Editor's Note:  I always get emails from guys wondering if it's possible to build muscle and lose fat at the same time. In an effort to answer this questions, I found this awesome article by Christian Finn that sums up the issue perfectly!

With very few exceptions, losing a lot of fat and gaining a lot of muscle at the same time is very hard to do. That's because of the opposing demands these goals impose on your body.

To build a lot of new muscle tissue, your body needs energy. In other words, you'll need to overfeed—to consume more calories than you're burning each day. To lose fat, you need to underfeed—to consume fewer calories than you burn.

If you do try to do both things at once, your progress in either direction will be so frustratingly slow that it won't be long before you feel like throwing in the towel.

It would be nice if the energy your body needs to build new muscle tissue came from stored fat. But, when your body is in a predominantly catabolic state (which it will need to be if you want to lose fat), gaining muscle is not its main priority.

Here are two studies that illustrate what I'm talking about. In the first trial, researchers from California State University tracked a group of healthy men for eight weeks [3]. The men consumed an average of 4,339 calories daily, and trained with weights four days each week for 60-90 minutes. On average, the men gained six pounds of muscle and one-half pound of fat.

In a second study, published in the journal Metabolism, researchers instructed a group of men to switch from their normal diet to a low-carbohydrate diet [2]. The men also trained with weights several times each week. Total fat loss at the end of the six-week study was just over seven pounds. The men also gained just over two pounds of muscle.

So, both groups lost fat and gained muscle. However, overfeeding led to far greater gains in muscle than underfeeding. And underfeeding led to a greater loss of fat than overfeeding.

Overfeeding
Calories per pound of bodyweight 25.7 calories (4,348)
Muscle mass + 6.4 pounds
Fat mass + 0.4 pounds

Underfeeding
Calories per pound of bodyweight 13.4 calories (2,334)
Muscle mass + 2.4 pounds
Fat mass - 7.3 pounds

The men who overfed gained an average of 0.8 pounds of muscle per week. The men who underfed gained an average of 0.4 pounds of muscle per week. In other words, the group who overfed gained muscle at twice the rate of the group who underfed.

The same holds true for women as well as men. A University of Michigan study of 40 overweight women shows that restricting calories means slower muscle growth [4].

The women who trained with weights for eight weeks but didn't diet added 2.4 pounds (1.1 kilograms) of muscle. The women who trained with weights and dieted put on less than one pound (0.4 kilograms) of muscle.

One exception to the rule is beginners. People who are just starting a weight-training program can gain a significant amount of muscle mass while losing fat.

For example, researchers from the United States Sports Academy tracked a group of previously sedentary men (i.e. beginners) who performed both endurance and resistance exercise three days per week for 14 weeks [5]

On average, the men lost 16.3 pounds of fat and gained 9.5 pounds of muscle. Even for beginners, this is an unusually large amount of muscle gain given the rate of fat loss.

However, when you look at the results of the study in detail, the numbers for lean mass do show a large standard error (an estimate of the amount of variation to be expected in a particular test).

So, it's possible that one or more of the men in the study was genetically predisposed to build muscle, while others might have made little or no progress.

Let's say that you take a group of six men and put them on a weight-training program for 12 weeks. Two of the men might make reasonable progress and gain five pounds of muscle. Another two might make very slow progress, and gain only two pounds.

If we average out this set of results, the average lean mass gain is 3.5 pounds.

But, if the other two guys have an easy time putting on muscle (let's say they gain 12 pounds of lean mass), they're going to skew the results of the group. They're called "outliers" because their results lie outside the normal range. Adding their results to those of the other four men bumps the average muscle gain up to 6.3 pounds, which isn't really an accurate reflection of the results of the group (remember that two-thirds of the men gained 3.5 pounds or less).

Although individual results for each subject aren't listed in the United States Sports Academy study, I'm guessing that the presence of a few outliers explains why the average muscle gain is so large.

So, what does all of this mean for you?

Rather than trying to build a lot of muscle and lose a lot of fat at the same time, you'll get better results by splitting your training goals into several phases, and working on one after the other. I suggest that you focus on one of two goals—building muscle while minimizing fat gain, or, losing fat while preserving muscle.

