Fats
In a nut shell:
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Are packed with healthy calories.
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Are a major source of fuel storage.
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Are essential for cell function, cell signaling and brain health.
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Unsaturated and Omega-3 fats are the healthiest fats and should be in your daily meals.
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Saturated fats in moderation are beneficial.
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Trans (hydrogenated) fats are harmful and have no place in your diet.
For a long time dietary fat received a lot of bad press, hence the emergence of various fat free diet plans and products. But that was a great oversimplification. Fat is considered one of the three major macronutrients that should be part of our daily meals. And this makes great sense; among other things, fat is the building block of our cell membranes. Without it our cells cannot form a protective and functional cell wall, and without cells, we won’t have any organs.
Structure and function:
Other than carbohydrates, fats are the major currency for energy in our body. In fact humans store most of their energy as fat and very little as carbohydrates. Therefore, any prolonged activity depends on fat as its major source of energy. Without fat our heart won’t be able to pump or our muscles won’t have enough fuel for longer periods of exertion.
Fat is also essential for proper brain function as it plays a major role in both remodeling and signaling of the brain cells. So fat is good and important, and you should include it in your diet. But just like carbohydrates, fats come in various forms: some good and some not so good.
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Fats are categorized mainly based on their molecular structure; for dietary purposes these are:
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Unsaturated fats
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Omega 3 fats
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Saturated fats
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Trans (Hydrogenated) fats
Fats are made of a backbone called glycerol. Most dietary fats have the same glycerol backbone. Attached to the glycerol core are differing number and types of free fatty acids (ffa) which are made of long chains of carbon, hydrogen and oxygen. The composition and spacial arrangement of the ffa chains make fats into healthy and unhealthy forms.
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It is also worth mentioning that the fats we digest are not directly associated with the type of fat in our body. Once digested, dietary fats are broken down. Our liver then uses the digested parts to make its own unique fats. But research has shown that the type of fats we eat do affect what the liver makes.
Digestion:
Fats are absorbed in the small bowel. They are then transported to the liver in our blood vessels. The liver then uses dietary fats to make its own fat which is then transported to various organs via the blood vessels. The type of fat we eat affects the type of fat we make; some good and healthy and others bad and harmful.
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Dietary fats:
UNSATURATED FATS: The healthiest dietary fats. They have less hydrogen on their FAA chains.
Unsaturated fats are associated with decreased rate of cardiovascular disease and diabetes. They are found in natural products including:
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Legumes
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Avocado
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All kinds of nuts (no more than a handful per serving)
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Vegetable oils (one table spoon on salad)
You should try to include unsaturated fats in all your major meals. Just remember that they are very high in calories. So eat them in moderation. Nuts are great for snacking. For most people a handful (about 10 pieces) is plenty to keep you full and provide a good amount of healthy nutrition with enough calories. Vegetable oils are also an easy way to add unsaturated fats to your diet. Adding oil to your salad instead of pre-made commercial sauces is a great way to substitute a healthy choice for an unhealthy choice. One table spoon is all you need. A slice of avocado spread on your sandwich instead of mayo is another great way of replacing unhealthy fat with a healthy source.
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SATURATED FATS: simply have more hydrogen on their FAA chains. Our conception of saturated fats is rapidly evolving. Previously thought to be harmful, research now shows that saturated fat in certain natural products may in fact be beneficial. Saturated fats are found in:
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Dairy products
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Red Meat
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Poultry
You should limit your saturated fat intake to food products that have other healthy benefits. For the most part this includes dairy products and poultry.
There is some research associating red meat consumption with increased risk of colon cancer. The current thought is that red meat promotes growth of certain bacteria in the colon that increases the risk of colon cancer. So try to eliminate or reduce your red meat consumption to no more than 2 servings per week but using higher quality red meat (organic grass fed).
Dairy products are rich in healthy fats, protein, calcium and vitamins. 1-2 serving per day is all you need to reap the benefits (see Dairy section for more information).
TRANS (HYDROGENATED) FATS: a product created by artificially hydrogenating and changing the structure of natural fat, trans fats are very unhealthy and associated with increased risk of cardiovascular disease. They have NO place in your diet. Trans fats are more stable and have a longer shelf life, and they are also solid at room temperature. Therefore, they are used by the food industry to make various foods sold in stores. Always read the food label on the back on an item to make sure there are no trans (hydrogenated) fats. Some examples include certain brands of chips, deep fried food, pastries and margarine. Fortunately, due to stringent regulatory measures, the prevalence of trans fats has significantly decreased.
Breakfast:
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avocado spread on toast
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nuts mixed with bowl of oats (1/4 cup)
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peanut butter (2 tbs)
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eggs (2-3)
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flax seed (2 tbs)
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1 serving of a dairy product
Medical Application
Most adults at some point have had their blood drawn for a “lipid panel.” A lipid panel is a set of blood tests that measure the clinically important fats in your blood. Lipid is simply the medical term for fats. Our body has many lipid types, but clinically we only measure a few of them. There is for two reasons:
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We only understand these few and how they affect our health.
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Most of the research and drug developments are based on these few limited lipids (fats).
Some of you may have paid out of pocket to get a much more comprehensive lipid profile than what is typically ordered or paid for by health insurance. Unfortunately, all those extra numbers are cool to look at, but they have no clinical value. We simply do not know what they mean, how they affect our health, or how to change them. Having said that, here are the 4 numbers you need to understand from your lipid panel:
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LDL: low density lipoprotein. This is the harmful type of fat that gets deposited in your blood vessels and causes cardiovascular disease (heart attack and stroke). The lower, the better for the LDL. Generally we would like to see this number less than 120 in normal people and less than 70 for those with heart disease or history of stroke. This is the main target of the lipid lowering drugs you may have heard of (Lipitor, Crestor, Zocor, Pravachol and the like, called Statins as a group which the generic version ending in "statin").
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HDL: high density lipoprotein. This is the healthy lipid (fat). It works by removing harmful fats away from the blood stream and into the liver where they are broken down. Eating a healthy diet with unsaturated and omega fats seems to help. The higher, the better for HDL. Any value above 40 for men and 50 for women is considered good.
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Triglycerides: This is a transient complex structure that takes the digested food absorbed from your intestine to the liver for further metabolism. It also carries LDL lipids. Therefore the triglycerides can vary depending on when your last meal was and how fatty it was. Research has shown that elevated levels are associated with increase risk of cardiovascular disease. Omega-3 fatty acids reduce triglyceride levels. So if your triglycerides are above 200 consider eating fish 2-3 times a week.
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Total Cholesterol: This is the number that most people obsess about and quote when they are talking about their cholesterol levels. But this is a misnomer. Total cholesterol is not an actual level, rather it is calculated automatically by the lab using this formula: