AnnW
04-24-2002, 12:05 PM
There are big differences in the way people's bodies handle calories.
By Kelly Brownell , Ph.D.
Question:
Do people's daily calorie requirements vary? For example, might two women the
same age and weight need different calorie amounts a day to maintain their
weight, because their bodies process calories differently?
Answer:
May 7, 2001 -- You are correct. There are big differences in the way people's
bodies handle calories. Believe it or not, it has only been in the past 15-20
years that experts on nutrition have acknowledged this, even though the
evidence is all around us. For instance, we all know some people who eat
normally and tend to gain weight, and others who eat a lot and stay thin. If we
look at two women of the same age, the same weight, and the same level of
physical activity, one woman might eat 1,200 calories per day to maintain her
weight and another might be able to eat 2,400. Usually the difference is less
than this, but the differences are real.
It is common for people to say that 3,500 calories equals a pound. If you cut
back your intake from its usual level and/or increase exercise, and there is a
500 calorie per day reduction, 3,500 calories would be the weekly reduction,
and a person would lose 1 pound per week.
With that said, these formulas do not fit everyone's experience. They are based
on crude estimates and cannot account for the differences among people in the
way their bodies manage calories. In addition, weight fluctuates due to water
changes in the body, the particular foods a person eats, and more.
The overall message is that it is not possible for you to get a precise formula
unless you do some expensive medical tests. If you keep track of your eating
and exercise, you'll find out yourself how much you can lose. WebMD has a
helpful means of keeping a record of eating and activity -- your personalized
Diet & Fitness Journal.
In the end, losing weight is a matter of creating a "negative energy balance."
When the number of calories a person takes in (through eating) is the same as
the energy expended (through activity and maintenance of bodily functions), a
person is in balance and weight stays stable. Negative energy balance occurs
when intake is less than expenditure. The body must then draw its energy from
reserves (fat) and weight loss occurs.
When people go on a diet to lose weight, they naturally think of ways to cut
back on their calorie intake. This is important, to be sure, but it is also
important to boost the amount of energy your body expends. The way to do this
is to increase physical activity. You might be surprised to learn that the
single best predictor of long-term weight loss is whether or not people
exercise regularly. The exercise helps not only because it burns calories, but
also because it builds muscle (which burns more calories than the fat it
replaces), boosts metabolism, and has other positive effects. And even if you
started exercising and never lost an ounce, the exercise itself could have
important health benefits.
The body is a fascinating calorie machine. Take good care of it and it will
take care of you.
Kelly D. Brownell, PhD, is an internationally known expert on eating disorders,
obesity, and body weight regulation. He is a professor of psychology at Yale
University, where he also serves as professor of epidemiology and public health
and as director of the Yale Center for Eating and Weight Disorders.
By Kelly Brownell , Ph.D.
Question:
Do people's daily calorie requirements vary? For example, might two women the
same age and weight need different calorie amounts a day to maintain their
weight, because their bodies process calories differently?
Answer:
May 7, 2001 -- You are correct. There are big differences in the way people's
bodies handle calories. Believe it or not, it has only been in the past 15-20
years that experts on nutrition have acknowledged this, even though the
evidence is all around us. For instance, we all know some people who eat
normally and tend to gain weight, and others who eat a lot and stay thin. If we
look at two women of the same age, the same weight, and the same level of
physical activity, one woman might eat 1,200 calories per day to maintain her
weight and another might be able to eat 2,400. Usually the difference is less
than this, but the differences are real.
It is common for people to say that 3,500 calories equals a pound. If you cut
back your intake from its usual level and/or increase exercise, and there is a
500 calorie per day reduction, 3,500 calories would be the weekly reduction,
and a person would lose 1 pound per week.
With that said, these formulas do not fit everyone's experience. They are based
on crude estimates and cannot account for the differences among people in the
way their bodies manage calories. In addition, weight fluctuates due to water
changes in the body, the particular foods a person eats, and more.
The overall message is that it is not possible for you to get a precise formula
unless you do some expensive medical tests. If you keep track of your eating
and exercise, you'll find out yourself how much you can lose. WebMD has a
helpful means of keeping a record of eating and activity -- your personalized
Diet & Fitness Journal.
In the end, losing weight is a matter of creating a "negative energy balance."
When the number of calories a person takes in (through eating) is the same as
the energy expended (through activity and maintenance of bodily functions), a
person is in balance and weight stays stable. Negative energy balance occurs
when intake is less than expenditure. The body must then draw its energy from
reserves (fat) and weight loss occurs.
When people go on a diet to lose weight, they naturally think of ways to cut
back on their calorie intake. This is important, to be sure, but it is also
important to boost the amount of energy your body expends. The way to do this
is to increase physical activity. You might be surprised to learn that the
single best predictor of long-term weight loss is whether or not people
exercise regularly. The exercise helps not only because it burns calories, but
also because it builds muscle (which burns more calories than the fat it
replaces), boosts metabolism, and has other positive effects. And even if you
started exercising and never lost an ounce, the exercise itself could have
important health benefits.
The body is a fascinating calorie machine. Take good care of it and it will
take care of you.
Kelly D. Brownell, PhD, is an internationally known expert on eating disorders,
obesity, and body weight regulation. He is a professor of psychology at Yale
University, where he also serves as professor of epidemiology and public health
and as director of the Yale Center for Eating and Weight Disorders.