As a team of sports dietitians seeing everyone from active females to elite athletes, one topic we frequently have to explain to our clients is- what happens if you don’t get enough protein while working out.

Understanding ideal protein intake is incredibly confusing because of the polar opinions that people often hear. Some of the confusion surrounds thoughts such as:

“Having a protein deficiency on a regular basis will help you live longer.”

“If you don’t eat enough protein, you’ll never build adequate muscle.”

“If you eat too much protein, you’ll blow out your kidneys!!”

“Protein shakes make you gain weight. Plus, Americans overeat protein anyway.”

“You should only consume plant-based protein.” 

“You should eat only animal products to get enough protein and have energy too.”

So much information is thrown our way about protein these days; it’s hard to know what to believe.

Why You Should Trust Us on Answering what happens if you don’t get enough protein while working out

If your brain is running a million miles a minute, let us help you streamline this topic. We work hand in hand with clients of all types. know the research, and can tell you exactly what works and what doesn’t work.

We don’t just work hand in hand with active individuals and recreational athletes, though. One member of our team is an NBA dietitian nutritionist and knows firsthand what happens to ELITE athletes when they don’t get enough protein throughout the season.

Whether you’re a mildly active individual or a beast in the weight room, we can help you understand what happens if you lift weights but don’t eat enough protein, what happens if you don’t get enough protein while working out, and EXACTLY how to overcome this issue.

Right now, Let’s address one of the most essential questions regarding protein: What happens if you don’t get enough protein while working out?

How Much Protein Do I Actually Need?

First, let’s briefly discuss how much protein you actually need. After all, how do you even know that you’re getting enough protein each day if you have never actually stopped to calculate your needs?

While nothing can ever take the place of working one on one with a registered dietitian who can help you map this out according to your goals and lifestyle, this quick cheat sheet is an excellent starting point:

First, let’s take your weight in lbs and divide by 2.2 to give you kg of body weight.

Infographic explaining how to convert lbs to kgs in order to determine the recommended protein intake for athletes.

Alright, now, let’s break this down into categories, this is how we, as sports dietitians, would help you to break down your protein needs:

Light physical activity 3-4 days a week:

1.0-1.3 g/kg

Moderate physical activity


Intense physical activity:


Intense strength training, going through a bulking phase, or you are in a situation where you need to cut fat mass and preserve lean mass for a brief period:


(And yes, for you the protein geeks and those wondering what happens if you lift weights but don’t eat enough protein who saw the study that recommends even higher than 2.3g/kg, keep reading as we will soon reference this information below.)

Decide which category you fall under, and use this to calculate your specific needs. Keep in mind that your needs will likely shift throughout the year or your sport season. 

Women will generally fall towards the lower end of each range and men towards the higher range.

Here is an example: A male athlete who weighs 180 lbs and is moderately active.

180 / 2.2 = 82g/kg

82g/kg x 1.6g protein/day = 130g protein/day

Infographic explaining how much protein someone needs when working out.

What Happens if You Don’t Get Enough Protein While Working Out

OK, time for the main event: What happens if you don’t get enough protein while working out?

While many issues can arise if you don’t get enough protein while working out, these are the top three most common issues we see in the trenches of sports nutrition:

1. You Will Feel Tired and Sore

For starters, on the most basic level, you will likely feel significantly more tired and sore than you should.

This happens because muscle is broken down when you work your tail off in the gym, but there is insufficient protein to repair and rebuild those worn-down muscles. This theory holds for just about any concept in life- how can you expect your car to keep running if your gas is on E? 

When daily protein intake is on point, especially when this includes immediately post-workout is adequate, you may notice that you do not experience muscle soreness. Or, if you do, it’s brief and mild in nature. 

On the other hand, if you don’t get enough protein while working out, you may experience muscle soreness for the next 3-6 days.

As you can imagine, this is not advantageous to performance. Afterall, how can you make the most of your next training session when you are super sore?

