Most fitness conscious people know that there are 3,500
calories in a pound of fat, so if you create a deficit of
3500 calories in a week, you lose a pound of weight. If you
create a deficit of 7000 calories in a week, you lose two
pounds a week, and so on. Right? Well, not so fast...
Dr. Kevin Hall, an investigator at the National Institute
of Health has done some interesting research about the
mechanisms regulating human body weight. He recently
published a new paper in the International Journal of
Obesity that throws a wrench in works of the "3500 calories
to lose a pound" idea...
Some of the equations in his paper made my head hurt, but
despite the complex math he used to come to his
conclusions, his article clearly prompts the question,
"3500 calories to lose a pound of WHAT?" His paper also
contained a lot of simple and practical tips you can use to
properly balance your caloric intake with output, fine tune
your calorie deficit and help you retain more muscle when
you diet.
Below, I've distilled some of the information into a simple
bullet-point summary that any non-scientist can understand.
Then I wrap up with my interpretation of how you can apply
this in your own fat loss program:
Calculating the calories required to lose a pound and
fine-tuning your caloric deficit
* 3500 calories to lose a pound has always been the rule of
thumb. However, this 3500 calories figure goes back to
research which assumed that all the weight lost would be
adipose tissue (which would be ideal, of course).
* But as we all know (unfortunately), lean body mass is
lost along with body fat, which would indicate that the
3500 calorie figure could be an oversimplification.
* The amount of lean body mass lost is based on initial
body fat level and size of the calorie deficit
* Lean people tend to lose more lean body mass and retain
more fat.
* Fat people tend to lose more body fat and retain more
lean tissue (revealing why obese people can tolerate
aggressive low calorie diets better than already lean
people)
* Very aggressive low calorie diets tend to erode lean body
mass to a greater degree than more conservative diets.
* whether the weight loss is lean or fat gives you the real
answer of what is the required energy deficit per unit of
weight loss
* The metabolizable energy in fat is different than the
metabolizable energy in muscle tissue. A pound of muscle is
not 3500 calories. A pound of muscle yields about 600
calories. • If you lose lean body mass, then you lose more
weight than if you lose fat.
* If you create a 3500 calorie deficit in one week and you
lose 100% body fat, you will lose one pound. •
* But if you create a 3500 calorie weekly deficit and as a
result of that deficit, lose 100% muscle, you would lose
almost 6 pounds of body weight! (of course, if you manage
to lose 100% muscle, you will be forced to wear the
Dieter's Dunce cap)
* If you have a high initial body fat percentage, then you
are going to lose more fat relative to lean, so you may
need a larger deficit to lose the same amount of weight as
compared to a lean person
* Creating a calorie deficit once at the beginning of a
diet and maintaining that same caloric intake for the
duration of the diet after major weight loss fails to
account for how your body decreases energy expenditure with
reduced body weight
* Weight loss typically slows down over time for a
prescribed constant diet (the "plateau"). This is either
due to the decreased metabolism mentioned above, or a
relaxing of the diet compliance, or both (most people just
can't hack aggressive calorie reductions for long)
* Progressive resistance training and or high protein diets
can modify the proportion of weight lost from body fat
versus lean tissue (which is why weight training and
sufficient protein while on calorie restricted diets are
absolute musts!)
So, based on this info, should you throw out the old
calorie formulas?
Well, not necessarily. You can still use the standard
calorie formulas to figure out how much you should eat, and
you can use a 500-1000 calorie per day deficit (below
maintenance) as a generic guideline to figure where to set
your calories to lose one or two pounds per week
respectively (at least that works "on paper" anyway).
Even better however, you could use this info to fine tune
your caloric deficit using a percentage method and also
base your deficit on your starting body fat level, to get a
much more personalized and effective approach:
15-20% below maintenance calories = conservative deficit
20-25% below maintenance calories = moderate deficit
25-30% below maintenance calories = aggressive deficit
31-40% below maintenance calories = very aggressive deficit
(risky)
50%+ below maintenance calories = semi
starvation/starvation (potentially dangerous and unhealthy)
(Note: According to exercise physiologists Katch & Mcardle,
the average female between the ages of 23 and 50 has a
maintenance level of about 2000-2100 calories per day and
the average male about 2700-2900 calories per day)
Usually, we would suggest starting with a conservative
deficit of around 15-20% below maintenance. Based on this
research, however, we see that there can be a big
difference between lean and overweight people in how many
calories they can or should cut.
If you have very high body fat to begin with, the typical
rule of thumb on calorie deficits may underestimate the
deficit required to lose a pound. It may also be too
conservative, and you can probably use a more aggressive
deficit safely without as much worry about muscle loss or
metabolic slowdown.
If you are extremely lean, like a bodybuilder trying to get
ready for competition, you would want to be very cautious
about using aggressive calorie deficits. You'd be better
off keeping the deficit conservative and starting your
diet/cutting phase earlier to allow for a slow, but safe
rate of fat loss, with maximum retention of muscle tissue.
The bottom line is that it's not quite so simple as 3,500
calories being the deficit to lose a pound. Like lots of
other things in nutrition that vary from person to person,
the ideal amount of calories to cut "depends"...
References:
Forbes GB. Body fat content influences the body composition
response to nutrition and exercise. Ann NY Acad Sci. 904:
359-365. 2000
Hall, KD., What is the required energy deficit per unit of
weight loss? Int J Obesity. 2007 Epub ahead of print.
McArdle WD. Exercise physiology: Energy, Nutrition, and
Human performance. 4td ed. Williams & Wilkins. 1996.
Wishnofsky M. Caloric equivalents of gained or lost weight.
Am J Clin Nutr. 6: 542-546.
----------------------------------------------------
Tom Venuto is a lifetime natural bodybuilder, an
NSCA-certified personal trainer, certified strength &
conditioning specialist (CSCS), and author of the #1 best
selling diet e-book, Burn The Fat, Feed The Muscle. Tom
teaches you how to lose fat without drugs or supplements
using the little-known secrets of the world's best
bodybuilders and fitness models. Learn how to get rid of
stubborn fat and turbo-charge your metabolism by visiting
http://www.BurnTheFat.com , home of Burn The Fat, Feed The
Muscle and http://www.BurnTheFatInnerCircle.Com , the
Internet's premier members-only fat loss support community.
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