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Does Your Body Burn Fat or Muscle First? (Science-Based)

Connor Sellers
Published by Connor Sellers
Fact checked by Donald Christman, BHSc FACT CHECKED
Last updated: September 2, 2022

As a fitness coach with a decade of experience, I’ve helped many clients achieve their ideal body fat percentage without compromising their muscle mass, mainly through targeted and intense strength training, a high-protein diet, and adequate rest.

So, when a friend disclosed how he lost muscle while trying to get his body fat percentage to Ronnie Coleman levels, I had to look into it.

This report compilation is the result of my thorough investigation of the subject matter. I also consulted a highly acclaimed physical therapist for this report.

Let’s dive in.

Quick Summary

  • Your body burns fat first before turning to muscle tissue, but it's not that straightforward.
  • Healthy eating, strength and resistance training, and giving yourself enough recovery time is the perfect remedy for burning fat and building and preserving muscle.
  • Fatigue, rapid weight loss, or not losing weight despite your best efforts are signs that you’re burning muscle instead of fat.

Which Burns First, Fat or Muscle?

A person squishing their belly fat

Fat burns first, usually long before muscle.

However, your body may still choose to burn muscle, but this happens only after glucose is depleted, and either your fat percentage is too low, or your body is poorly fat-adapted [1].

Although breaking down fat stores is a priority, your body's first choice of preference is carbohydrates.

This is mainly due to the fact that carbs are easily accessible and “combustible”.

Now, the second option, after carbs have been used up in the body, is glycogen. Glycogen is the glucose stored in the liver and muscles [2].

Only after glycogen stores start to get low does the body turn to fat stores for energy. 

After burning fat, the next stop is muscle tissue. So, technically, fat goes in first when glucose and glycogen are unavailable in sufficient quantities.

This brings us to the million-dollar question.

Can You Maintain Muscle Mass in Weight Loss?

Yes, you can maintain muscle mass in weight loss, but you’ll have to follow strict eating and fitness guidelines to preserve muscle while burning fats.

How to Lose Fat

A fit person holding a salad bowl with a measuring tape around her stomach area

To lose fat, you only need to consume fewer calories than your body burns. Exercising, especially aerobic training, speeds up getting rid of fat.

However, if you overdo or don’t consider incorporating strength training into your exercise regimen, you might end up losing both body fat and muscle mass.

Additionally, you need to be careful not to lose weight too fast as it may also result in muscle loss. Instead, work on losing small amounts of weight weekly for extended periods.

Forget about targeting losing fat in certain parts of the body. It rarely works. Instead, focus on lowering your overall fat percentage.

How to Maintain It

A buff person stretching a resistance band

To minimize muscle loss, you must balance between pushing hard and limiting yourself.

1. Resistance Training Exercise

A study examining the effect of calorie restriction in combination with endurance and resistance training in adults with obesity, found that when people added these exercise plans to their diet, it prevented muscle loss [3].

“Exercise is key to weight loss,”

Bartolome Burguera, Endocrinologist, MD, Ph.D

Additional studies show that resistance training workouts in combination with intermittent fasting can improve overall body composition and in particular, losing weight while retaining muscles [4]

2. Enough Recovery Time

When doing intense workouts, eat well and get enough rest time. Recovery time is just as essential as working out. So be sure to get plenty of sleep to restore your energy levels and allow the body to repair the muscle tissue.

3. Eating Healthily

If scientific studies are to go by, consuming enough protein diet puts you at a better chance of retaining lean mass while depleting those fat stores [5].

All in all, you need to balance resistance training exercises, a balanced diet with sufficient protein and calories, not overdoing some workouts like aerobic training, and getting enough recovery time.

But in case the unlikely happens and you start losing muscle tissue instead of fat, how would you know?

Related Articles:

Signs You’re Losing Muscle, Not Body Fat

A healthy person fatigued at the gym

You can always tell when you’re losing muscle tissue. And below are a few signs to look out for when this is the case.

Losing Weight Rapidly

Losing body weight rapidly is not a sign of losing more fat. You’re probably losing muscle instead of body fat.

Fatigue

When you feel more tired than usual, you’re possibly losing muscle.

Also, if you cannot lift the same weight you used to lift, or your muscles feel exhausted faster than before, you’re probably losing muscle instead of fat.

The Plateau Effect

The plateau effect is when you’re not losing fat despite your best efforts in working out and maintaining a calorie deficit.

If you feel like you’re in this state, you're probably losing muscle instead of fat.

FAQs

Build Muscle or Burn Fat, Which One Should You Do First?

It depends on your goals. If you have a high-fat body composition and have been adding lean body mass for a long time, you should focus on fat burning.

But if you’re slim, are new to strength training, or you’re concerned about your body image, you may choose to build more muscle first.

Is It Possible to Cut Fat While Still Building Muscle?

Yes, it's possible to cut fat and build muscle simultaneously. You can do this by sustaining a weight lifting program, maintaining a caloric deficit diet, and possibly by adding a high-quality fat burner into the mix.

Prioritize protein-rich foods as they are vital in building and maintaining muscle and fat loss.

Fat Loss and Muscle Gain

Losing fat and preventing the loss of muscles through strength training, sleeping enough, and eating healthy can feel like treading on a tightrope.

That's why I recommend a fat burner supplement that will keep you from worrying about burning muscle instead of fat:

These are not your average fat burners. We’ve thoroughly tested these products and found them to be effective. So you don't have to worry about any adverse side effects.


References:

  1. https://health.clevelandclinic.org/where-does-body-fat-go-when-you-lose-weight/
  2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3248697/
  3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5946208/
  4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4271606/
  5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4892287/

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