Healthy Eating Fats - The Science
Fat is the popular name for the organic compounds that scientists generally refer to as “lipids, ” but for our purposes, we will use the term fats, rather than lipids to refer to all of the lipid family, including triglycerides (fats and oils), sterols (like cholesterol) and phospholipids (such as lecithin).
Triglycerides and fatty acids
Triglycerides are the fats in your food, the fats in your body, as well as the liquid fats, a/k/a “oils. ” They are made up of glycerol and fatty acids and are the main source of fat in your diet.
Essential Fatty Acids
Your body can manufacture all but two of the fatty acids it needs,Omega-3 and Omega-6, and so these are called “essential fatty acids,” because you must get them from your diet. Fatty acids come in the saturated variety and the unsaturated variety, hence the terms “saturated fat” and “unsaturated fat” that you hear about so often in the news.
To explain the difference between saturated and unsaturated fats in scientific terms, you need to know that there are bonds or links between the atoms of carbon and hydrogen in a fatty acid molecule. When all of the available bonds are taken by hydrogen atoms, we say the fatty acid is “saturated”—meaning all the hydrogen atoms that can be present in that molecule, are present.
These saturated fatty acids are very stable; that is to say they are difficult to change, because they do not have any open or double bonds where the changes could easily occur. When the triglycerides in a fat are composed mainly of these saturated fatty acids, we say that it is a saturated fat.
If, however, a fatty acid has some bonds that are doubled up or available, we say that it is “unsaturated”— meaning that not all of the hydrogen atoms that could be present are present. This means the fatty acid is more unstable and easier to change, because it has places--these open or double bonds-- where change can easily occur. When the triglycerides in a fat are mostly composed of these unsaturated fatty acids, we say that it is an unsaturated fat.
Meet Mono- and Poly-
The unsaturated fats are divided into two groups—monounsaturated, (sometimes popularly called "MUFAS") which are composed mostly of fatty acid molecules that have only one double bond where hydrogen atoms could attach, and polyunsaturated fats, which have molecules of fatty acids with two or more of these double bonds, allowing for many hydrogen atoms to attach and thus change the molecule.
Can you guess which of these types are more unstable?
You’re right. The polyunsaturated fats are more unstable, since more activity and change can occur because of numerous open spots on the chain.
How do Saturated and Unsaturated Fats affect your health?
This is important to you because of the role that saturated and unsaturated fats play in your diet and in your health. Saturated fats, because they are so stable, tend to be harder to digest or to breakdown, while unsaturated fats, because they are unstable, tend to be easier to digest and are less likely to collect in inconvenient places in your body.
Saturated fats are also implicated in a rise in LDL levels (otherwise known as the “bad” cholesterol) in the blood.
Conversely, saturated fats, again because they are more stable, tend to have a longer shelf life, while the unsaturated fats, being less stable, can more easily become rancid (spoiled).
There has been some research recently to suggest that the unsaturated fats, particularly the polyunsaturated ones, may have worse implications for your health than saturated fats because, in their instability, they produce compounds that may be harmful to the body. Stay tuned!
Another type of fatty acid is what scientists call “trans-fatty acids” or trans-fats. These are fatty acids that are arranged chemically in such a way that they act more like a saturated fat than an unsaturated fat and seem to have harmful effects on the body.
The most common source of trans-fats is hydrogenation, a process in which hydrogen is added to an unsaturated fat to make it more stable, giving it a longer shelf life and a more pleasing texture.
An example of a hydrogenated food is peanut butter. Most peanut butters have been hydrogenated to make them more spreadable and able to be stored without refrigeration. So-called “old fashioned peanut butter” does not undergo this process, so it has a less creamy texture and should be stored in the refrigerator.
Another commonly hydrogenated food is margarine. Hydrogenated fats are often used in commercial baked products to increase their shelf life.
Although, triglycerides are the most common fats, it is safe to say that the sterols, particularly cholesterol, are the most notorious. These organic compounds have a different structure than the triglycerides and therefore, function in a different way in the body. The body can produce them or they can come from the foods you eat.
Although they have gotten a lot of bad press, sterols, including cholesterol are necessary for good health. It is when cholesterol collects in the arteries that it becomes the bad guy—potentially leading to heart attacks and strokes.
It is important to note that the dietary factor most affecting your cholesterol level is the amount of saturated fat you eat and not the amount of cholesterol in your food.
The third groups of fats are the phospholipids. These are organic compounds that are similar to triglycerides, but with phosphorus and a nitrogen component, which allows them to be soluble in both water and fat. The most notable phospholipid is lecithin, an emulsifier, which, although present in some foods, can also be manufactured by the liver.
