How Little Protein Can You Eat Without Losing Muscle?

Maybe you’re having trouble finding high protein foods. 

Maybe you’re traveling and can’t stick to your normal meal plan. 

Maybe you’re simply tired of eating lots of protein and would rather eat more carbs and fat for a few days. 

If you’ve ever found yourself in one of these situations, you’ve probably asked yourself this question: 

How little protein can you eat without losing muscle?

After all, eating sufficient protein (usually defined as one gram per pound of body weight per day) is considered a canon of gaining and maintaining muscle. And, of course, you should generally eat a high-protein diet to maintain a lean, muscular body.

But if for some reason it’s difficult to meet your protein needs, how low can you go?

Keep reading to get evidence-based answers to these questions.

Table of Contents

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• What Is Protein?
• Why Is Protein Important for Weightlifters?
• How Little Protein Can You Eat Without Losing Muscle?

What Is Protein?

A protein is a large molecule made up of chains of smaller compounds called amino acids. 

You can think of amino acids as the “building blocks” of many bodily tissues, including muscle, hair, nails, and skin. 

They also play a crucial role in many bodily processes. For example, they help you maintain healthy bones, bolster your immune system, and repair cells throughout your body.

Your body is able to create 12 amino acids but must obtain the final 9 from the food you eat. This is why you must eat protein to survive.

Why Is Protein Important for Weightlifters?

Weightlifters require more protein than less active people to ensure their muscles recover from training and grow larger and stronger.

While the exact amount remains under scientific debate, most experts agree that weightlifters should eat at least 0.8 grams of protein per pound of body weight per day (g/lb/d) to maximize muscle growth, though more is likely better. 

How Little Protein Can You Eat Without Losing Muscle?

Hitting your daily protein target isn’t always possible.

For instance, it can be challenging to find high-protein foods and supplements while on vacation, making it difficult to reach the suggested 0.8 g/lb/d.

In such situations, you might shift your focus from aiming for optimum protein intake to support muscle growth to consuming just enough to maintain your muscle.

But how much can you decrease your protein intake without jeopardizing your gains?

Several factors, including calorie intake, training frequency, and weightlifting experience, can affect this number, making it tough to provide an exact figure.

If you’re new to weightlifting (you’ve been training for 6 months or fewer), studies show that you probably don’t need to eat much protein to prevent muscle loss.  

For example, in a study conducted by the University of Illinois, new weightlifters who trained twice weekly and consumed just ~0.4 g/lb/d lost just a pound of muscle during a 4-month(!) diet. 

In another 4-week study conducted by scientists at McMaster University, novice weightlifters who trained twice weekly, ate in a calorie deficit, and consumed just ~0.55 g/lb/d for 3 weeks gained a modicum of muscle. 

Therefore, provided new weightlifters continue training, they likely only need to eat ~0.5 g/lb/d to maintain muscle while dieting. Since the body needs less protein to preserve muscle when maintaining or bulking, beginners could potentially consume a bit less than ~0.5 g/lb/d when not in a calorie deficit (though it’s not clear exactly how much less protein is needed when eating at maintenance or in a deficit).

This isn’t enough for seasoned weightlifters to avoid muscle loss, though. 

For instance, in a study conducted by the University of Birmingham, athletes who continued to train 4-to-5 times weekly and ate 0.45 g/lb/d lost 3.5 pounds of lean mass, including quite a bit of muscle, during a 2-week diet.

Most research suggests a more fitting figure for weightlifters who’ve been training a year or more is ~0.7 g/lb/d. 

In a study published in The International Journal of Sport Nutrition and Exercise Metabolism, researchers found that eating ~0.7 g/lb/d was enough for weightlifters to maintain all their muscle after a 2-week weight-loss diet. 

Likewise, in an older study published in the International Journal of Sports Medicine, researchers found that experienced weightlifters who ate ~0.7 g/lb/d during a week-long weight-loss diet maintained a positive nitrogen balance—an indicator they didn’t lose muscle while in a calorie deficit. 

Another small study published in the International Journal of Sport Nutrition and Exercise Metabolism found similar results—experienced weightlifters who ate ~0.7 g/lb/d for 2 weeks while dieting to lose fat lost an insignificant amount of muscle.

Again, given that ~0.7 g/lb/d is enough to maintain muscle in a deficit, we can be pretty sure that ~0.7 g/lb/d is enough to preserve muscle while eating maintenance calories. In fact, you can probably go as low as 0.5 g/lb/d if you’re an experienced weightlifter eating at maintenance or in a calorie surplus.

To sum up: 

• If you’re new to weightlifting (you’ve been training a year or less), you can eat as little as 0.5 g/lb/d while cutting, and probably even less than this while eating at maintenance or in a calorie surplus. 
• If you’re an experienced weightlifter (you’ve been following a structured strength training program for a year or more) and in a calorie deficit, aim to eat at least 0.7 g/lb/d.
• If you’re an experienced weightlifter eating at maintenance or in a calorie surplus, you can probably eat less than 0.7 g/lb/d (0.5 g/lb/d is a good estimate), but there isn’t much data to show this is the case.

There are a few riders that go along with these recommendations: 

First, all of this assumes you’re resistance training at least once or twice per week. This is an important part of muscle retention since it signals to your body that your muscle is necessary and worth preserving. This is particularly important when eating in a calorie deficit.

Second, all of this assumes you’re going to be eating this way for at least a week or more. You can safely reduce your protein intake to essentially zero for a day without losing an appreciable amount of muscle, so a couple of days of eating very little protein (such as a calorie-filled weekend vacation) poses no risk to your muscles. 

Third, if you’re like most people, the most likely scenario in which you’ll be eating very little protein is if you’re on vacation and eating a lot of high-fat, high-carb foods. While it may not seem like it, most of these foods still contain enough protein to easily get you over the 0.5 g/lb/d mark.

For instance, let’s say your breakfast consists of half of a baguette (440 calories, 17 grams of protein), two ounces of full-fat cheese (224 calories, 14 grams of protein), and a croissant (230 calories, 5 grams of protein).

Lunch is a big bowl of pasta in cream sauce (900 calories, 20 grams of protein) and a cup of gelato for dessert (470 calories, 9 grams of protein). 

Dinner is a large bowl of risotto with cheese and peas (900 calories, 22 grams of protein), four breadsticks (560 calories, 16 grams of protein), followed by a chocolate bar (440 calories, 6 grams of protein). 

Despite eating essentially no high-protein foods (even cheese is primarily fat), this indulgent vacationer consumed 109 grams of protein. That’s about 0.55 grams of protein per pound for a 200-lb man. 

If you’d like even more specific advice about how much of each macronutrient, how many calories, and which foods you should eat to reach your health and fitness goals, take the Legion Diet Quiz. In less than a minute, you’ll know exactly what diet is right for you. Click here to check it out.