your arteries. In fact, sugar (simple carbohydrates) and starches (complex carbohydrates converted to sugar at the time of digestion) are actually the culprits. The more time your blood glucose spends above about 140 mg/dl, the more likely you are to have changes in your arteries leading to the diseases mentioned above. So really, it is more important to limit your sugar and complex carbohydrate intake and control blood sugar levels than it is to go “low fat”. (Note that the terms blood sugar and blood glucose are used interchangeably in this article.) The added benefit to your health of a combined low carb high fat diet is weight loss.

It is a little counterintuitive that eating fat does not make you fat and does not clog your arteries. Without getting too technical, here’s the explanation. When you eat sugar and complex carbohydrates, your blood sugar rises and the hormone insulin is released by your pancreas. Insulin is a “proinflammatory” hormone that contributes to the process of “atherogenesis” in your arteries. This means that high blood sugar and insulin combine to create inflammation in the walls of arteries which results in the formation of plaques on the inner lining of the arteries. In other words, high blood glucose and insulin cause inflammation in your arteries leading to plaque buildup, which can starve the supply of blood and oxygen to critical organs. The formation of these plaques in blood vessels results in a condition called atherosclerosis or, more simply, “hardening of the arteries”. Atherosclerosis eventually results in heart disease, heart attacks, strokes, changes in the small vessels in the brain leading to dementia, peripheral vascular disease and other diseases of clogged arteries. (By the way, this is why 80% of patients with dementia are diabetic or prediabetic. The connection between high blood glucose and dementia will be the topic of an upcoming blog and video.) By keeping your blood glucose in a normal or low-normal range, you can keep your insulin level lower as well. Consequently, by limiting your amount of sugar and starch intake, you prevent the clogging of your arteries. Lower blood sugars also lead to weight loss.

The low carb high fat diet does not lead to weight loss primarily by eating less food (calorie restriction). Large amounts of carbohydrate intake, along with the insulin that is released when you eat carbs, helps your body store fat. This is because the extra glucose in your blood, with the help of insulin, is converted to fat stores by the body. This causes weight gain especially by the storage of fat in the midsection of the body and the liver, leading to increased Body Mass Index, increased Body Fat Percentage, and even obesity. (The fat stored in the liver can also cause liver problems and leads to what is known as fatty liver disease or “FLD”.)

How Do I Add a Healthy Amount of Fat to My Diet?

A low carb diet with a high percentage of fat intake is safe. It is safe for your arteries, your heart and your brain . . . as long as a little attention is paid to the types of fat you ingest. The typical American diet now consists of more than 50% carbohydrates, and about 35 to 40% fat. (The other 10% to 15% is protein.) By dropping carb intake to 20% or so, and increasing fat intake to 65% or 70% our bodies release less insulin, and burn stored fat as fuel. This results in lower blood sugars, less artery disease, and weight loss.

Additionally, eating fat causes “satiety” which is that feeling in both your abdomen and in your brain that you feel full. Fat slows gastric emptying which keeps the food you just ate in your stomach for longer periods of time. So, when you eat fat, you eat less food overall. Carbs are not good at curbing your appetite. They do not help you achieve satiety readily. The food scientists working for food processing companies know this and have sought to develop and sell us high carb foods which keep us eating, and eating, and eating. We never feel quite full on breads, chips, crackers, ice cream, candy, pastries and the like. This is not an accident. The food companies want to sell us as much of their product as possible.

Which Fats Are the Good Fats?

So, what types of fat are best for us? To provide an overview, good types of fats include both some unsaturated fats and some saturated fats. Saturation or lack of saturation has to do with the types of chemical bonds between the molecules contained in the fat. This fact is not important to remember. However, it is important to realize that a single food often contains both types of fat. For example, grass fed beef contains both good unsaturated and good saturated fats.

Unsaturated fats can be either “polyunsaturated” or “monounsaturated” fats. Polyunsaturated fats are usually liquid at room temperature. These include the vegetable oils like corn oil, sunflower oil, canola oil and soybean oil. These polyunsaturated liquid oils are generally not good for you. These liquid fats (primarily vegetable oils) should be eliminated from your diet as much as possible. Be aware that vegetable fats make up most purchased salad dressings.

Solid foods containing healthy polyunsaturated fats include eggs, fish, shellfish and grass-fed beef and poultry. (Grass-fed meat is preferred, but can be expensive, so we do not consider this an absolute. Meats that are not grass-fed are OK if that is what is within the budget.)

Regarding monounsaturated fats, examples of foods containing good monounsaturated fats include nuts, olives and avocados. The best nuts are pecans, almonds, and walnuts. Olive oil is a monounsaturated fat which is the preferred liquid oil to use in cooking and food preparation. Again, it is the by far and away the most popular liquid fat that is healthy. This is why olive oil has gained notoriety as part of the Mediterranean Diet.

Saturated fats are mostly solid at room temperature, and in reasonable quantities are healthy to eat. This category includes coconut oil, dairy products (like cheeses, and butter; grass-fed if possible) fish, nuts, and again grass-fed meats. Butter is mostly a saturated fat, and preferable to margarine (see below). Whole milk also contains mostly saturated fat (so is the exception to the rule that most saturated fats are solid at room temperature). Be careful regarding milk, however, if you are counting carbs. . . as eight ounces of milk (skim or whole) contains about 13 grams of sugar.

Regarding cheeses, most cheeses are good sources of fat as part of a low carb diet. However, there is a short list of cheeses that should be avoided. These include highly processed cheeses like “spray cheeses” (Cheez Whiz), American Cheese (which is highly processed), ricotta and cottage cheese. Ricotta and cottage cheese should be avoided due to their relatively high carbohydrate content. Most other cheeses are acceptable as part of a healthy low carb high fat diet. These include goat cheese, blue cheese, cream cheese, parmesan, and cheddar, but also many others. And don’t forget “Cheese Crisps”. They are dehydrated (or fried) pieces of cheese. These are usually made of cheddar, gouda, or asiago. These serve as good alternative to the potato chips, pretzels, and tortilla chips which must be avoided on a low carb diet. (See our comments below on fried foods.)

