One of the most common questions I get is “should I lift weights when losing fat or should I build muscle once I’ve lost the fat?” And the answer to this question is a resounding “you should lift weights when losing fat” — here’s why.
This all stems from a prevailing fitness misconception that you cannot build muscle in a caloric deficit and that you have to make the choice of losing fat or building muscle.
And although you CAN build muscle in a caloric deficit — especially when you are a beginner as your body has not experienced resistance training — a 30-45 minute weight training session can go a long way during your fat loss and in the future.
Why You Should Absolutely Lift Weights When Losing Fat
The only way to lose fat is to be in a caloric deficit; and to find out how much you should eat when dieting to lose fat, you need to figure out a rough estimate of your Basal Metabolic Rate (BMR) — how many calories your body needs per day at rest — then take off 20-30% of the total calories of your BMR to find a sustainable caloric intake when dieting.
Of course, on days you perform vigorous exercise, you can increase the total number of calories you can consume.
The go-to rough estimate to calculate your BMR is to multiply your bodyweight in pounds by 15.
If you weigh 200lb then your BMR should be around 3000 calories per day (200lb x 15 calories).
To lose fat at a sustainable pace or around a pound per week, you should aim to consume around 500 calories per day under your BMR. For this hypothetical 200lb dieter, that would be (3000-500kcals = 2500kcals per day) 2500 calories per day at rest.
Alternatively, he can adopt another rule and consume 20-30% fewer calories per day if he wanted to lose more fat. This would put him in the 2100-2400 calories per day range (20-30% of 3000 = 600-900 calorie deficit per day).
Although we have written about methods you can employ to raise your BMR in the past, the number one way to boost your metabolism — by far — is to build muscle.
Each pound of lean muscle gained will raise your BMR by 20-30 calories.
Let’s say you train hard for multiple years and gain 30lb of muscle all over your body. You could burn an additional 600-900 calories per day AT REST.
Furthermore, if you were to do cardio, bigger muscles require additional energy expenditure to contract while carrying around more bodyweight. Therefore, a cardio session for a well-built beefcake, ceteris paribus, will be more calorically expensive than for a skinny beanpole — even if they traveled at the same speed, at the same resistance, for the same period of time.
In other words, you will become far more efficient at burning calories as you build more muscle — which is why you should definitely lift weights when losing fat.
Somebody completely new to lifting weights who is out of shape will benefit from build muscle when trying to shed excess fat.
Newcomers can put on 10-20lb of muscle in their first year of training — drug free — if they put in the effort.
This could translate into raising their BMR by up to 600 calories!
And you would struggle to burn 600 calories in an hour of hard cardio — imagine doing an hour of hard cardio a day, without having to do it at all!
Lifting weights, in itself, will burn around 200-300 calories per hour.
Plus, when you finally reach your target weight, you will already have foundational muscle mass to work on, saving you time in future.
Not only that, but you will be also able to eat larger quantities of food without gaining fat.
As somebody who used to be obese, I used to be susceptible to relapses every now and then. My muscle mass would have mitigated a lot of extraneous fat gain in hindsight.
TIP: Hit your squats and deadlifts every week to promulgate the greatest muscle growth possible.
Conclusion: Why You Must Lift Weights When Losing Fat
We have previously stressed the importance of doing cardio when losing fat — it makes the experience more bearable.
Likewise, you should lift weights when losing fat for that very same reason — to make the experience more bearable.
Not only will you be able to consume more calories when losing the same amount of fat, burn more calories while performing cardio, you will also help preserve and grow valuable muscle mass while your body attempts to reduce your BMR to accommodate for the prolonged caloric deficit you are undergoing to reach a target weight.
Studies have also shown that you should lift weights when losing fat with a long term view in mind as cardio has to be performed on a regular basis for calories to be burned, while muscle burns calories simply by existing.