September 28th, 2007
3500 Calories To Lose A Pound… Is This Formula All Wrong?
Fat loss is all about energy balance. Almost everybody has heard that there’s 3,500 calories in a pound of fat, so if you create a negative energy balance of 3500 calories in a week, you lose a pound of weight. Create a negative energy balance of 7000 calories (deficit) in a week and you tip the scale to a two pound weight loss and so on, right?Not so fast…Dr. Kevin Hall, an investigator at the National Institute of Healthin Bethesda has done some interesting research aboutthe mechanisms regulating human body weight.He recently published a new paper in the International Journal ofObesity that throws a wrench in works of the “3500 calories to lose a pound” idea…
Some of the equations in his paper gave me a headache… but despitethe complex formulas he used to come to his conclusions, the article contained a lot of simple and very 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, and then I wrap up with my interpretation of how you can apply this:
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 whichassumed 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 alongwith body fat, which would indicate that the 3500 calorie figure could bean oversimplification.
- The amount of lean body mass lost is based on initial body fatlevel and size of the calrie 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 extremely low caloriediets better than already lean people)
- Very aggressive low calorie diets tend to erode lean body mass to a greater degreethan more conservative diets.
- whether the weight loss is lean or fat gives you the realanswer of what is the required energy deficit per unit of weight loss
- The metabolizable energy in fat is different than the metabolizableeneregy 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 thanif you lose fat.
- If you create a 3500 calorie deficit in one week and youlose 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 mangage to lose 100% muscle, you will be forced to wear theDieter’s Dunce cap)
- If you have a high initial body fat percentage, then you are goingto lose more fat relative to lean, so you will need a larger deficitto lose the same amount of weight as compared to a lean person!
- Creating a calorie deficit once at the beginning of a diet andmaintaining that same caloric intake for the duration of the dietand after major weight loss fails to account for how your body decreases energyexpenditure with reduced body weight
- Weight loss typically slows down over time for a prescribed constantdiet (the “plateau”). This is either due to the decreased metabolism mentioned above, or a relaxing of thediet compliance, or both (most people just can’t hack aggressivecalorie reductions for long)
- Progressive resistance training and or high protein diets can modifythe proportion of weight lost from body fat vs 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 formulasto figure out how much you should eat, and you can use a 500-1000 calorieper day deficit (below maintenance) as a generic guideline to figure where to set your caloriesto lose one or two pounds per week respectively (at least 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. What Dr. Hall’s research is saying, is that there can be big differences 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 also probably use a moderate to aggressive deficit more safely without as much worry about muscle loss, metabolic slowdown, etc.
If you are extremely lean, like a bodybuilder trying to geteven leaner for competition, you would want to be very cautious using aggressive calorie deficits.You’d be better off keeping the deficit conservative and startingyour diet/cutting phase earlier to allow for a slow, but safe rateof fat loss, with maximum retention of muscle tissue.
The long and short of it is that its not quite so simple as 3,500calories being the deficit to lose a pound. Like lots of other thingsin nutrition that vary from person to person, the ideal amount of calories to cut “depends”…
Sincerely,
Your friend and coach
Tom Venuto, CSCS, NSCA-CPT
www.BurnTheFat.com
www.BurnTheFatInnerCircle.com
PS. The Burn the Fat program not only has an entire chapter dedicated to helping you calculate your exact calorie needs, it was designed very specificallyto keep a fairly conservative approach to caloric deficitsand to maximize the amount of lean tissue you retain andminimize the amount of metabolic adaptation that occurs whenyou’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 keepit off forever like the 5% of the people who know the secrets. The choice is yours:
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:: THE BIBLE OF FAT LOSS ::
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BURN THE FAT, FEED THE MUSCLE
How to burn body fat and keep it off for lifewithout supplements, pills or starvation dieting:
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Hi Tom,
I just finished my second month on your program, and the results,I tell you, are amazing.
I have booked a seminar for this saturday with a local IFFB champion,for figure competition posing and presentation work. I have set to domy first figure competition the 1 st of december as my goal.
I have already lost 12 lb of fat, gained over 6 lb of lean mass and morethan 11% of body fat. I think the results are amazing, I wear a size 8now (I was more than 12 ) actually dressing pants might be a 6 now .My working pants are falling off me and people is looking at me with adifferent attitude ( i feel like I own the world, I really do )
I have felt so many emotional changes and sometimes I felt overwelmedand almost cried, just because I was so happy, so proud for the firsttime in long time , I am following thru.
I will send you some pics later on, form the start to the end, possiblyme holding at least my class trophy! ( masters over 35 ).
Thank you so much Tom, sorry the long letter, I dont have many people toshare what I went thru, but I know you understand.
Sincerely,
Vanessa D
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Article 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.
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