Weight Training Intensity – How Many Reps To Build Muscle And Lose Fat

Do you need to do many reps to build muscle or gain strength? And what about fat loss? Are there any rep ranges that will give you the best result? And what does intensity have to do with reps per set? I will try to answer these question in today’s post.

I mentioned it before but I think it’s worth repeating – there are three cornerstones of weight training program design – frequency, volume and intensity. Frequency is about how often you train in general, or how often you train each muscle (muscle group). Volume is about how many sets x reps, or just how many hard sets you do. As you’ve probably guessed, today we will look at the last one – weight training intensity. Let’s start with some theory first and finish with some recommendations.

man struggling while performing a squat

What Is Weight Training Intensity

What is intensity in relation to weight training? It can be defined in two ways, as an intensity of load and as an intensity of effort. An intensity of load is simply the weight you’re lifting, for example the percentage of your 1RM ( the maximum weight you’re able to lift only once). The intensity of effort is how hard it is for you to lift a certain weight.

I think an example will illustrate it the best. Let say we have two buddies, Jack and John, that train together. Both are able to squat 200 lbs for 1 rep and they decide to test their 8RMs:

– Jack was able to squat 160 lbs (80%) for 8 reps max

– John was able to squat 140 lbs (70%) for 8 reps max

If you look at the numbers, Jack has a higher intensity of load compared to Jack, but the intensity of effort is the same for both because both of them were able to do a maximum of 8 reps max with the given weight.

So the intensity is simply the weight you’ll be lifting and how easy or hard it is for you to lift that weight. If you find the weight easy to train with -> it’s low intensity. And vice versa, if you find the weight hard to lift -> it’s high intensity.

This, of course, affects how many repetitions (reps for short) you’ll be able to do on a given exercise. If you use light weight (low intensity) you’ll be able to do many reps. If you use heavy weight (high intensity) you’ll be able to do fewer reps, which leads to the question…

How Heavy Should You Train?

This is very important question because it will dictate how many reps per set you’ll be able to do. We could change the question to: How Many Reps Should You Do? The answer is that it depends on your goal:

– if your main goal is to improve maximal strength – you should train between 1 to 6 reps per set

– if your main goal is to build muscle as fast as possible – you should train between 6 to 15, up to 20 reps per set

– if your main goal is to improve muscle endurance – you should train using more than 20 reps per set

The VERY important point to mention here is that you should perform these sets to the point where you are 1 – 2 reps from failure. What does it mean? Imagine you’re training bench press for strength, so you decided to do sets of 5 reps. You load the bar, do 5 reps and you feel like you could do another 5. This indicates that the weight you’ve used was too light. On the other hand, if you’ve barely managed to do 5 reps out of which the last rep was a max effort with an ugly form – the weight was too heavy.

dumbbells in the rack

Another important point to mention here is that you will gain strength and build muscle using all rep ranges but the strength gains will be specific to the rep range you’re using the most. If you train mostly in the very popular 8 – 12 reps range, you will be strongest in this range but you maximal strength won’t be as high as if you’ve trained specifically for this purpose (principle of specificity).

The best approach here is to use two or three rep ranges in your training, whatever is your goal. But don’t go overboard and do most of your training in the rep range that is most useful for your goal. I will try to illustrate the reason for this with an example:

Let’s say that your main goal is to build muscle as fast as possible. To do that you should be training mostly in the rep range between 6 to 20 reps. Let’s say you’ve spent 8 to 10 weeks using this rep range and your body is used to it so it doesn’t cause the same adaptation as at the beginning. What you should do now is to introduce a different stimulus like increase the intensity (and lower the reps) and train mainly for strength for a few weeks (3-4). This will “reset” your muscles so they will be more sensitive to higher volume training and ready for another muscle building phase.

What If My Goal Is To Lose Fat?

If you goal is to lose fat (and I assume you also want to minimize the muscle loss) you don’t need to change almost anything compared to gaining muscle/strength. This goes probably against advice that you’ve read or heard, but think about this:

When you’re training for muscle/strength gain you have to train in a way that gives your muscle the best stimulation to grow and get stronger. When you’re dieting, you want to lose fat and also minimize the muscle loss. What will give your body the best reason to keep the muscles if not the same training that caused them to grow and get stronger?

