by Chris Shugart

The Bodybuilder Study

Fat loss is great, but not if you’re also losing muscle. Here’s what we can learn from a new study on competitive bodybuilders.

Most people want to lose some fat. But wanting to lose fat and having the goal of losing fat are two different things. I want to speak Japanese. I don’t have the goal of speaking Japanese because, well, I’m not doing a darn thing to learn the language. And that’s how most people think about losing fat.

Bodybuilders and dedicated fitness fanatics are different though. They take action. In fact, when they decide to lean up, their biggest concern is losing fat too quickly. Why? Because rapid fat loss usually comes with muscle loss, and muscle loss comes with metabolism disruption and fat regain. Not good.

So, how quickly can you lose fat without losing muscle? That’s what the researchers wanted to find out in this new study using actual bodybuilders.

The Study

This Korean study used amateur bodybuilders who’d all just finished a “bulking” phase. Researchers recruited 26 natural competitors, divided them into two groups, and put them on different diets for 6 weeks:

• Moderate Dieters: These guys were given a diet that researchers hoped would cause a 5% loss of body weight.
• Severe Dieters: These guys were given a stricter diet that researchers hoped would cause a whopping 15% loss of body weight.

Unfortunately, the researchers didn’t provide any diet details, like calorie or macro intake. We can only assume that both groups were put into a caloric deficit. The severe group was just prescribed an even lower-calorie plan.

Both groups did the same free-weight workouts and treadmill sessions, so only the diets differed.

What Happened?

When you look at studies like this, it’s important to keep something in mind:

When we talk about “fat-free body mass” and “lean body mass,” that’s not just muscle. It’s also body water and even things like your bones and organs. So, good studies also measure water weight to give us a clearer picture of what’s happening. They call this “dry fat-free mass.”

So, here’s what happened when we account for the body water losses:

Moderate Dieters:

• Lost 11 pounds of total body weight.
• Lost 4.5% body fat (they went from 12.5% to 8% body fat on average).
• Lost 2 pounds of body water.
• Retained all dry lean body mass.

Severe Dieters:

• Lost 26 pounds of total body weight.
• Lost about 6.5% body fat (15.5% to 9%).
• Lost 7 pounds of body water.
• Lost 4 pounds of dry lean body mass.

What Can We Learn from This?

First, anyone who wants to get ripped would be happy to lose 26 pounds of scale weight. But what’s that scale weight composed of?

In this study, it was composed of 7 pounds of water, 4 pounds of muscle, and 15 pounds of fat. The fat loss is good and the water loss is almost meaningless, but the muscle loss will suppress the metabolic rate and could lead to a quick regain of the body fat. And, of course, they now need to build back 4 pounds of muscle just to be back where they started before their diets.

The moderate dieters lost 9 pounds of pure fat (11 pounds total minus 2 pounds of water) but didn’t lose any muscle during the 6-week diet. Their metabolic rate is preserved, and they probably won’t gain the fat back easily.

The severe dieters, on average, went from about 16% body fat to 9% in just 6 weeks, but it came at a price. T Nation contributor Bill Campbell, PhD, examined this study in his Body by Science newsletter and said that this rate of fat loss is simply too fast.

Second, if you’re going to do a severe diet, don’t do it for 6 weeks or more. The more calorie-restrictive a diet is, the shorter it should be. Otherwise, muscle loss becomes more of a risk. There’s a time and place for severe diets, but based on the evidence, it’s better to keep them at 4 weeks or fewer. Ideally, just take it slower.

The moderate dieters lost almost 2 pounds of fat per week. That’s nothing to scoff at! You may lose more than 2 pounds in the first week of dieting (especially on a lower-carb plan) because of accompanying body-water loss, but after that, 1-2 pounds per week is a good goal that should keep your muscle mass intact.

How Else Can I Prevent Muscle Loss?

Keep your protein intake high. While we need only .7 to .9 grams of protein per pound of body weight daily for muscle protein synthesis, more is better if fat loss is your goal. Shooting for 1 gram per pound of body weight is always a good idea, and some experts recommend a little more. Extra protein itself is thermogenic and protein keeps you satiated longer.

Ideally, use a micellar-casein-containing protein powder to reach those goals. Micellar casein is not only a muscle-builder, but it’s also the only protein shown to be anti-catabolic (prevents muscle loss). You can get micellar casein in MD Protein.

Or, instead of using a continuous diet where you eat the same number of reduced calories every day, try what’s called a non-linear approach. This strategy was shown in studies to prevent muscle loss. There are two ways to do it:

Traditional Non-Linear Diet: Diet extra hard on weekdays (reduce calories 35% below maintenance) then eat maintenance calories on weekends. This is sometimes called a “5/2” strategy. Get all the details here: The Non-Linear Diet for Lifters.

The 5/2 Protein Diet: This variation flips things around: eat maintenance calories on weekdays, then diet super hard on weekends using a type of protein fast. Get the details here: The 5/2 Protein Diet.

Reference

1. Kim, et al. “Effect of bodybuilding athletes’ weight loss method on performance factors and immune function.” J Exerc Rehabil. 2023 Dec; 19(6): 357–362.