The simple answer: It depends on what you’re trying to do.

If you walk into most gyms today, you’ll typically see a major contrast between the weights being used by men and women. Women typically lift lighter weights, while men traditionally lift heavier weights. As women, we’ve been conditioned to believe that heavy weights are for men and that if we lift them we’ll get too ‘bulky’. 

Some women will curl 5 pound dumbbells for 25 reps in an effort to “tone” their arms, while some guys will bench a ton of weight for only a few reps in an effort to put on muscle and increase strength.

The idea behind this is that high reps help you lose fat and make muscle more “toned”. On the other hand, low reps can help you build muscle and increase strength.

But is it really this simple? High reps for fat loss and low reps for strength and muscle building? Let’s take a look at this a little more in depth…

High Reps vs. Low Reps

Low repetitions with heavy weight increases strength, whereas high repetitions with light weight increases endurance. According to this concept, as repetitions increase there is a gradual transition from strength to endurance.

For optimal strength increases, the research conclusively supports low reps with heavy weight vs. high reps with light weight, but high reps can still elicit gains in strength as well. I recently switched to the former and have seen great results in terms of muscle gain. I now combine the two principles and lift heavy weights with higher reps. Not easy, but very rewarding.

High Reps vs. Low Reps For Fat Loss

Some believe heavy weights are only good for building muscle, but what about fat loss? Can lifting heavier help you burn more fat or contribute to ‘bulkiness?’

One study from the University of Alabama in Birmingham showed that dieters who lifted heavy weights lost the same amount of weight as dieters who did just cardio, but all the weight lost by the weight lifters was fat while the cardio group lost muscle along with some fat. The common belief is that high reps magically gets rid of fat. While high reps with light weight to fatigue can create a muscular response, it does not necessarily remove fat better than low reps with heavy weight.

While more studies are needed to compare the fat loss effects of high reps vs. low reps, substantial evidence is mounting that it’s not necessarily the amount of weight that is used, or the number of repetitions that helps burn the most fat, but the intensity of the workout. The goal is to create muscular failure with less rest between exercises, which can have powerful hormonal, metabolic, and calorie burn effects. In addition, for fat loss, proper nutrition will have a MUCH greater impact on fat loss than the specific rep range, or even workout.

High Reps vs. Low Reps For Building Muscle

Similar to fat loss, the number of rep ranges that is optimal for muscle building is open to debate and the research is inconclusive. Most research points to reps under 15 reps as being better for muscle building, but other research shows muscle building can be equally effective with light weight and high reps.

There is a common misconception that lifting heavier weights automatically helps you build muscle. That’s not the case at all. In fact, how much you eat in combination with the overall volume and intensity of the workout and how it becomes more challenging over time will make the difference, not necessarily the weight/reps.

So what’s the verdict??? Whatever your fitness goal is, achieving balance is the most important factor. Strive to hit multiple rep ranges (i.e. low, medium, high) throughout the course of your training regimen and you will reap the results that you desire.