Cured and deli meats are included in the saturated fat category as well. They are healthy to eat for most low carb dieters. Three potential issues arise with cured and deli meats. These are salt content, the fact they they contain nitrates and nitrites, and the issue of “fillers”. Except for these potential issues, which for most people are not an issue, they are as healthy as all other meats.

Regarding the salt in cured and deli meats, we do not feel restriction is needed related to these meats in healthy patients. Of course, if you have congestive heart failure, kidney disease or hypertension, salt intake may need to be restricted. (The issue of hypertension here is a little controversial with some physicians believing that weight loss with a low carb diet is a goal that supersedes strict restriction of salt in cases of mild to moderate hypertension.) Follow your doctor’s advice if these conditions apply to you.

We feel that the issue of nitrates and nitrates is not a significant issue as these potentially carcinogenic substances are already restricted to very low levels in foods by US government regulatory agencies like the FDA.

Finally, there is the issue of fillers. Fillers are also known as “cereal binders” and are used to add bulk to food and hold it together. In meats they are most commonly found in sausages, hot dogs, and fast-food hamburgers, but can also be found in other deli and processed meats. They are an issue because of the “hidden” carbohydrate content they can add to the diet. Be careful of these foods and check labels regarding carbohydrate content. Also, be careful of any relishes or ketchup eaten with these foods. They also can add significant carbohydrate dietary load.

So, for most low carb high fat dieters it is OK to go ahead and eat bacon, sausage, hot dogs, pastrami, peperoni, ham, turkey, salami and other cured and deli meats. You may also eat significant amounts of the “good cheeses” listed above. They are all part of a healthy low carb high fat dieting approach. In eating these foods, carbohydrate intake can be kept low, often without consideration of calorie restriction, or experiencing hunger. Many patients can eat nearly as much of these foods as they want and still lose weight . . . as long as carbohydrate intake is appropriately restricted.

Most saturated fats and the good unsaturated fats (listed above), in our opinion, should be considered healthy and can be eaten in reasonable quantities if carbohydrate intake is simultaneously restricted. This will result in weight loss, and will not result in artery disease. YES, that is correct. If carbs are limited, even red meat and cheese consumption, will not lead to heart disease and will lead to weight loss!!! By reasonable quantities we mean up to six portions per day, or about 165 grams of fat per day. This is enough to make up about 60% of a daily food intake.

What Types of Fat Should I Avoid?

Types of fat to be avoided include vegetable oils (mentioned above) and hydrogenated oils which are sometimes called trans-fats. (All trans-fats are hydrogenated; some other fats are also hydrogenated). Hydrogenation just means water molecules have been added to a fat, usually a vegetable oil, to make it more solid and stable, and to create a longer shelf life. Trans-fats and hydrogenated fats include shortenings (think Crisco) margarine and purchased mayonnaise, most fried foods and fast foods, many baked goods (think donuts, cookies) and many packaged foods. (Fast-food and packaged foods usually contain high levels of carbohydrates anyway, so their intake should be very limited on a low carb high fat diet anyway.)

Bending the Fat Rules a Bit to Help Lower Carb Intake: “Dirty Keto”

We do believe, for people initially making a big push to reduce carbohydrate intake, some of the “bad fat” foods are OK if eaten in limited quantities, as long as simultaneous reductions in carbohydrate intake are substantial. If carbohydrates are not reduced eating these “bad fats” is not a good idea. This is because the combination of a high carbohydrate diet and a diet with bad fats will lead to arterial disease and obesity.

Eating some of the “bad fats” as part of a high fat, low carbohydrate diet approach is referred to as a “dirty keto” diet. (The keto diet is a very stringent low carb diet. The Dirty Keto term is used even if the goal of the low carbohydrate diet is not so rigorous as to achieve ketosis.) The dirty keto approach includes the occasional fast-food hamburger with lettuce and tomato (no bun), some fried meats (i.e. fried chicken or chicken tenders that are not too heavily breaded), and even prepackaged fried foods like pork rinds and fried cheese crisps (More on the “Dirty Keto” diet in a future blog.) The bottom line is that we believe that eating healthy fats, and even eating some fats which are not healthy, is much, much better than consuming a high carbohydrate diet. This approach also helps make the low carbohydrate diet sustainable for longer periods of time, or even indefinitely. Many of our patients who have lost a lot of weight and maintained that weight loss for years have done so while consuming limited amounts of lower quality fats. We feel that in return for lowering carb intake substantially and avoiding elevated blood sugars and high levels of insulin release, a fat indiscretion is allowable occasionally. Additionally, this will still lead to weight loss, which results in overall improved health and wellness.


Only since the 1960s have Americans limited fat consumption . . . resulting in an explosion in diabetes and artery related diseases. The key to achieving healthy arteries and a healthy weight is lowering carbohydrate consumption. This means that an increase in fat consumption will need to occur. Fat can be consumed safely, increasing satiety and decreasing the overall number of calories consumed. “Good fats” include both saturated fats and some unsaturated fats, but it is important to know the best types of fat to eat. Vegetable oils, trans-fats, hydrogenated fats and fried foods should be mostly avoided. However, limited consumption of these fats (cheating a little bit with the “Dirty Keto” diet approach) is acceptable for individuals who are being successful at limiting their overall carbohydrate intake.

Call 937-800-4CGM for a free consultation to see if you are a good candidate to lose weight and keep it off with a CGM.

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