"The New Calories Per Pound of Weight Loss Rule"
If the "3500 calories per pound" weight loss rule is bunk,
what's the alternative?
How many fewer calories do you have to eat,
or how many more do you have to burn, to lose a pound of fat?
There are validated mathematical models that take into account
the dynamic changes that occur when you cut calories,
such as the metabolic slowdown,
and they've been turned into free online calculators
that you can use to make personalized estimates.
There's the Body Weight Planner from the National Institutes of Health
and the Pennington Biomedical Research Center's Weight Loss Predictor
out of Louisiana State University.
Here are the two direct links.
Here are some shortened URLs (in parenthesis under each link)
The NIH Body Weight Planner has been found to be more accurate,
since the LSU model appears to overestimate the drop in
physical activity, but they both have their own pluses and minuses.
The Body Weight Planner tells you how many calories you need to restrict
and/or how much more exercise you need to do
to achieve a specific weight loss goal by a specific date.
If you click on the "Switch to Expert Mode" button you can get a graph,
and exportable chart showing your day-to-day weight loss trajectory.
So if you're a middle-aged, sedentary average height woman,
obese at 175 pounds, who wants to be closer to her ideal weight within a year,
2000 calories a day would prevent future weight gain,
about 1400 calories a day would bring your weight down like this,
and then you could maintain that lower weight at 1700 calories a day.
If, in addition, you walked a mile a day,
it would give you a little more calorie leeway.
The LSU Weight Loss Predictor, on the other hand,
doesn't allow you to tweak physical activity, but the advantage
is that you don't have to choose a goal or time frame.
Just put in different calorie changes and it graphs out your expected course.
Is there any easy rule of thumb you can use?
Yes. Every permanent 10-calorie drop in daily intake
will eventually lead to about one pound of weight loss,
though it takes about a year to achieve half the total weight change
and about three years to completely settle into the new weight.
So cutting 500 calories a day can cause the 50-pound weight loss
predicted by the 3500 Calorie Rule, but that's the total weight loss
at which you plateau, not an annual drop,
and it takes about three years to get there.
A 500-calorie deficit would be expected to cause about a 25-pound weight loss
the first year, and then an additional 25 over years two and three.
That's only if you can maintain the 500-calorie deficit, though.
If you're eating the same diet that led to the original weight problem,
but just in smaller servings, you should expect your appetite
to rev up about 45 calories per pound lost.
So if you were cutting 500 calories a day through portion control alone,
before you were down even a dozen pounds,
you'd feel so famished that you'd be driven to eat 500 calories more a day
and your weight loss could vanish.
That's why if you're dead-set on eating the same diet, the same foods
but just in smaller quantities, you have to cut down an additional 45 calories
per pound of desired weight loss to offset your hunger drive.
So to get that one pound off, instead of just 10 calories less per day,
using the 10 Calories Per Pound Rule, you'd have to eat 10 calories less
on top of the 45 less to account for the revving of your appetite, so 45 +10 = 55.
So just changing diet quantity and not quality,
it takes 55 calories less per day to lose a pound.
So that 500-calorie daily deficit would only net you
about a 9-pound weight loss over time instead of 50.
That's why portion control methods
can be such a frustrating failure for so many people.