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Macronutrients 3 of 3: Fat

Fat. It's the macronutrient we love to hate. It's in hundreds of foods, and if we eat too much, it can kill us. But do you know what fat does for the human body?

It provides us with energy. Fat has more than twice as many calories per gram as carbohydrates or proteins. When our bodies store energy, they do so primarily in the form of fat.

Technically speaking, what happens when we eat fat?

Fat enters your digestive system and meets with an enzyme called lipase. The lipase breaks fat into glycerol and fatty acids. These components are then reassembled into triglycerides to be transported in the bloodstream. Your muscle and fat cells absorb the triglycerides to burn as fuel or store for later.

Do we have to eat fat?

Yes. Fat-soluble vitamins require fat to be utilized by the body. There are essential fatty acids your body needs that it cannot produce on its own. Omega-3 and omega-6 are considered essential fatty acids.

What types of fats are there?

Saturated Fats

...are the "bad" fats. These fats are the primary dietary cause of high blood cholesterol. They're typically solid at room temperature and are found primarily in foods from animals and some plants. Here are some examples:

Animal Foods with Saturated Fat - Beef, butter, cheeses, cream, lamb, lard, milk (other than skim milk), pork, poultry fat, shortening and veal.

Plant Foods with Saturated Fat - Cocoa butter and tropical oils including coconut oil, palm kernel oil and palm oil.

Technical Trivia: Fatty acids are molecules composed mostly of carbon and hydrogen atoms. Saturated fat (or a saturated fatty acid) has the highest possible number of hydrogen atoms attached to each carbon atom. It is "saturated" with hydrogen atoms.

Unsaturated Fats

...are the "good" fats. It's believed that unsaturated fats can help lower your blood cholesterol levels, but that doesn't mean you should eat more of them. You should only eat them in place of saturated fats you already consume.

Unsaturated fats are broken down further into Polyunsaturated and Monounsaturated fats. Polyunsaturated oils are liquid at room temperature and in the refrigerator. Monounsaturated oils stay liquid at room temperature but start to solidify at refrigerator temperatures. Unsaturated fats are primarily found in oils from plants.

Monounsaturated Fats - Avocado, canola, olive and peanut oils.

Polyunsaturated Fats - Corn, safflower, sesame, soybeans, sunflower seeds, many nuts, seeds and their oils.

Technical Trivia: If a fatty acid is missing a pair of hydrogen atoms in the middle of the molecule, that gap is called an "unsaturation," and the fatty acid is "monounsaturated." Mono, meaning single or one. If more than one pair of hydrogen atoms are missing, the fatty acid is "polyunsaturated." Poly meaning multiple or many.

What are trans fatty acids or trans-fats?

These are solid fats created by heating liquid vegetable oils in the presence of metal catalysts and hydrogen. During the procedure, some of the missing hydrogen atoms are put back into polyunsaturated fats. The process is called hydrogenation. The idea behind it was to create a food with all the cooking properties of saturated fats but the health benefits of unsaturated fats.

It didn't work. Fats that have been hydrogenated have been shown to raise blood cholesterol and are at least as bad for you as saturated fat. Margarine and vegetable shortening are examples of hydrogenated fats, and you can find them in many commercially produced baked goods and snack foods. The National Institute of Medicine has determined that there are NO safe levels of trans fats in the diet.

Note: Animals produce small amounts of trans fat naturally, so low levels can be found in dairy and beef fat, lamb and pork.

Fat  |  WeBeFit.com Quick Card (c) 2006
Unsaturated Fats Saturated Fats Trans-fats
Unsaturated fats are broken down into Polyunsaturated and Monounsaturated fats. Polyunsaturated oils are liquid at room temperature and in the refrigerator. Monounsaturated oils stay liquid at room temperature but start to solidify in the refrigerator.

15-25% of your diet should consist of fat, preferably the unsaturated kind.
They're typically solid at room temperature and are found primarily in foods from animals and some plants.

Limit saturated fats in your diet because they are the primary dietary cause of high blood cholesterol.
Solid fats that are created by heating liquid vegetable oils in the presence of metal catalysts and hydrogen. Avoid Trans-fats in all processed foods.
According to The National Institute of Medicine, there are no safe levels of trans fats in the diet.
Green - Best Choice | Yellow - Proceed with Caution | Red - Avoid

How much fat is acceptable?

The American Heart Association recommends that healthy Americans over the age of 2 limit their saturated fat between 7-10 percent of total calories. Total fat intake shouldn't exceed more than 30 percent of total calories.

To figure out how many grams of fat you can eat, you will need to know how many calories you should eat in a day. If you already know, put that number in the TOTAL DAILY CALORIES part of the formula below. If you don't, learn how to estimate how many calories you need every day by reading our Resting Metabolic Rate article. Click Here for the full article.

Calculate Fat Grams

TOTAL DAILY CALORIES (multiplied by) 30% = Maximum Fat Calories
Maximum Fat Calories (divided by) 9 = Maximum Acceptable Fat Grams Daily

Click here, and we'll calculate how much fat you can eat in a day.

Another option is to calculate how much fat is in food before buying it at the grocery store. Limit your foods to things that are 30% or less fat. As long as you keep your calories under control, the fat should be ok. To calculate the Fat Percentage of foods, use the following formula.

Fat Percentage of Foods

Take the total FAT GRAMS and multiply by 9. Then DIVIDE the total by the TOTAL CALORIES and the percent key (instead of equals). Now you know the true FAT percentage of a food.

Example: If a food had 210 calories and 3 grams of fat.

Fat Grams 3 (multiplied by 9) = 27
27 (divided by Total Calories) 210 (%) is 12.85% fat.

