Most fitness conscious people have heard 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, and so on. Right? Well, not so fast…
Dr. Kevin Hall, an investigator at the National Institute of Health in Bethesda 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 data in your own fat loss program:
Calculating the calories required to lose a pound and fine-tuning your caloric deficit
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"…
Note: The Burn the Fat, Feed The Muscle program not only has an entire chapter dedicated to helping you calculate your exact calorie needs, it was designed very specifically to keep a fairly conservative approach to caloric deficits and to maximize the amount of lean tissue you retain and minimize the amount of metabolic adaptation that occurs when you're dieting. The approach may be more conservative, and the fat loss may be slower, but it has a better long term track record… You can either lose weight fast, sacrifice muscle and gain the fat back like 95% of people do, or lose fat slow and keep it off forever like the 5% of the people who know the secrets. The choice is yours. For more information, visit:<<< Watch This Amazing Video For More Information >>>
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.
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