Cardio or weight training for fat loss?

When looking to lose weight, should you choose cardio or weight training?

The answer might come as a surprise. Although cardio makes you sweat and feels like you’re putting in a lot of work (burns a ton of calories), it’s usually a good idea to prioritize resistance training when dieting to lose weight. Yep, resistance training over cardio. I'm going to explain in detail why, and it might change how you think about calories, dieting, and exercise for weight loss.

I talked about the Principles of Energy Balance before, and you may have heard of "Calories In vs. Calories Out" or "Eat less move more". When you eat more calories than you burn, you will store that extra energy (calories) as fat in the body. Eating fewer calories than you burn will result in fat loss.

So you might be thinking, "Yeah well Megan, that's why I want to do more cardio to lose weight because I'll burn more calories!" But here's why resistance training should be prioritized.

First, your body adapts to cardio crazy fast. Meaning the first run you do, you'll burn the most calories. But over time, your body becomes really efficient at running, so you have to run longer or faster to burn the same number of calories as your first run.

Second, when you want to lose weight, you really want to lose fat. And you want to do this mainly through nutrition - you want to modify your diet to be in a calorie deficit (eating fewer calories than you burn). We're busy humans who have day jobs. We can't exercise for four hours a day to burn enough calories to eat whatever we want. That's why we modify our nutrition first - the “calories in” part of the equation. It's just more time-efficient.

So you've got your nutrition dialed in, and you're tracking your calorie/food intake in some way. When you're in this calorie deficit, you lose fat. But you also lose muscle mass when you’re in a calorie deficit. Resistance training and eating adequate protein help to mitigate muscle loss during a fat loss phase (adequate protein is approximately .8-1g/lbs of body weight).

So you might lose more weight doing cardio and eating less, but more of the weight will have come from your muscle than if you had been resistance training. We want to keep the muscle because that's what gives us shape and firmness and plumpness and all the good things.

So if you're only doing cardio and you're eating fewer calories, you're not giving your body any reason to hold onto your muscle mass. Our bodies have evolved to adapt to the stress placed on them by the environment. This makes the body resilient to that stressor the next time it's encountered. Basically, your body says "This chick has been lifting heavier and heavier rocks for three weeks. We need to grow these muscles bigger, otherwise she'll eventually be crushed by the rock..." or something like that. Resistance training will help your body maintain muscle, and the weight you lose will come primarily from fat stores.

Now, the other thing to mention is that muscle mass increases your Resting Metabolic Rate (RMR). This is just a fancy term for calories burned at rest - calories that are used for bodily functions. Having more muscle means your body has to use more calories from your food to maintain that muscle. Which is awesome, because you're burning more calories just sitting there looking jacked and tan.

Now as you diet, your RMR decreases (this is normal), because your body recognizes that you're not taking in enough calories, this is sort of a survival thing. So if you're only doing cardio and no resistance training, your RMR decreases even further as you lose more muscle mass. Making it harder to continue to lose weight.

Another thing: past the age of 30, you lose muscle mass at a rate of 3-5% per decade, a natural part of aging called Sarcopenia. Resistance training becomes even more important as you age to stave off natural muscle loss.

Sidenote: I'm not saying never do cardio. Cardio has a time and place in your exercise routine and fitness journey. And if you love a specific form of cardio, I will always say to sprinkle it in either after resistance training or on separate days.

As you continue your fat loss phase, your rate of fat loss will naturally slow down due to decreased RMR and a decrease in something called NEAT - non-exercise activity thermogenesis. Your body will naturally not fidget as much, you won't walk around as much, etc. You won't even notice this, but it's your body's way of preserving your energy as much as possible when in a calorie deficit. This is yet another reason to use weight training to keep RMR higher while you diet.

So to recap:

• When we want to lose weight, we really want to lose fat and preserve muscle (or maybe even build muscle).

• We do this through a calorie deficit - modifying our nutrition so we eat less than we burn because nobody actually has time to spend a bazillion hours in the gym.

• In order to preserve muscle mass while we diet, we should weight train and eat adequate protein at about .8-1g per pound of bodyweight.

• The added benefits of resistance training beyond maintaining lean muscle mass are increased resting metabolic rate and added shape and firmness to the body.

• It's also good for your bone health as you age!

• If you love cardio, sprinkle it in, but prioritize weight training.

If you got this far, thank you for reading. I'd love to know if you currently have a cardio regimen, resistance training program, or both. Comment below and let me know. And as always, I'm here for any questions you might have.

Chat soon.