The short answer

In a fat loss phase, if your own enjoyment isn’t taken into account. It’s my belief that you’d technically be better doing slightly higher reps (usually in the realm of 8 to 15) so being you continue to take your working sets close to failure. This way you’ll preserve muscle, while placing less stress on your joints and lower your risk of injury under diet fatigue when compared to lifting with lower reps and higher loads.

**Watch out for the bullsh*t**

High reps don’t tone. Toning = less fat and more muscle.
High reps don’t create striations or harden muscle. Definition = low body fat + muscle size.
You don’t sweat out fat. Sweat is water/electrolytes.
The difference in how many calories you burn between low vs high reps is trivial. Your fat loss is driven by your sustained nutritional habits and your daily activity (your training, steps, non exercise activity).

What rep ranges actually grow your muscle?

5 to 30 reps, if you’re near failure.

I appreciate that your initial thought might be “Wtf? Why is it such a large spectrum? Surely there’s a clearer, more specific target I should be aiming for?” But no.

This section of the P+P playbook isn’t strictly about rep ranges, but I think this is worth mentioning because it ties into the bigger point I’m about to make. If we want to get a little sciency for a second:

Muscle growth is driven by mechanical tension applied with enough intensity over time, paired with progressive overload (gradually demanding more from the same movement over weeks and months).

Mechanical tension is simply the amount of force your muscles generate to overcome resistance. But for that force to translate into growth, the exercise itself needs to be standardised, which means consistent form, range of motion and tempo so that any increase in load or reps actually reflects more work, not just looser technique.

So rep ranges are just a tool. But, here’s where things get slightly nuanced.

You can technically grow muscle doing sets of 30 reps the same way you can with 5 so long as both are taken close enough to failure. The difference is how they work.

How do rep ranges work?

Lower rep, heavier loads: Produces greater mechanical tension per rep. That tension is the main driver behind long term muscle growth, especially when the goal is building an aesthetic, stronger physique. Heavier work also tends to push strength up faster and that increase in strength raises your long term ceiling for progressive overload. Which means you can apply more tension in future sessions.

Higher rep, lighter loads: Still stimulates muscle growth, but it does so with less tension per rep and more fatigue. Past a point, the challenge can shift from your muscular effort to your cardio or mental endurance. So while sets of 20 to 30 reps can stimulate growth if pushed close to failure, they’re generally a less efficient route for maximising mechanical tension and long term progression.

What if growth isn’t the goal?

If you’re reading this, your goal right now isn’t to build new muscle. It’s to hold onto the muscle you already have. The best way to do that is by continuing to lift heavy enough to create meaningful mechanical tension whilst also catering to the fact, that during your fat loss phase your recovery resources are lower, your joints might feel more sensitive and your fatigue will accumulate quicker. Therefore, slightly higher rep ranges (8 to 15) make sense. You’re still training close to failure, still generating high amounts of effort, but you’re doing it with less joint stress and a lower risk of injury compared to grinding 3 to 5 rep sets. So while lifting heavy remains important, it doesn’t need to mean 1 rep max heavy. It just means challenging enough to keep tension high and technique standardised.

The pros & cons of doing 8 to 15 reps my bodybuilding prep

During my prep, I experimented with higher reps and lighter loads working mostly in the 10 to 12, 12 to 15, and 15 to 20 ranges. Yet, I found I simply didn’t enjoy it. I eventually settled into 8 to 10 for most compound lifts and only worked at 10 to 12 or 12 to 15 reps on the isolation exercises of a session. So if you’re in a fat loss phase, here’s how I’d break it down based on my own experience:

Pros

1. You still keep mechanical tension meaningful
Loads in the 8 to 15 range can still be heavy. You’re not coasting, you’re picking weights that let you stay close to failure without grinding through 5 rep sets that can batter your joints and connective tissue. Especially when you’re in a deficit and recovery is compromised. If you’re advanced, you could still work in some 6 to 8 sets early in the session (just make sure you’re properly warmed up and have trained under fatigue before). Otherwise, 8 to 15 is a good balance between tension and tolerance.

2. It’s sustainable when calories are low
When food is limited, you won’t have the same energy reserves or patience for marathon sessions. Sticking to 8 to 15 keeps your workouts productive without dragging on forever. You’re in, you’re working hard and you’re out. All while giving your muscles enough stimulus to stick around.

3. Safer and easier on joints
Even with good form, heavy low rep work carries higher risk when fatigue builds. Staying in moderate rep zones lets you train with intent and intensity, but with a buffer of control. For me, this was key. There was a period of time, 9 months prior to the show where I was consistently getting injured (due to inadequate recovery). So staying injury free across the entirety of prep was FANTASTIC.

Con*

1. Mental fatigue hits harder than physical sometimes
There were days, especially late in prep, where just the idea of another 15 rep set felt miserable. You’re tired, hungry and the last thing you want to do is spend a full minute grinding out unilateral curls when all you can think about is food. High rep isolation work in particular can test your patience more than your muscles. When that happened, I’d often bring the reps down. Not to make things easier, but to keep my effort and focus high because I found it more enjoyable.

Final Take

Enjoyment drives consistency. Train in the rep ranges and with the exercises you enjoy and are effective. That’s what you’ll repeat and that repetition delivers your results.

You Want To Lose Fat. Should You Do High Or Low Reps?