It's far more realistic to expect to lose 10 pounds of fat while gaining a pound or two of muscle, or to gain five pounds of muscle while adding a couple of pounds of fat. Losing 10 pounds of fat at the same time as replacing it with 10 pounds of muscle is the exception and not the rule.

There are several different methods you can use to decide how long to spend on each goal. One approach is to track your body fat percentage. Let's say that you start out at 10% body fat. In this case, you might decide to bulk up until you reach 12%. Then, you switch gears and enter the fat-loss phase of your program until you're back to 10% again.

Editor's Note: To learn more about body fat percentage and how to accurately measure it, I recommend you read the article titled, What is Your Body Fat Percentage?

If fat loss is a priority, you can take the opposite approach and start by losing fat until you're down to 7-8% body fat. Then, you change focus and start gaining weight until you're back to 10% again.

Aim for a diet providing 20-25 calories per pound of bodyweight during the overfeeding phase. You'll be able to lose fat during the underfeeding phase with 9-13 calories per pound of bodyweight (members of my website, www.TheFactsAboutFitness.com, have access to more information about what and when to eat so that they can build muscle without getting fat or lose fat without losing muscle).

This type of eating produces a "saw tooth" pattern of weight gain and weight loss, with the end result (hopefully) that you'll end up with more muscle and less fat after several cycles.

The big problem with this approach is that most methods available to track body fat levels are notoriously unreliable. I prefer to use more subjective (but, in my opinion, more useful) ways to gauge my progress.

For instance, I know that it's time to start losing fat when my lower abs become hidden under a layer of fat and I can't see them clearly. Conversely, when I start to feel irritable, tired and de-motivated on a regular basis (which usually happens after an extended period of dieting), and I'm happy with the way I look in the mirror, then I decide to focus on gaining weight and building muscle.

If I need any extra help overcoming my natural tendency towards gluttony and sloth, I'll book a session with a photographer to coincide with the end of a fat-loss phase.

If you live in the UK, I recommend paying a visit to Stu Williamson (www.StuWilliamson.com), who took the most recent set of photographs I had done. The studio is right next to the train station at Market Harborough, which is on the direct line from London. This means you can get on a train at St. Pancras station and arrive at the studio in around one hour without the hassle and stress of changing trains, organizing a taxi or getting stuck in a traffic jam on the M1 for three hours.

Knowing that I'll look like a complete fool if I show up for a photo shoot fat and out-of-shape gives me the extra motivation I need to drag myself out of bed and to the gym when I really don't feel like it. Maybe a little extra pressure to get in shape will help you too.
 

Read other articles by Christian Finn

About the Author

Christian Finn is a Certified Personal Trainer and holds a masters degree with distinction in exercise science. He's lectured at a number of universities and private training organizations around the United Kingdom on fitness training, weight loss and the effective use of nutritional supplements. He writes extensively on the subject and his articles have been published in numerous magazines, leading industry journals and websites worldwide, including Men's Health, Men's Health Muscle, Fit Pro (April/May 2001), CAM magazine (February 2003), Image (January 1997), Zest (March 2004), and Body Life magazine (March/April 1997). He was also featured in the July 2004 issue of Muscle & Fitness (UK edition). His website, TheFactsAboutFitness.com, is dedicated to providing its members up-to-date, unbiased information and research on the world of fitness.

References

1. Forbes, G.B. (2000). Body fat content influences the body composition response to nutrition and exercise. Annals of the New York Academy of Sciences, 904, 359-365

2. Volek, J.S., Sharman, M.J., Love, D.M., Avery, N.G., Gomez, A.L., Scheett, T.P., & Kraemer, W.J. (2002). Body composition and hormonal responses to a carbohydrate-restricted diet. Metabolism, 51, 864-870

3. Rozenek, R., Ward, P., Long, S., & Garhammer, J. (2002). Effects of high-calorie supplements on body composition and muscular strength following resistance training. Journal of Sports Medicine and Physical Fitness, 42, 340-347

4. Ballor, D.L., Katch, V.L., Becque, M.D., & Marks, C.R. (1988). Resistance weight training during caloric restriction enhances lean body weight maintenance. American Journal of Clinical Nutrition, 47, 19-25

5. Wallace, M.B., Mills, B.D., & Browning, C.L. (1997). Effects of cross training on markers of insulin resistance/hyperinsulinemia. Medicine and Science in Sports and Exercise, 29, 1170-1175