2. Struggling to Gain or Maintain Muscle

Next, you may find yourself spinning your wheels when it comes to muscle gain, and for some, even maintenance will be a struggle if you are not consuming enough protein to keep your body properly fueled.

This is why sometimes you may see an athlete crushing their workouts yet not having much to show for it regarding body composition. 

Simply put, the more lean muscle you have on your body, the more calories your body needs and utilizes to keep those muscles fueled.

3. Constant Hunger

Insatiable hunger is an interesting one because it’s common, yet most active individuals don’t connect the dots. It is more than possible to eat enough TOTAL calories to support your body’s energy demands each day,

BUT if your macronutrient ratio is off, meaning you are crushing carbs and including minimal fat, and especially minimal protein, you may find yourself in a constant state of hunger, despite eating every few hours.

Woman doing bent over barbell row exercise thinking about what happens if you lift weights but don't eat enough protein.

What Happens if You Lift Weights But Don’t Eat Enough Protein?

I’d like to address a similar question to what happens if you lift weights but don’t eat enough protein… What happens if you lift weights but don’t eat enough protein? This is another common question and it’s important that we adequately address this concern. 

As discussed previously, with a lack of protein, you can expect to feel sore, tired, and not quite as lean and or muscular as you desire if you lift weights but don’t eat protein.

Have you ever seen someone who workout like crazy but kind of looks flabby or skinny fat?

While its not always due to a lack of protein, this is often the case.

In fact, we’ve seen plant-based clients who were extremely upset about their body composition and when we had them keep a food diary they were only getting 15-25 grams or protein per day. How can your body build muscle fibers with that little protein?

So, what can you expet if you lift weights but don’t eat enough protein?

Here is a short list of things you’re likely to encounter with low protein intake while lifting weights:

  1. Decreased lean muscle mass
  2. Muscle atrophy
  3. Increased risk for overuse injuries such as tendonitis
  4. Increased risk for sprains and strains when running, doing plyometrics, Olympic lifts, or performing high-intensity
  5. workouts
  6. Decreased overall energy levels
  7. Decreased bone density
  8. Weakened immune system

Long-Term Damage Could Occur From Exercising But Not Getting Enough Protein

If you consistently take in less protein than you need, negative health consequences may occur you may notice hair loss and a weakened immune system.

Not to mention, you will experience greater muscle loss and weakness with age.

Now, what about those athletes who truly eat enough protein but still don’t feel like they are making progress with building muscle or limiting a loss of muscle mass?

Two Possible Causes for Poor Muscle Recovery or a Loss of Muscle When Trying to Get Enough Protein:

1. Gut Health is Imparing Your Ability to Digest and Asorb Protein

It is incredibly important to dive deeper into your gut health. In our practice, we constantly run advanced stool tests to see what works and is not working in someone’s gastrointestinal tract. 

Trust me on this one, you could have the most perfectly crafted diet and workout routine, and you could follow it to a tee.

However, if your gut is so imbalanced that it is not allowing you to digest and absorb a perfectly crafted diet properly, you will never see the progress you want.

For what it’s worth, low stomach acid is the number one gut-related issue we see in our practice that hinders the absorption of protein.

Quick side note: I just finished my last visit with one of my favorite clients. 3 months ago, he was chronically ill with recurring C-diff. He called me from his hospital bed to schedule our first appointment. He was down to 156 lbs with fatigue, brain fog, terrible gut issues, inability to eat normal adult portions and the inability to recover from his workouts. (Previously a lean 215 lbs.)

Mind you, he is an extremely skilled boxer and also a firefighter/EMT so he needed to be on his game at all times.

We worked closely over the last 3 months to change his diet a bit, but most importantly, I designed a protocol to rebalance his gut. At about the 2.5-month mark, all symptoms resolved and he is back up to 180.6 lbs as of today. 

He is now recovering like a boss, eating like a champ, and began to build lean mass once we corrected the gut- a perfect example of how your gut truly matters, and can overshadow a well-balanced diet and perfect training regimen. 

