Good fats, bad fats, saturated, unsaturated, mono, poly, trans, omegas, cholesterol... are they trying to make this stuff confusing?

First of all fat is not bad! Your body needs fat. Fat is crucial to the development of healthy cells, particularly in the brain and nervous system. Body fat cushions your internal organs and keeps you warm.

Dietary fat transports important fat-soluble vitamins (A, D, E & K) and provides essential fatty acids. Plus, let's face it, fat tastes good and makes our food more satisfying.

Fat is the most concentrated source of energy. One gram of fat contains 9 calories, while carbohydrates and protein only contain 4 calories per gram. Having a concentrated energy source was important when our ancestors spent their days chasing prey across the plains.

However, in an environment of cheap, abundant food and inactive lifestyles, too much fat contributes to obesity and disease. It doesn't help that the least desirable kinds of fats (the one's that cause the most health problems) are the most abundant in our food supply.

How Much Fat?
The current recommendations are to consume no more than 30% of your total calories from fat and 10% of your total calories from saturated fats (mostly animal fats). For an individual who consumes 2500 calories per day, this translates to 750 total fat calories of which only 250 should be saturated fat. See the box at left to estimate your calorie and fat recommendations.

However, these figures aren't carved in stone. There are cultures that eat much less fat (most of Asia) and cultures that eat more (much of Europe) and neither have the high levels of obesity or heart disease that Americans do. This leads us to believe that it's not just the amount of fat, but the type of fat, the overall diet, and other lifestyle factors that make up the whole picture.

Now 750 calories may sound like a lot of fat until you realize that 1 tablespoon of fat has about 130 calories. So that's a total of less than 6 tablespoons of fat per day of which less than 2 tablespoons should be saturated fat.

If you have a burger, fries and milkshake for lunch you've had your fat allowance for the entire day, far exceeded the saturated fat recommendation, and probably consumed some trans fats (we'll talk about those below). Same if you have a steak, baked potato with butter and sour cream, and a salad with thousand island dressing for dinner.

Chances are that if you're not really trying to limit your fat consumption, you'll be over the 30% total and way over the 10% saturated fat recommendation.

What Kinds of Fat?
Now that you know how much fat you should have, let's try to shed some light on the types of fats.

Unsaturated Fats
Unsaturated fats don't increase LDL cholesterol levels and therefore aren't linked to increased risk of heart disease. For this reason unsaturated fats are often referred to as "good" fats.

Unsaturated fats are found primarily in the oils from plants. Polyunsaturated and monounsaturated fats are the two types unsaturated fats (see box at left).

Monounsaturated fats include, canola, olive and peanut oils and avocado. Polyunsaturated fats include corn, safflower and sesame oils, soybeans, and many nuts and seeds, and some fish.

Polyunsaturated fats tend to help your body get rid of newly formed cholesterol. Thus, they keep the blood cholesterol level down and reduce cholesterol deposits in artery walls. Recent research has shown that monounsaturated fats may also help reduce blood cholesterol as long as the diet is very low in saturated fat.

Omega 3 and Omega 6 fatty acids are two types of polyunsaturated fats. Both are essential for human health, because the body can't produce them... you must consume them. Omega 6 is fairly easy to consume in a typical diet and is found in olive oil, most vegetable oils, eggs, and poultry.

Sources of Omega 3 are less common and include salmon, tuna, mackerel, walnuts, flaxseed oil. Research suggests that Omega 3 oils are can reduce the risks of heart disease, lower blood pressure, and boost immune function. For this reason, you may see foods, such as eggs and margarine with added omega 3 oils and Omega 3 supplements (fish oil capsules).

Saturated Fats
Saturated fats are mostly from animal sources (meat, cheese, milk). These animal fats also contain cholesterol, which we'll discuss later. Saturated fats are a concern, because they raise blood LDL cholesterol and this increases your risk of heart disease.

The few plant sources of saturated fat are referred to as tropical oils and include palm and coconut oils. These oils are found mostly in store-bought cakes, cookies and snack foods. Many food companies have taken tropical oils out of their products due to health concerns, but in many cases they replaced them with vegetable fats high in trans fatty acids, which may actually be worse.

