The Great Debate – Cardio vs Resistance Training for Leaning Out

Happy people working out in a cross-training gym using weights, boxes, and tires

If you want to get leaner you need to do more cardio, but if you want to develop muscle you need to lift weights, right? Not exactly, let’s look a little deeper!

First, lets distinguish “lifting weights” and “resistance training”.  People often associate “lifting weights” with bulking up and “resistance training” with toning up. Technically speaking, lifting weights and resistance training are the same thing! Regardless of where the resistance is coming from, weights, bands, body weight, machines, etc, the bottom line is to develop lean muscle you need to do higher intensity contractions than what cardiovascular workouts require.

The first part of that statement, “to get lean you need to do more cardio” is VERY, VERY FALSE!! But before I get into why it’s false, let me first distinguish the difference between cardiovascular and anaerobic (resistance training) workouts. “Cardio” is anything you can do for 3 minutes or more, such as jogging. Anaerobic, or resistance training, is anything that you burn out before 3 minutes, for example, push-ups.

To fully understand the benefit of both in terms of losing body fat, let’s look at the calories burned.

Cardio- technically does burn MORE calories per minute WITHIN the actual workout duration. The reason for this is because within the workout itself you never need to take a rest, so your body just keeps moving; your body temperature raises and stays there. BUT because the muscle contractions are low intensity, after you cool down from the workout (1-4 hours after you finish) your body goes back to its’ normal basal metabolic rate (how many calories you burn just being awake).

AnaerobicWITHIN the workout, you are going to burn LESS calories per minute overall because they are intense muscular contractions and you must take breaks reducing your average caloric burn per minute slightly…BUT due to the high intensity muscle contractions, your muscles BREAKDOWN (they get tiny microscopic tears). To repair those tears, you need to expend energy. So the difference is after your body cools down from the workout (1-4 hours after), you will have a slightly HIGHER basal metabolic rate for 24- 40 hours AFTER the workout, just due to repairs.

Let me give you just some basic numbers so you can compare the two styles. For cardio, an intense workout can range from 10- 20 kcal/min, while an intense anaerobic workout can range from 7- 17 kcal/min. Let’s take someone who burns 15kcal/min with cardio and 12 kcal/min with anaerobic:

  1. Cardio- 50min x 15 kcal/min= 750 kcal. Cool down- 4 hours x 3 kcal/min= 720 kcal. 40 hours after workout- BMR of 1 kcal/min= 2,400 kcal. Total kcal burned=3,870
  2. Anaerobic – 50min x 12 kcal/min= 600 kcal. Cool down- 4 hours x 3 kcal/min= 720 kcal. 40 hours after workout- BMR RAISED to 2 kcal/min= 2,880 kcal. Total kcal burned= 4,200

The difference is anaerobic burns 330 calories MORE than cardio.

A quick note: This is only if the two exercise sessions are of equivalent intensity. If the cardio is a tough session, while the resistance is an easy “going through the motions” workout, then your cardio will be more beneficial.

With that said, I’m not advocating to forget your cardio. Cardio does strengthen the most important muscle in your body, the heart. Also, due to the breakdown your body gets from resistance training, your body needs breaks, otherwise injuries can occur. So if you still want to be active, it can be a very healthy decision to supplement in low intensity contractions to give your muscles some time to recover! But when it comes to leaning out, if you are trying to prioritize which type of exercise to do, I would highly recommend spending more of your time doing resistance training rather than cardio.

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