How many calories does a pound of muscle burn? I keep reading in HIT books that it burns 50-100 calories a day, but then I read stuff like this:
“In reality, one pound of muscle burns about seven to 15 calories a day, not 50, explains Dymphna Gallagher, the director of the body composition unit at the New York Obesity Research Center in Manhattan. So, if a person has managed to stick to a program lifting progressively heavier weights for a long enough stretch of time, they may accumulate enough extra muscle to boost their metabolism by about 14 to 30 calories a day — not several hundred, as is often claimed.”
I’m not sure what to believe, as HIT is based on empirical evidence I am curious as to how we reached higher numbers?
I believe the more conservative estimate of around 7 to 15 calories per day to maintain a pound of muscle is more accurate, however resistance training studies have shown a much greater increase in metabolic rate per pound of muscle gained (1, 2), which Dr. Wayne Westcott explains as resulting from an increase in protein turnover in all of the muscle mass trained (3, 4). If you are training hard on a regular basis you’re not just adding muscle, you are increasing the protein turnover in all of the muscle being worked which would have an increased metabolic cost beyond the energy demands of the workout. This is where you get numbers like 50, although I believe 50 may still be a bit on the high side.
Like most things, the actual increase in metabolic rate would depend on numerous individual factors. For example, if training increases the calories burned per pound of muscle someone starting out with more is going to have a greater increase in metabolic rate than someone starting with less even if they gain the same amount. In my opinion a more realistic range taking into account both additional muscle mass and increased protein turnover is around an additional 25 to 35 calories per day per pound.
Even by more conservative estimates strength training is still preferable to endurance activities or so-called “cardio” for fat loss for numerous reasons.
If we only look at the increase in metabolic rate due to increased protein turnover, which Westcott estimates at 1.5 calories per pound of muscle, a small woman with only 50 pounds of muscle who starts strength training is going to burn an additional 75 calories per day, even on days she doesn’t work out, and in addition to the calories she burns when she does. This would require as little as one or two half-hour workouts per week.
If she gains as little as 3 pounds of muscle — typical for women during their first two months of high intensity training — that number increases by 25.5 (7 to maintain and 1.5 due to protein turnover for each pound gained), for a total increase in daily calorie expenditure of 100, plus about 100 calories per workout, for a total of 800 to 900 additional calories per week.
This is comparable to what she would expect to burn if she ran or cycled with a high level of effort for 30 to 40 minutes every day. If this sounds low consider treadmills, cycles, elliptical machines and similar hamster wheels typically display the total calories burned during the activity, rather than the calories burned by the activity minus resting energy expenditure. Walking barely burns enough additional calories to even mention.
Even with a conservative estimate, 30 to 60 minutes of high intensity strength training per week results in an increase in calorie expenditure comparable to 210 to 280 minutes of endurance activities. Over a year the difference would be of over 160 hours — a full week — and this doesn’t even include travel time to and from the gym. Also, the 30 to 60 minute estimate for HIT workouts assumes workout out in a typical gym or fitness center during regular workout hours – during off-peak times or if you work out at home or in a private personal training studio it is possible to complete a full high intensity workout in half that time.
The following are photos of a girl I trained who lost 128 pounds over a period of 14 months, dropping from 245 to 117, with less than one hour of high intensity training per week and diet. That’s less than 60 hours total training time.
Preventing Muscle Loss
High intensity strength training is preferable to endurance activities for fat loss for several other reasons. Unlike endurance activities which can cause muscle loss and reduce metabolic rate if overdone or done in combination with prolonged calorie restriction, strength training will maintain or increase muscle mass even if calorie intake is restricted. This is the most important reason to exercise while trying to lose fat — not to burn calories, but to prevent the loss of lean body mass.
If a woman loses only three pounds of muscle as a result of excessive endurance activities she’ll burn 21 fewer calories per day, or about 147 fewer calories per week. Even if strength training didn’t increase metabolic rate, it would be worth doing to prevent the muscle loss and associated reduction in metabolic rate that can occur during extended periods of calorie restriction or as a result of chronic endurance activity.
In addition to the effect on metabolic rate muscle is important because the more you have the more carbohydrate your body can store as glycogen in the muscles rather than as triglycerides in fat (5).