One easy way to identify saturated fats is that they are typically solid at room temperature compared to unsaturated fats that are liquid (oils) at room temperature. If you want to know why fats are called saturated or unsaturated, see the box at left.

Hydrogenated Fats
The problem with unsaturated fats is that they react with oxygen and deteriorate to the point that they taste bad (rancid). This isn't typically a problem with foods prepared at home, but it is a problem for food manufacturers who want a cupcake or corn chips to still taste good after a year or restaurant owners who want to buy cheap oil in bulk and have it last a long time.

Food manufacturers addressed this issue by hydrogenating unsaturated fats to increase their stability and make them solid at room temperature. These fats are listed as hydrogenated or partially hydrogenated oils on food labels.

Margarine and shortening (Crisco) are examples of hydrogenated fats. These products are made from oils that would normally be liquid at room temperature. The idea was that these products would be better than butter or lard, which are high in saturated fat and perishable. However, it turns out that the hydrogenation process creates trans fats that may be more harmful than saturated fats.

Trans Fats
Trans fats are formed when vegetable oils are partially hydrogenated to make them more solid and less perishable. Trans fats are found in many products, including vegetable shortening, margarine, French fries, donuts, and baked goods, cookies, crackers, cereals, candies, granola bars, chips, snack foods, salad dressings, and many other processed foods.

Although trans fats are unsaturated, research suggests that trans fats may be even more artery clogging than saturated fats. The Food and Drug Administration requires trans fat to be listed on the nutrition label effective 2006. Many food manufacturers have already started listing trans fat and some have eliminated trans fat from their products.

Trans fats are unsaturated, but they can raise total and LDL ("bad") cholesterol and lower HDL ("good") cholesterol. Trans fats result from adding hydrogen to vegetable oils used in commercial baked goods and for cooking in most restaurants and fast-food chains.

Unfortunately, there are no labeling regulations for fast food. Eating one doughnut at breakfast and a large order of french fries at lunch totals 10 grams of trans fat.

Cholesterol
Cholesterol plays important roles in your body. Cholesterol helps maintain cell membranes and is used to produce some hormones. However, too high a level of blood cholesterol is a major risk factor for heart disease.

High cholesterol in your diet, as well as high saturated and trans fat, increase blood cholesterol levels and increase the risk of heart disease and stroke. Cholesterol is found only in animal products, such as meats, fish, eggs, and dairy products.

Cholesterol intake should be limited to less than 300 milligrams per day. One egg contains about 200 milligrams of cholesterol. You can see why a daily breakfast of two fried eggs isn't a great idea, especially if accompanied by bacon and buttered toast.

Fat Substitutes
Fat substitutes seem like a dieter's dream... the taste and texture of fat, but with fewer calories. Some fat substitutes are made from carbohydrates (modified starches, dextrin, cellulose and gums) or protein (Simplese from skim milk). The substitutes are fully absorbed, but provide only 4 calories/gram instead of the 9 calories/gram in fats.

Carbohydrate and protein based fat substitutes are considered safe, but it's important to remember that these are not calorie free foods and can still contribute to weight gain if over consumed.

Other fat substitutes, such as Olean (Olestra in potato chips) are not absorbed and therefore provide no calories. This may sound even better, but when food goes through your system unabsorbed it can cause some unpleasant side effects, including cramping and loose stools.

In addition, these fat substitutes reduce the absorption of fat soluble vitamins as they pass through your system. For this reason, foods that contain unabsorbable fat substitutes are required to be fortified with vitamins A, D, E and K.

So, How Should I Eat?
Now that you know how much and what kind of fats, let's look at what this really means for your diet. The bottom line is that most people need to make an effort to reduce fat in their diets, because fats contain a lot of calories. In addition, special effort should be made to limit saturated fats, trans fats and cholesterol due to their roles in the development of heart disease.

