Content of Foods:
A Scientific Breakthrough
A typical calorie chart shows the calorie content of foods by
portion sizes, like a cup of rice or a large apple. For effective
weight loss, we actually want to select foods with a low
density. What is calorie density? It is a way of finding good weight
by checking how may calories they contain per ounce (or per
pound or per 100 grams.)
Much of the research on calorie density was
done at by Barbara Rolls, Ph.D.
She and a team of researchers have
dozens of studies on eating behavior.
They did their research at the Laboratory for the Study of
Human Ingestive Behavior at Penn State.
Calories by weight of food
These researchers studied the foods people ate and they
learned something interesting:
person eats about the same weight of food every
day. This is true even though the calorie content of
foods changes every day. There is something about the weight
of food that
fills our stomach and triggers feelings of satiety in our
But the calories in an ounce of one food can be
very different from the calories in an ounce of a different food. The number of calories per
ounce of a food is called the calorie density.
An ounce of celery contains 4.5 calories and an ounce of peanut butter
has 166.7 calories. The
calorie density of celery is 4.5
and the calorie density
of peanut butter is 166.7. Are they both low calorie foods?
Definitely not. The celery certainly is. Peanut butter might be
"low in calories" if you only eat one tenth of an ounce of it. But who
can do that? :-)
Scientists have done many studies to measure the
calorie density of peoples' diets. They measure it the same way they
measure the calorie density of a single food. They divide the calorie
content of foods someone eats in a day by the number of ounces
person eats. The studies all show the same thing:
Density of Diet:
Loss or Gain:
|Under 25 cal/oz
||All people lose weight, no matter how much
food they eat.
|25 - 37.5 cal/oz
||Most people lose weight.
|37.5 - 50 cal/oz
||If people get some moderate exercise, they
all lose weight.
|50 - 75 cal/oz
||Everyone gains weight, except for people
who get a lot of exercise.
|Over 75 cal/oz
||Everyone gains weight.
How calorie density works
eat one ounce of celery filled with one ounce of peanut butter. That
makes 2 ounces of food containing a total of 171.2 calories (4.5 +
166.7). Divide by 2 and we have a snack with 85.6 calories per ounce.
The calorie density is way too high and will contribute to weight gain.
Maybe we love peanut butter and we just have to
have some with our celery. Let's
say we get some exercise evey day and we want to keep our calorie
density between 30 and 35. An ounce of peanut butter and 5 oz of celery
would give us a calorie density of 31.5. That is a
number we could live with....for a snack.
Cancer and calorie density
The American Institute for Cancer Research (AICR) recently released a
report stating that overweight and obese people have a higher risk of
cancer than normal weight people. They recommended that
to avoid weight problems and cancer, we
should keep the calorie density of our diet around 34.5 - 37.5
Few people meet that requirement today. But in 1949 in
Okinawa, nearly everyone did. The
traditional Okinawan diet had a calorie density of 37.5 - 40.6
The Okinawans were slender and healthy. They didn't know the calorie
content of foods in their diet. Most of their calories
from sweet potatoes...they
ate a lot of them! Only 8
percent of their calories came from fat. A sweet potato diet with
some leafy greens, beans, and fruit would give us all the
nutrients we need. And it
would fill us up.
How to calculate calorie density
For packaged foods:
For fresh foods or a specific recipe, here are two options:
Look at the Nutrition Facts to find out how
many ounces are in one serving. If the servings are measured in grams,
divide the grams by 28.35 to get ounces. (Divide by 30 for a rough
estimate.) Note: this
only works if you are eating the food the way it comes
out of the package. If you have to add water or other
calorie density changes.
Divide calories by ounces.
But seriously, why bother to analyze fresh foods or recipes? You don't
need to know the exact calorie content of foods you eat. Just eat
mainly foods with a low calorie density: vegetables, fruits,
legumes, and intact whole grains. Limit the foods that have a
high calorie density, like nuts. You can use small portions to make
dressings or sauces.
Brown rice, beans, and salsa are all low calorie foods. This is a
weight loss meal as long as we don't add oil or