Can You Really Lose Fat While Gaining Muscle?

You won’t find a more commonly asked question than, “Can You Lose Fat And Gain Muscle At The Same Time?” And, as an answer you’ll get lots of different opinions. The fact is, this issue, along with other issues like it, isn’t about what this or that so-called “expert” says, and it’s definitely not about what some dude at gym says, as we know the saying about “opinions” – it’s about what the scientific evidence says.  And, there are several studies showing that yes, you can simultaneously build muscle and lose fat.

The Science

A 1997 study published in Medicine and Science in Sports and Exercise investigating the effects of strength training and aerobic exercise on body composition in a group of overweight, sedentary adult males. The men were randomly assigned to two groups: a cardio-only group, and a cross-training group that performed both cardiovascular and resistance exercise.  Each group trained three days per week for 14 weeks. At the conclusion of the study, the group that combined cardiovascular with resistance exercise was indeed able to lose fat (16.3 pounds) while simultaneously gaining muscle (9.5 pounds). (1)

Another 2007 study published in The American Journal of Clinical Nutrition showed that showed that older men and women (36 in total with an average age of 61), who did strength training three times per week for 12 weeks, gained an average of 4 pounds of muscle mass and lost over 4 pounds of fat. (2)

By now you’re surely saying to yourself, “sure these two above studies demonstrate that both sedentary and older individuals can lose fat and gain muscle at the same time, but what about for younger, active individuals?” Well, the answer to that question is: Yes! There’s also evidence showing that younger, active individuals can also lose fat and gain muscle at the same time!

A 1998 study published in the Journal of Applied Physiology took thirty physically active healthy men (average age of 20 and an average body fat of 12%) and randomly assigned to one of the following training groups: a cardio only group, a resistance training only group, and a combined cardio and resistance training group. All groups trained three times per week (3). At the conclusion of the study, the cardio group lost around 4 pounds of fat and they also lost a small amount of muscle, whereas the resistance training only group gained around 5 pounds of muscle while also losing almost 2 pounds of fat. And, the combined (cardio + resistance) training group got the best results: They gained 7 pounds of muscle while losing almost 6 pounds of fat.

Additionally, these results aren’t just in younger men, as a 2010 study published in Medicine and Science in Sports and Exercise found that young women (average age of 23) were able to gain 4.2 pounds of muscle and lose 3.5 pounds after 12-weeks of resistance exercise. (4)

In short, based on the scientific evidence, not on arbitrary opinions, both men and women, younger and older, active and sedentary can absolutely build muscle and lose fat at the same time.

Mike O’Hearn Knows How To Get Lean

A Word on Nutrition

It’s well established that fat loss is determined by burning more calories each day than you consume. The concept that you need to be in a caloric deficit in order to lose fat isn’t personal opinion nor is it up for debate by so-called diet gurus. This is the first law of thermodynamics, which states that energy can be neither created nor destroyed (conservation of energy), only changed from one form to another. Now don’t get it twisted, as this isn’t to discount that some calories are more nutrient dense than others. We’ve all heard the term empty calories before, but one can still be well nourished and over-fed. So as important as it is to eat high quality, nutrient-dense foods, one can still gain fat from eating “healthy,” if they eat too many calories relative to what they’re burning.

With that said, it’s worth mentioning that just as a caloric deficit is needed to lose fat, a caloric surplus is needed to build muscle. So, it stands to reason that one can’t build muscle while losing fat, which has led some people to hold this (false) notion. However, keep in mind that stored fat is stored energy, so those stored fat calories are available for the body to use as fuel for the muscle building process. No! Your body can’t turn fat into muscle or vice versa. Fat is fat and muscle is muscle. But, if you’re overweight, it can use your stored energy (i.e., stored fat is the caloric surplus) to fuel the muscle building process when that fuel isn’t coming from additional food intake. This is still consistent with the first law of thermodynamics, as the research shared above clearly demonstrated.

The above science also tells us that the more fat and less muscle one has, the greater one’s ability to gain muscle and lose fat at the same time. This is important to note, because if you’re already fairly lean, a large caloric deficit will generally make you lose some muscle even with strength training and adequate protein (5,6).  So, the goal, for everyone, especially when you’re not overweight but just looking to lose that extra bit of fat, is to make sure your diet delivers plenty of protein and that you’re emphasizing regular strength training as I’ve directed you in my book Strength Training for Fat Loss.


1. Wallace MB, et al. Effects of cross-training on markers of insulin resistance/hyperinsulinemia. Med Sci Sports Exerc. 1997 Sep;29(9):1170-5.

2. Iglay HB, et al. Resistance training and dietary protein: effects on glucose tolerance and contents of skeletal muscle insulin signaling proteins in older persons. Am J Clin Nutr. 2007 Apr;85(4):1005-13.

3. Dolezal BA. Et al. Concurrent resistance and endurance training influence basal metabolic rate in nondieting individuals. J Appl Physiol (1985). 1998 Aug;85(2):695-700.

4. Josse AR, et al. Body composition and strength changes in women with milk and resistance exercise. Med Sci Sports Exerc. 2010 Jun;42(6):1122-30.

5. Van der Ploeg GE, Brooks AG, Withers RT, Dollman J, Leaney F, Chatterton BE. Body composition changes in female bodybuilders during preparation for competition. Eur J Clin Nutr. 2001;55(4):268– 277.

6. Withers RT, Noell CJ, Whittingham NO, Chatterton BE, Schultz CG, Keeves JP. Body composition changes in elite male bodybuilders during preparation for competition. Aust J Sci Med Sport. 1997;29(1):11–16.


Strength Training for Fat Loss by Nick Tumminello

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