Don't be fooled! The % sign that appears to the right of the Total Fat on the nutrition label is NOT the fat percentage of that food. It is the percentage of fat that a single serving of that food contributes toward a 2,000 calorie a day diet. To calculate the fat percentage each food contains, you must use the Fat Percentage of Foods formula above.

Are there fat substitutes?

Yes. They are ingredients that mimic one or more of the roles of fat in food. According to the FDA, they are grouped into two categories. Food additives and "generally recognized as safe" (GRAS) substances.

Food additives must be evaluated for safety and approved by the FDA before they can be used. Examples of food additives include carrageenan, olestra and polydextrose.

GRAS substances don't require testing before being used in foods, typically because of the substances' long history of safe use in food. Examples of GRAS substances include dextrins, fiber, gums and starch.

Fat substitutes are further broken down into three categories based on their macronutrient source.

Carbohydrate-based - These use plant polysaccharides in place of fat.
Protein-based - These are used as fat replacers.
Fat-based - These are designed as barriers to block fat absorption.

Are fat substitutes safe?

The FDA has ruled that any approved food additives are considered safe. Currently, any long-term benefits or potential dangers are unknown.

The Tale of One Fat Substitute...Olestra (Olean)
(Olestra is a fat-based food additive.)

Developed by Procter & Gamble Co., Olestra adds no fat or calories to food because of its unique chemical composition. Sounds good until you read the side effects. Foods that contained Olestra were required to carry the warning that it could cause "...abdominal cramping and loose stools. Olestra inhibits the absorption of some vitamins and other nutrients. Vitamins A, D, E, and K have been added." A line of potato chips was released called WOW! and the marketers went into full swing. Eat all you want without guilt! WOW!

By October, 2004 the Food and Drug Administration (FDA) had received more than 20,000 Olestra-related reports of adverse reactions...more than for any food additive in history. The reports mostly involved diarrhea, gas and cramps. All for some potato chips!

Was Olestra taken off the market?

Nope. By the end of 2004, WOW! Chips were rebranded and called Lays's Light, Ruffles Light, Doritos Light, and Tostitos Light. Before you buy any food, you should read the label and consider yourself warned. If it looks too good to be true, it probably is. Wow.

How can I eat healthier AT HOME?

  • Avoid foods like cookies, crackers, doughnuts, french fries or anything deep-fried. These foods typically are high in fat, and many are also high in trans-fats.

  • Switch from whole and 2% milk to 1% or fat-free.

  • Don't buy organ meats like brain, kidney, liver and sweetbreads.

  • If you eat ground beef, choose 93% lean or leaner. Consider alternatives like lean ground turkey, ostrich or buffalo meats.

  • Choose processed foods made with unhydrogenated oil instead of hydrogenated or saturated fat.

  • Use soft margarines (liquid or tub varieties) instead of the harder stick forms or butter. The label should say "trans-fat free."

  • Use non-fat yogurt or fat-free sour cream for dips, sauces and pie toppings.

  • Eat chicken and turkey without the skin.

  • Cook stews and boiled meat a day in advance and refrigerate them. The next day you can skim the fat from the top before you heat them for serving.

How can I eat healthier DINING OUT?

  • Just say no to appetizers that are battered, breaded, deep-fried or covered in sauces.

  • Breakfast - Hot or cold cereals. Scrambled egg whites or egg substitute. Tomato slices instead of hash browns. Pancakes (without butter) and sugar-free syrup. Whole wheat toast dry (no butter).

  • Chinese - Stir-fried vegetables. Hunan, Szechuan shrimp, or chicken. Avoid the beef, pork and deep-fried ingredients.

  • Deli or Sandwich Shops - choose turkey or chicken (without skin) and mustard. Skip the mayo.

  • Fast Food - Barbecue or grilled chicken breast. Ask for the mayo to be left off.

  • Italian - Spaghetti with tomato or meat sauces. Linguini with red sauce.

  • Mexican - Vegetable or chicken fajitas. Chicken or bean burritos and chicken tacos.

  • Salads Anywhere - Watch out for what gets dumped on top. Cheese, meat, croutons and dressings can change a low-calorie meal into a high-fat disaster. Ask for the fat-free or light dressings and get them on the side.

  • Seafood Restaurants - Broiled or grilled fish and baked or steamed veggies are better than breaded and fried.


In the January 28, 2005 issue of Cell, scientists announced they had finally identified the mechanism that causes foods rich in saturated fats and trans-fatty acids to elevate blood levels of cholesterol and triglycerides and increase one's risk of heart disease and certain cancers.

Researchers led by Bruce Spiegelman, PhD at the Dana-Farber Cancer Institute made the breakthrough.

The report states that the harmful effects of saturated and trans fats are set in motion by a biochemical switch in liver cells called PGC-1beta.

Before this study, scientists were aware that saturated and trans fats caused increases in blood cholesterol and triglycerides but didn't know the mechanism behind it. By now knowing how it occurs, researchers can develop treatment options to reduce or even potentially reverse the negative effects.

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  • Saturated Fat Goes Straight to Your Gut

    Researchers have now confirmed that saturated fat builds more FAT and less MUSCLE than polyunsaturated fat. In it’s first of a kind study on humans, researchers demonstrated that the fat composition of food influenced cholesterol levels in the blood, cardiovascular disease risks and helped determine where fat was stored in the body.

    Subjects who gained weight on excess calories from polyunsaturated fat had greater gains in muscle mass and less body fat, than subjects who ate the same number of calories in saturated fat.

    Don’t fall for articles and gimmicks that claim “ALL FAT IS GOOD.” As we’ve always recommended, fat should be eaten in moderation, primarily from unsaturated or “good fat” sources.