From all you hear, you'd think fat and calories are really
bad for you. It's true that many people are eating more fat and
calories than they need. But we all require a certain amount of fat
and calories in our diets to fuel our growth and activities -
everything from solving a math problem to racing up and down the
soccer field. So what's the truth on fat and calories?
What Are Fat and Calories?
Fats, or
lipids
, are nutrients in food that the body uses to build nerve tissue
(like the brain) and hormones. The body also uses fat as fuel. If
fats that a person has eaten aren't burned as energy or used as
building blocks, they are stored by the body in fat cells. This is
the body's way of thinking ahead: By saving fat for future use,
it plans for times when food might be scarce.
A calorie is a unit of energy that measures how much energy food
provides to the body. The body needs calories to function
properly.
Food Labels: Calories
Calories
Food labels list calories by the amount in each serving size.
Serving sizes differ from one food to the next, so to figure out
how many calories you're eating, you'll need to do three
things:
- Look at the serving size.
- See how many calories there are in one serving.
- Multiply the number of calories by the number of servings
you're going to eat.
For example, a bag of cookies may list three cookies as a
serving size. But if you eat six cookies, you are really eating two
servings, not one. To figure out how many calories those two
servings contain, you must double the calories in one serving.
When you start looking at food labels, you may be surprised at
some of the serving sizes. For example, on the labels of six cold
breakfast cereals, the serving size ranges from 1/2 cup (118
milliliters) to 13/4 cups (414 milliliters). You would have to more
than triple the smallest serving size (1/2 cup, or 118 milliliters)
to compare the calories in that cereal with the calories in the
cereal with the largest serving size (13/4 cups, or 414
milliliters). A small bag of corn chips may contain two or more
servings - although most people would eat the entire bag!
That's why it's always important to check the serving size
of all foods on the label.
Food Labels: Fat
Fat
When it comes to fat, labels can say many things. Low fat,
reduced fat, light (or lite), and fat free are common terms
you're sure to see on food packages. The U.S. government has
strict rules about the use of these phrases: By law, fat-free foods
can contain no more than 0.5 grams of fat per serving. Low-fat
foods may contain 3 grams of fat or less per serving. Foods marked
reduced fat and light (lite) are a little trickier, and you may
need to do some supermarket sleuthing.
Light (lite) and reduced-fat foods may still be high in fat. The
requirement for a food to be labeled light (lite) is that it must
contain 50% less fat or one third fewer calories per serving than
the regular version of that food. Foods labeled reduced fat must
contain 25% less fat per serving than the regular version. But if
the regular version of a particular food was high in fat to begin
with, a 25% to 50% reduction may not lower the fat content enough
to make it a smart snacking choice. For example, the original
version of a brand of peanut butter contains 17 grams of fat and
the reduced fat version contains 12 grams. That's still a lot
of fat!
It's important to figure out how many of the calories
you're getting come from fat. The 2005 U.S. dietary guidelines
recommend that children and teens ages 4-18 get between 25%
to 35% of their daily calories from fat. But food labels
don't always show the percentage of fat in a food. It is easy
to calculate, though. Divide the number of calories from fat by the
number of total calories and multiply by 100:
For example, if a 300-calorie food has 60 calories from fat, you
divide 60 by 300 and then multiply by 100. The result shows that
food gets 20% of its calories from fat:
4, 4, and . . . 9?
The calories in food come from carbohydrates, proteins, and
fats. A gram of carbohydrate contains 4 calories. A gram of protein
also contains 4 calories. A gram of fat, though, contains 9
calories - more than twice the amount of the other two.
That's why one food with the same serving size as another
may have far more calories. A high-fat food has many more calories
than a food that's low in fat and higher in protein or
carbohydrates.