  • Limit your consumption of fried foods... French fries, fried chicken, and fried clams are pretty obvious (the word "fried" is a dead giveaway!), but potato chips, tortilla chips, egg rolls, chicken nuggets, onion rings, and donuts should also be limited. Basically any food that is dunked in hot fat is going to have a high fat content and probably contain trans fats.
  • "Cream" is another word that indicates high fat content, as in ice cream, whipped cream, cream cheese, cream soups, and cream sauces. Look for low-fat versions of dairy products and broth or vegetable based soups and sauces.
  • Choose lean meats, such as chicken and turkey and remove the skin. Choose extra lean ground meat instead of hamburger. Use smaller portions of meat and combine with vegetables (stir frys and stews).
  • Use beans instead of meat in soups, chili, and Mexican foods. They're low-fat and provide protein and fiber.
  • Look for low-fat dairy products, such as skim or low-fat milk and low-fat ice cream or frozen yogurt. Use non-fat plain yogurt instead of sour cream.
  • Most cheeses are high in fat. Look for cheeses made with skim milk, such as low-fat mozzarella. Cheeses like bleu and sharp cheddar are high in fat, but have a lot of flavor, so you may use less.
  • Limit baked goods (cakes, pies, and pastries) that are high in fat. Look for low-fat versions, but still watch your portion size.
  • Limit high-fat salad dressings (bleu cheese and thousand island) or use lower fat versions.
  • Use no-stick cooking pans and saute in water, broth or wine instead of fat. Instead of sauteing in butter, use olive or canola oil. The calories are the same, but there's less saturated fat.
The Bottom Line

Limit total fat to 30% of daily calories

Limit saturated fat to 10% of calories

Avoid trans fats commonly found in snack foods

Unsaturated fats, including vegetable oils, nuts and seeds, are good choices

Limit cholesterol to 300 mg/day

Don't overeat foods, just because they are fat-free or reduced fat.
How much fat should I eat?

The recommended amount of fat depends on how many calories you need.

An easy way to estimate your calorie needs is multiply your weight (in pounds) by 13, if you aren't physically active, and by 15, if you are active.

If you weigh 180 lbs and aren't very active, you'll need about 2340 calories per day (180 x 13) to maintain your current weight.

No more than 30% of your calories should come from fat and only 10% from saturated fat.

For a 2340 calorie diet, that's 702 calories (2340 x .30) total fat of which no more than 234 calories (2340 x .10) should be in the form of saturated fat.
Why are they called saturated and unsaturated fats?

Because of the chemical structure. Fats have a carbon chain that can contain either single or double bonds between the carbons.

Fats that have all single bonds are referred to as saturated fats, because they have the maximum number of hydrogens on each carbon (saturated with hydrogens).

Unsaturated fats have double bonds between some of the carbons and are therefore not totally saturated with hydrogen and are referred to as unsaturated.

If a fat has one double bond in the entire carbon chain, it is called monounsaturated. If it has more than one double bond, it's called polyunsaturated.

Omega 3 and Omega 6 fats are types of unsaturated fats. Omega 3 fats have the first double bond on the 3rd carbon in the chain and Omega 6 fats have the first double bond on the 6th carbon.

I hope this didn't bring back bad memories of your highschool chemistry class!
Why am I suppose to eat fatty fish?

Yes, I know it doesn't sound right, but fatty fish (salmon, tuna, and mackerel) have those important omega 3 fatty acids that are hard to get in our diet and provide important health benefits.

Note: fried fish is not the good kind of fatty fish!
Why are they called trans fats?

Sorry, but the answer is another chemistry lesson!

Unsaturated fatty acids can either be in a "cis" or "trans" configuration. In the cis configuration the hydrogens on two double bonded carbons are on the same side of the molecule. In the trans configuration the hydrogens are opposite sides.

Why does this matter? Because our bodies don't seem to handle the trans fats very well. Research indicates that trans fats may be more artery clogging than even saturated fats.

Which is better... butter or margarine?

The trans fats in margarines have raised concerns that margarine may have more adverse health effects than butter.

The American Heart Association recommends soft margarines (liquid or tub instead of stick) , especially those labeled "trans-fat free".
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Men's Diet Sense provides general nutrition information and education. Specific medical advice should be obtained from a licensed health care practitioner. Consult your physician before you begin a diet or exercise program.
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