Healthy Eating Fats - The Scoop
Whew! That may be as close to organic chemistry as you ever want to get! In spite of the recent taboos placed on fats, without them you cannot maintain a healthy lifestyle. However, you may want to be aware of the type and quantity of fats you are eating.
Saturated fats are solid at room temperature. There are some animal sources of saturated fat:
Butter… Lard… Visible fat in red meat… Skin fat in poultry… Fat in Lunchmeats… Fat in Sausage…
And the tropical “oils” from plants:
Coconut oil… Palm kernel oil… Cocoa butter… Palm oil…
Unsaturated fats are divided into monounsaturated oils:
Olive oil… Canola oil… Peanut oil…
And the polyunsaturated oils:
Safflower oil… Sunflower oil… Corn oil… Soybean oil… Most “Vegetable” oils…
There is also a significant amount of fat, of the saturated variety, in many dairy products:
Cheese… Milk… Cream… Yogurt… Ice cream… Sour cream…
Fewer saturated fats
It is generally recommended that to be healthy eating fats, choose fewer saturated fats, and in the case of dairy products, that you opt for the low fat version, particularly if you are trying to lose weight.
MY TWO CENTS about Healthy Eating Fats
Be aware that if the fat content is lowered in products such as yogurt and ice cream, it may be replaced by ingredients that are not necessarily better for you than the fat. Since it is often the fat that gives food its texture and flavor, when the fat is removed it may be replaced with chemicals or extra sugar to improve the flavor.
Thus, it may be better to eat smaller amounts of the whole food, rather than a version that has been adulterated in an unhealthy way. Of course,this does not apply to foods that merely have the fat removed with nothing else added, such as low-fat or skim milk and plain yogurt, but you will lose flavor and satiety with the removal of fat.
Rule of thumb
With regard to cheese, a rule of thumb to remember is the harder the cheese, the more saturated fat. Thus cottage cheese has less saturated fat than a sturdy cheddar or a robust Swiss.
Fats are also found naturally in foods that you don’t normally associate with the fat group. These include the following:
Nuts... Seeds... Avocados... Olives...
Most other vegetable food sources contain little or no fat, unless it is added during preparation.
What about cholesterol?
Cholesterol is found almost exclusively in animal foods:
Meat… Eggs… Poultry… Shellfish… Dairy Products…
Other sterols are found in all plant foods and seem to be useful in lowering the level of cholesterol in the blood.
Emulsifiers in the fat group
Lecithin is the most commonly known emulsifier, and is found naturally in foods such as eggs, wheat germ, liver and soybeans. It is also added to many processed foods, such as mayonnaise, since it allows oil to mix with other liquids.
It has been popular as a diet food, but since the liver can make all of the lecithin it needs, it is questionable whether taking lecithin as a supplement is really useful. In addition, there can be some uncomfortable side effects from taking large doses, such as digestive distress.
Omega-3 and Omega-6
There has been a lot of press about the importance of the essential fatty acids, Omega-3 and Omega-6. It has been suggested that many people, while getting enough Omega-6, are deficient in Omega-3.
The main sources of Omega-6 are meats and vegetable oils, with Omega-3 being found in nuts, seeds and fish. If you are a vegetarian, a good source of Omega-3, is freshly ground flaxseed.
Healthy Eating Fats - The Science
There has been so much change and controversy surrounding the issue of fat in the diet, that it is difficult to answer the question of how much fat you need. However, If you live in the U.S., it is probably safe for most people to answer this question by saying, “Less than you are eating!!”
There is a not an RDA for fat, and for most people it is more a question of reducing fat intake than trying to get enough. Having said that, it is generally recommended that you get at least 20%, and no more than 30% of your calories from fat.
Keep in mind that fat provides more than twice the calories of protein and carbs, 9 calories/gram, so it takes less fat to get to your goal of 30% or less. If you eat a 2400-calorie diet, no more than 720 of those calories should come from fat. At 9 calories per gram, that would be about 80 grams of fat.
2400 calories x 30% = 720 calories
720 calories ÷ 9 calories/gram = 80 grams
This sounds like a lot of fat, but if you check food labels, you will find that fat grams can add up fast, especially if you are eating a lot of “fast food."
A deluxe hamburger or cheeseburger from a fast food restaurant may have 40-60 grams of fat. When you add a large order of fries, you may reach or exceed your fat limit for the day in just that one meal, and that’s without the chocolate shake!
The USDA food guide recommends that you get 10% or fewer of your calories from saturated fat. This means that for a 2400-calorie diet, only 240 calories, or 26 grams of fat should come from a saturated fat source.
To put this in perspective, one pork chop could just about provide all the saturated fat for the day, and the fast food meal described above has enough saturated fat for several days!
The food guide also recommends that you keep your cholesterol consumption under 300 mg/day and keep trans-fats as low as possible. The main sources of cholesterol in your diet are meat, eggs, shellfish and dairy products.