For instance, a 1/2-cup (118-milliliter) serving of vanilla ice
cream contains:
- 178 total calories
- 2 grams of protein (2 grams times 4 calories = 8 calories
from protein)
- 12 grams of fat (12 grams times 9 calories = 108 calories, or
61%, from fat)
- 15.5 grams of carbohydrate (15.5 grams times 4 calories = 62
calories from carbohydrate)
Compare this with the same serving size (1/2 cup, 118
milliliters) of cooked carrots:
- 36 total calories
- 1 gram of protein (1 gram times 4 calories = 4 calories from
protein)
- 0 grams of fat (0 grams times 0 calories = 0 calories from
fat)
- 8 grams of carbohydrate (8 grams times 4 calories = 32
calories from carbohydrate)
So fat makes quite a difference when it comes to total calories
in a food.
But let's face it, who's going to choose a heaping bowl
of cooked carrots over ice cream on a hot summer day? It all comes
down to making sensible food choices most of the time. The goal is
to make tradeoffs that balance a higher-fat food with foods that
are lower in fat to keep the fat intake at 30% for the day. So if
you really want that ice cream, it's OK once in a while - as
long as you work in some lower-fat foods, like carrots, that
day.
Not All Fats Are the Same
Although all types of fat have the same amount of calories, some
are more harmful to your health than others. Two of the most
harmful fats are
saturated fat
and
trans fat
. Both of these fats can increase a person's risk of heart
disease. Food labels show the amounts of saturated fats and trans
fats in a particular food.
Saturated and trans fats are solid at room temperature - like
butter, shortening, or the fat on meat. Saturated fat comes mostly
from animal products, but some tropical oils, like palm kernel oil
and coconut oil, also contain saturated fat. Trans fat is also
found in whole dairy and meat products.
Trans fats are often found in packaged baked goods, like cookies
or crackers. They are also in fried foods like french fries and
doughnuts. Because saturated fat and trans fat raise blood
cholesterol levels, increasing a person's risk of developing
heart disease, a gram of one of these fats is worse for a
person's health than a gram of unsaturated fat.
Unsaturated fats
are liquid at room temperature. Unsaturated fats can be
polyunsaturated or monounsaturated.
Polyunsaturated fat
is found in soybean, corn, sesame and sunflower oils, or fish and
fish oil.
Monounsaturated fat
is found in olives, olive oil or canola oil, most nuts and their
oils, and avocados.
Fat and Calories in a Healthy Diet
Fats should be eaten in moderation. The American Heart
Association recommends that people get as much of their daily fat
intake as possible from unsaturated fats and that they limit
saturated fats and trans fats.
It's a bad idea to try to avoid fat completely, though,
especially for teens. A certain amount of fat is necessary for
development, especially during puberty when the body grows very
quickly.
Fats are also needed to absorb certain vitamins that are
essential for proper growth. Vitamins A, D, E, and K are
fat soluble
, meaning they can only be absorbed if there is fat in a
person's diet. Also, fat cells act as insulation to keep the
body warm and help protect the nerve cells.
Like fat, you need a certain amount of calories in your diet to
fuel your body. In fact, nutritionists do not recommend calorie
counting (keeping track of the number of calories in everything
that you eat) for teens unless a doctor has specifically
recommended it. So if you are concerned about your weight, speak to
your doctor.
Maintaining a healthy weight means choosing a variety
of foods that are low in fat (especially saturated and trans
fats) and added sugars. Think about substitutes for foods that have
a lot of sugar, fat, or calories. For example, you may want to
drink water or skim milk instead of soft drinks, or choose mustard
instead of mayonnaise on your sandwich.
Being aware of the amount of fat and calories you eat makes
sense, as long as you eat a balanced diet. Establishing sensible
eating habits, choosing foods wisely, and exercising regularly are
the keys to long-term good health.
Reviewed by:
Mary L. Gavin, MD
Date reviewed: October 2007
Originally reviewed by:
Jessica Donze Black, RD, CDE, MPH
Note: All information is for educational purposes only. For specific medical advice,
diagnoses, and treatment, consult your doctor.
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