This becomes even more important with age. Without proper strength training the average person loses about half a pound of muscle per year starting in their mid 20’s. By the time they are in their 40’s they have about 10 pounds less muscle than they had in their prime. Whenever a middle aged or older woman tells me she isn’t interested in gaining muscle I ask if she has a better body now than she did in her 20’s. Most answer they had a better body in their 20’s. They change their mind about wanting more muscle when I tell them they had about 10 pounds more back then.
Endurance activities will do nothing to prevent this muscle loss and can even accelerate it if overdone. Only proper strength training can effectively maintain or increase muscle mass.
If a person exercises for cosmetic reasons their goal is to optimize body composition not to lose weight indiscriminately. If a person attempts to lose weight by performing endurance activities what little weight they lose as a result will be a mix of fat and muscle. They may weigh less, but their body composition will not have improved much and rather than having a leaner body they’ll just be a smaller fat person.
If they change their diet they may lose more weight but without strength training to prevent muscle loss the weight loss will still be indiscriminate and best they can hope for is to end up being “skinny fat” — smaller and thinner, but still soft and flabby instead of hard and lean.
With strength training muscle mass can be maintained or even increased while fat is lost, so instead of being just a smaller fat person or “skinny fat” you become leaner.
HIT versus HIIT
Some would argue that high intensity interval training, or HIIT — brief periods of high intensity steady state activity such as running or cycling alternated with brief periods of rest — would burn the same calories as traditional lower intensity, longer duration endurance activities and better compare with high intensity strength training, or HIT in terms of time efficiency. Although HIIT is time efficient it still does not provide the muscle building benefits of HIT nor is it as safe. To increase the intensity of the work intervals in HIIT it is necessary to attempt to move even more quickly, increasing the already high forces on the body. Intensity progression in HIT is accomplished by gradual resistance increases, but no matter how heavy the weight gets as long as the trainee attempts to move it in a controlled manner without any quick bouncing, yanking or jerking movements the risk of injury is minimal.
Combining Strength Training and Endurance Training
The popular recommendation to combine the two is misguided, based on the belief endurance training is necessary for cardiovascular conditioning and calorie expenditure and strength training doesn’t provide these benefits. Not only is high intensity strength training equal or superior to traditional endurance activities for cardiovascular and metabolic conditioning (6,7), but has been shown to produce better fat loss on it’s own. A comparison of fat loss research by Ellington Darden(8) showed strength training and diet alone resulted in greater fat loss and muscle gain than when combined with endurance training and my experience as a personal trainer over the past two decades has confirmed this.
1. Campbell, W., Crim, M., Young, V. and Evans, W. 1994. Increased energy requirements and changes in body compositionwith resistance training in older adults. American Journal ofClinical Nutrition, 60: 167-175.
2. Pratley, R., Nicklas, B., Rubin, M., Miller, J., Smith, A., Smith, M., Hurley, B., and Goldberg, A. 1994. Strength training increases resting metabolic rate and norepinephrine levels in healthy 50 to 65 year-old men. Journal of Applied Physiology, 76: 133-137.
3. Pikosky, M., Faigenbaum, A., Westcott, W., and Rodriguez, N. 2002. Effects of resistance training on protein utilization in healthy children. Medicine and Science in Sports and Exercise, 34 (5): 820-827.
4. “Why the Confusion on Muscle and Metabolism?,” Wayne Westcott, PhD. http://www.sdsm.k12.wi.us/cms_files/resources/Why_The_Confusion.pdf
6. Maisch B, Baum E, Grimm W. Die Auswirkungen dynamischen Krafttrainings nach dem Nautilus-Prinzip auf kardiozirkulatorische Parameter und Ausdauerleistungsfähigkeit (The effects of resistance training according to the Nautilus principles on cardiocirculatory parameters and endurance). Angenommen vom Fachbereich Humanmedizin der Philipps-Universität Marburg am 11. Dezember 2003
7. James Peterson, PhD., Total Conditioning: A Case Study, Athletic Journal Vol. 56 September, 1975 http://baye.com/wp-content/uploads/2008/06/totalconditioning.pdf
8. Ellington Darden, PhD., Living Longer Stronger (Perigree, 1995), 125.