Trans-fats are found in deep-fried foods, margarine, imitation cheese, most processed baked goods, such as cakes, cookies, pastries and doughnuts, chips and some dairy products and meats.
Healthy Eating Fats - The Scoop
There is no question that you need fat in your diet. It is probably better to get as much of your fat from plant foods as you can. Use animal foods such as meat, cheese and butter sparingly and limit fried foods, as well as whole fat dairy products.
When choosing meat, it is generally recommended that you choose the leaner varieties, (although the fat in meat is what makes it “juicy,” so you may want to limit your portions instead, or eliminate just the visible fat).
Olive oil wins the prize
Many health experts are recommending that we use olive oil for cooking instead of other types of vegetable oils. Since it is mostly monounsaturated, it is less likely to turn rancid and it remains fairly stable at high cooking temperatures.
Be sure to choose extra virgin olive oil that has a nice fruity smell and a green color. The use of olive oil has been suggested as one of the reasons that the Mediterranean style of eating, in spite of being high in fat, is not associated with the high incidence of heart disease that is connected with the typical American diet.
The polyunsaturated oils, which have been so popular, are not bad in themselves, but if they are not handled properly they are more likely to breakdown into substances that are not good for you.
Fun Fact for Healthy Eating Fats: Did you know that avocados are an excellent source of monounsaturated fat? They are also rich in fiber and vitamins and minerals such as Vitamin A, folic acid and potassium. Try mashing a fresh avocado with some sea salt and lemon juice for a great dip for veggies, or put slices of this “buttery” fruit on a sandwich or chunks of it in your favorite garden salad. Delicious!
It is sometimes difficult to see the fat in your diet. There are, of course, the obvious sources like butter, margarine or that strip of white stuff on your steak.
It is the invisible fats, however, that tend to sneak up on you and can put you in fat overload--that doughnut or muffin that was the birthday treat at the office this morning, the chocolate bar you had for your 3:00 snack, that little bag of chips or peanuts you munched on while you were driving home from work.
The daily recommendations for being healthy eating fats include all of the sources of fat in your diet and not just the visible fats. This is not to say that you should not ever eat chocolate, or chips, but be aware of their impact on your total fat intake for the day.
Some easy ways to cut invisible fat from you diet are:
-Eat your cooked vegetables without butter or cheese sauce…
-Limit fried foods, especially deep-fried, in your diet…
-Substitute a piece of fresh fruit for a snack, instead of chips…
-Eat raw nuts such as almonds instead of oil-roasted nuts…
-Leave the cheese off of your burger…
-Use salad dressing sparingly…
-Eat tuna packed in water instead of oil…
-Have a bagel (whole grain, would be nice) instead of a croissant or muffin (use cream cheese sparingly, a little goes a long way!!)
Fat provides flavor and satiety. Without it, many foods would lose their savor and you would find yourself hungry all of the time.
One of the advantages of eating a meal or snack with some fat in it is that it takes more time to get through your digestive system, which means you feel satisfied longer.
Aside from these gustatory advantages, fats, along with protein and carbs, provide energy, both at the time the fats are eaten and later when released from storage in your body.
You would miss that cushion!
While the fat is in storage under your skin, it keeps you warm and cushions your body from life’s bumps and shocks.
Fats also form an important part of the structure of cell membranes, facilitate the passage of hormones and certain vitamins in and out of the cells, and are part of the make-up of important compounds in the body such as bile acids and hormones.
What if I don’t get enough fat?
This is not a problem for most people in developed countries, unless they are living in poverty and not getting enough to eat. However, some people put themselves on strict, low fat diets or have eating disorders that cause them to eat too little fat.
As with any of the nutrients, if you do not get enough fat, you will lack energy and ultimately, your overall health will be affected. All of the nutrients work together to keep you feeling well, including fat.
What happens if I eat too much fat?
You probably already know the answer to this one. If you eat too much fat, you will probably get fat. In addition, even if you are not overweight, if you eat too much fat, especially of the saturated or trans-fat kind, you will be at a higher risk for all those diseases you hear about, including heart disease, diabetes and certain types of cancer.
One other side effect of a high-fat diet is that you may suffer from indigestion, particularly if you have had your gall bladder removed.
It seems the older you get, the less tolerance you will have for high fat foods.
Healthy Eating Fats - The Secret
Eat more plant foods. Cook with olive oil. Choose leaner meats in smaller portions and include fish. Watch out for those trans-fats and tropical oils. Pick lower fat versions of dairy products(unless the fat has been replaced with sugar or chemicals). Be aware of the invisible fats in your diet.
You can be healthy eating fats, if it’s the right kind!
Test your knowledge of Dietary Fats. Click on the link below.