Light Weight, High Reps For FAT LOSS. Heavy Weight, Low Reps For SIZE: Myth Or Fact?!

If there has ever been an assumption that I have seen regurgitated time & time again in the fitness industry it is this one. Is using light weight & high reps better for fat loss? And should heavier weights & low reps be prioritized when building muscle size is the goal?

Before we delve into either statement, it is important first to understand the underlying mechanisms that actuate fat loss & muscle hypertrophy (building muscle).

Fat loss is brought about simply by eating a hypocaloric diet; eating less calories in your diet than it takes to maintain your bodyweight. If we facilitate a deficit, regardless of whether we are lifting weights or not, fat loss will occur. A lack of engagement in resistance training & an insufficient consumption of dietary protein will catabolize (break down) muscle alongside body fat. Which alludes to the difference between weight loss & fat loss, a topic that I have delved into in a previous article that you can find here.

Building muscle on the other hand, is facilitated by engaging in a resistance training program that encourages progressive overload (increasing the stress placed on the muscles over time in some capacity) and consuming enough dietary protein. In order to maximize our bodies potential to build lean muscle, it is also advisable that we eat a moderately hypercaloric diet; consuming more calories than it takes to maintain our bodyweight. The word “moderate” is used in this case to emphasize a slight surplus of calories, with the goal being to build as much mass as possible while mitigating fat accrual, although some gained will be inevitable.

Now that we have established the mechanisms of both, we can dive deeper into the first statement:

“Low weights & high repetitions are best for fat loss.”

Bluntly put, we can perform thousands upon thousands of repetitions a day, for weeks and months on end. If we are eating too many calories, we can gain weight despite our efforts in the gym! Resistance training builds muscle, it does not burn fat. A hypocaloric diet burns fat. A common misconception some people have is incorrectly correlating the intense burn that comes from lifting light weights for many reps as “fat being burned”. This unfortunately, could not be further form the truth. The intense burn is nothing more than lactic acid accumulating in the muscles, a natural by-product of anaerobic training (anaerobic means “without air” & refers to the muscles generating energy absent of oxygen).

On the other hand, let us examine the second statement; heavy weights & low reps are the best for building muscle size.

Building muscle is simple. We need to ensure that we are inducing progressive overload in some way during our training. In addition to that, we need to train close to form failure. Form failure advocates that we perform as many repetitions as possible on an exercise & only stop when our technique begins to falter. Continuing past that point only serves to increase injury risk. Does this mean we need to take ALL our sets to failure? No. But, we do need to take them close to it. Stopping about 1-2 reps shy of this point in most of your exercises is a good guideline to abide by. It will ensure that we are training hard enough to stimulate muscle growth without risking injury unnecessarily.

Therefore, regardless of the weights & reps that we train for, provided we are inducing progressive overload (increasing the stress placed on our muscles over time e.g. By increasing reps, weight, improving our form, adding sets, manipulating rest times and/or exercise tempo, increasing training frequency etc.) and taking all our exercise at least 1-2 reps short of form failure, we will build muscle.

Aim to use both light weights for high reps & heavy weights for low reps. They each have their own benefits. Light weights are less strenuous on the connective tissues (tendons and ligaments). They have also been theorized to promote sarcoplasmic hypertrophy (increasing the size of muscle cells by increasing their volume. Sarcoplasm, glycogen & water are all stored in larger amounts which gives the muscles a “fuller” appearance). They are also excellent for honing in on technique & achieving a more pronounced mind muscle connection (the sensation of feeling the target muscles working in an exercise).

Heavy weights & low reps on the other hand, are excellent for building strength. They also thrash the fast twitch muscle fibers, which have the greatest capacity for size & growth.

Use your diet & particularly your calories, to lose fat. Use your training & particularly a program, that utilizes progressive overload, a variety of rep ranges & weights (both high & low), with all your sets taken close to form failure, to build muscle size.

That simple 😛