Dietary Fat: The Good, The Bad, and the Ugly

A Few Fat Facts

• Chemical family name for fats and related compounds is lipids

• Word lipos = Greek word for fat

• Fats are very high energy nutrients

Do Any of these look good?

"We’re hardwired to hunger for fatty, sugary, salty foods because, back when our ancestors were foraging for every meal, palatable eats meant extra energy and a leg-up on survival."

Dr. David A. Kessler, author of The End of Overeating: Taking Control of the Insatiable American Appetite

How Your Body Uses Fat

Visible Body Fat:• Source of stored

energy• Gives body shape• Cushion (need some

fat on your buttocks to sit!)

• Reduces heat loss (insulation blanket)

Your Body Also Uses FatKind of like bubble wrap for your guts!

Invisible (internal) body fat:

• Part of every cell including neurons

• Shock absorber to protect internal organs

• Part of hormones and other biochemicals

How does our body get energy from fat?

Well, picture a chain of long balloons…

When you drop a balloon into water

It floats! That’s exactly what happens when you swallow fat-rich foods.

The fat floats on top of the watery food-and-liquid mixture in the stomach.

Okay…not related…but isn’t that a really FAT cat?!!

Back on topic…Since the fat floats

This limits the effect that fat-busting digestive enzymes can have on it.

Because fat is digested more slowly, you feel fuller longer after eating high fat meals.

After a meal like one of these, you might say: “I feel full…way too full…urp!”

Break it down…

When fat moves down your digestive tract into your small intestine, a hormone signals your gallblader to release

BILE

Bile is an emulsifier, a substance that allows fat to mix with water.

Fatty Acids

The bile helps to break down the fat into fatty acids.

These can be used as a source of energy

Our body prefers using carbohydrates (since glucose is easier and more efficient) and will only burn fat when other available energy sources have been used up.

How Much Fat is Too Much?

Too much fat = increased risk of obesity, diabetes, heart disease and some forms of cancer (especially colon cancer)

But what about too little?

Infants and children

need fat to thrive.

Everyone needs some fat to absorb fat-soluble vitamins that smooth the skin, protect vision, bolster the immune system, and keep reproductive organs functioning.

No More than…

In 2005, Dietary Guidelines for Americans recommends no more than 20% to 30% of total calories from fat.

For a diet of 2000 calories per day, that =

400 to 600 calories

.

But are all fats equal?

No…and it all comes

down to chemistry.

Fatty acids are the building blocks of fats.

A fatty acid is a chain of carbon atoms with hydrogen atoms attached to the carbon.

But what does that have to do with what kind of fat I should eat?

The more hydrogen atoms, the more saturated the fatty acid.

Saturated, unsaturated, or trans fat all have different types of fatty acids.

“EEK!! I still want to know what does this have to do with me and my food choices?!!”

Saturated Fat

Appears as a "waxy" or solid fat at room temperature.

What would it look like on your inside as it contributes to the fatty cholesterol build-up inside your arteries?

Sources of Saturated Fat

• Beef, veal, lamb, pork and poultry.

• Lard, butter, whole milk, cheese

• Tropical cooking oils such as palm and coconut.

Should I eat this?

You can have some saturated in your diet, but aim to limit this fat to seven percent (preferably less) of your total daily calories.

Unsaturated Fats

• Heart healthy fat that when used in place of saturated fat has the potential to lower the bad cholesterol known as LDL.

• It is usually in a liquid form at room temperature and when chilled.

Why Unsaturated Fat is Good

• Unsaturated fat contains "essential" fatty acids needed by our bodies to make hormones and to ensure healthy cell structure.

• Contains omega-3 and omega-6 fatty acids, and is helpful to the heart, brain and other body systems.

Foods that have Unsaturated Fat

• Seafood

• Cooking oils such as vegetable, safflower, cottonseed and corn.

• Salmon, herring, and other fish

• Walnuts, sunflower seeds and flaxseeds.

Unsaturated fat is good, but…

• It still has calories.

• Aim for 10 percent of total daily calories

Trans Fat: the Ugly!

Who Loves Trans Fat?

• Bakeries, restaurants and food manufacturers use it.

• Can withstand repeated heating and cooking (especially deep-fried foods such as french fries, donuts, others), has a long shelf life in food (many types of baked or pre-packaged snacks) and lasts a long time before spoiling.

Where else can I find it?

• Beware of processed foods, fast foods and frozen foods

• Trans fats are also known as trans-fatty acids or may also be labeled as "partially hydrogenated vegetable oil" or vegetable shortening.

Why is trans fat so bad?

This type of fat is "man-made" by adding hydrogen to vegetable oil through a process known as "hydrogenation.“

The extra hydrogen atoms clog your heart and raise levels of cholesterol.

How much trans fat should I eat?

Your daily dietary intake of trans fat should be as close to zero as possible.

Here’s something to blow your (nutritional) mind:

Just like we need some fat, we also need some cholesterol!

WAIT…ISN’T IT TRUE THAT…

Too much cholesterol and the wrong type of cholesterol lead to dangers such as strokes and heart attacks.

What is cholesterol and why do we need it?

Cholesterol is a soft, fat-like substance that:

• Protects cell membranes

• Helps nerve cells send messages

• Building block for vitamin D

• Lets gallbladder make bile

• Base for estrogren or testosterone

Do any of these sound familiar?

• Cholesterol is carried through the bloodstream by attaching to certain proteins. The combination is called a lipoprotein. There are four different types of lipoproteins that carry cholesterol in the blood:

• High density lipoprotein (HDL) or "good cholesterol" • Low density lipoprotein (LDL) or "bad cholesterol" • Very low density lipoproteins (VLDL), which are very

bad forms of cholesterol. • Chylomicrons, which carry very little cholesterol, but

a lot of another fat called triglycerides.

Another reason trans fat is evil…

• Trans fat increases levels of bad cholesterol (LDL)

• It also destroys good cholesterol (HDL)

And now for something completely different