I wrote that you don’t need to change almost anything. That’s because there is one thing you will need to change and it’s the volume of your training. The lowered food intake during fat loss phase can, and probably will, impact your recovery ability so you’ll be forced to lower the training volume.


Today we’ve looked at the one of the three most important parameters of the training set-up – intensity. Let’s summarize the most important information for quick reference.

The rep ranges you should use the most in your training depend on your main goal:

Goal Reps per set
max strength 1 – 6 reps
build muscle 6 – 20 reps
muscular endurance > 20 reps


When you use one rep range for a few weeks (8 – 10) your body becomes adapted to it and it won’t stimulate your muscles as much as at the beginning. To fight this adaptation it’s beneficial to use also other rep ranges (aka intensity), from time to time, for a few weeks (3-4).

If your main goal is to lose fat you don’t need to change almost anything because the same training that builds muscle/strength will also help you to keep the muscle/strength during dieting. One variable you might need to change is training volume because the lower energy intake can hamper your recovery.

I hope you’ve found the content of this article helpful. If so, please like and share the post. In case you have any question, suggestion or your own experience you’re more than welcome to leave a comment. Thank you:)


  1. Jasmere

    Being a former personal trainer, I can vouch for the information provided here. I think the one thing that always gets me is when people assume that in order to lose fat they just have to run more and that simply isn’t true. Weightlifting can and will help tremendously in that respect. What’s even better is that if you gain hard enough like you said, you can actually get a cardio workout by utilizing that intensity. I’d say this is pretty comprehensive without being too confusing for newcomers. Nice

    1. Marek (Post author)

      Hi Jasmere,
      great remark regarding getting the cardio workout with weightlifting. I’ve observed this myself. I don’t do almost any cardio yet my resting heart rate dropped significantly (think around 85 -> 65 bpm). And recently I’ve read about a study that also confirms this. Appreciate the comment and thanks for stopping by:)

  2. Timmysnakes

    Hey Marek
    Being a Fitness nut myself, I couldn’t agree more. I have found that for myself, I require longer periods of rest inbetween high intensity sets to fully recover my muscles and focus on strength. What do you think? Would be great if you could adress rest period in another post, it’s always and ongoing debate and I would love to hear your opinion. I found this post very helpful!

    1. Marek (Post author)

      Hello Timmy,
      agree with you 100%. Lifting really heavy is very tiring for the whole body and mind so longer rest is needed for sure. Great idea for the future post!:) Thanks for stopping by.

  3. Garen

    Hey Marek,

    I need to get back into lifting weights like I used to in my younger days.

    One thing that is so important with weight training is nutrition, too. Meaning you need to eat lots of protein and carbs to help fuel your muscles.

    I did have a question for you though? What do you think about supplements like creatine or glutamine? Any supplements you recommend for building muscle.

    1. Marek (Post author)

      Hi Garen, you totally should;)

      Regarding the glutamine, as far as I know, if you have sufficient protein intake you have enough glutamine. Even if the supplementation was beneficial on top of this protein intake the effect would be so small that it’s probably not worth your time and money. Creatine is great, it’s cheap and proven to work, go for it – simple creatine monohydrate is the best choice.

      I don’t know about other muscle building supplements except for creatine (and even that is not muscle building per se). Get your training and nutrition in order, throw in some basic supplements if you want and you’re set. No need to spend money on fancy supplements that most likely do nothing.

      I hope you’ll find this helpful:)

  4. Bronx

    what is the recommended work out for each muscle? Ex. arms do I work them 1/wk and how many days between do you wait before hitting that same muscle group?

    1. Bronx

      i found your other articles and you have cleared up ALL my questions, great articles! thanks…

      1. Marek (Post author)

        Hello Bronx, I’m happy to hear that! If you have any further questions don’t hesitate to ask:)


Leave a Comment

Your email address will not be published. Required fields are marked *