On the contrary, though, just a little reminder for you:  It is entirely possible to have ZERO gut symptoms but still have a gut that is not functioning optimally. Yes, you got it – that means zero bloats, fart, pain etc., but yet there could be plenty of underlying issues like infections, yeast overgrowth and poor bacterial balance that impede digestion. 

Infographic explaining potential causes of poor muscle growth and muscle repair including from inadequate protein intake.

2. Error in Calculating Protein Requirements or Understimating Protein Demands

In our professional opinion, the grams of protein generally recommended for athletes, especially those in strength and power sports, tend to be LESS than what these individuals need. 

However, not just strength and power athletes have this issue.

We regularly have clients such as John, a 58 yr old painter who works 10-hour days going up and down ladders, lifting supplies, etc, and then goes home to do a basic whole body lifting routine. John, and many like him, often underestimate their protein needs because they feel that since they’re not doing heavy Olympic lifts like meatheads in the gym they’re not really taxing their muscles much.

Someone like this is heavily taxing their muscles all day and will need to pay close attention to getting adequate protein to achieve full muscle repair from their daily work and workouts.

If you lift weights regularly, even if you don’t go heavy, check out the following information:

  • The American College of Sports Medicine’s current position states that a person who is training regularly- whether it be cycling, running or weights, needs 1.2-1.7g/kg of body weight each day.[1] (Remember to check here to calculate your needs.)
  • The International Society of Sports Nutrition position statement suggests 1.4–2.0 g/kg of body weight for most exercising individuals.[2]
  • This 2018 article from Nutrients suggests higher protein intakes of 2.3-3.1g/kg of body weight each day may have positive effects on body composition in resistance-trained individuals.

Help Me!! I am still Struggling to Hit My Protein Target Each Day

If you are struggling to hit your protein target each day while consuming protein-rich foods, we strongly recommend adding a recovery shake after your workouts or to start your day.

Not only is this one of the easy ways to increase dietary protein, but it’s also a tasty and convenient way to throw back a higher volume of protein on the go. If tolerated, grass-fed whey protein is our top pick. 

While protein bars can be helpful, and we have found some high protein bars with as many as 21 grams of protein in a bar, you can easily consume 30-40 grams of protein, if necessary, in a protein shake.

Need ideas for making protein shakes? Check out our 5 Tasty Weight Gain Shakes Recipes.

So, in order to get an adequate amount of protein, especially when on the go and sit-down meals are not going to occur, try to use protein bars as a snack and protein shakes as a meal.

>>>Read More: Top 17 All Natural Protein Bars

How to Choose a Protein Supplement to Help Hit Your Protein Goals

For those of you who are brand new to this topic, let’s briefly dive into the types of protein. There are a number of different protein options to choose from each day, with both animal and plant-based proteins having vocal supporters who say that they’re the best sources of protein for muscle growth.

We’re not here to change your opinion on one or the other and the best protein for YOU may depend on your gut type, DNA, food intolerances, and more.

With that said, the protein that is MOST easily absorbed and has the highest number of naturally occurring essential amino acids is whey protein. Whey protein is one of the best protein supplements to support muscle protein synthesis so you can fully recover from your workouts.

So, let’s break down the different forms of whey protein so that you don’t have to stand in an aisle of protein tubs deciphering labels for an hour. 

>>>Read More: The 17 Best Grass-Fed Whey Protein Powders

Understanding the Types of Whey Protein

This next segment of info comes from one of my most brilliant colleagues, Patrick Dixon from Momentous Nutrition. Below he provides a quick overview of the different types of whey protein currently on the market.

On this list, milk protein isolate will be the least expensive, and hydrolyzed whey protein isolate will be the most expensive. Cost is typically associated with how much work it took to create the protein. 

  1. Milk Protein Isolate:  Powder that is at least 90% protein containing both whey and casein. Milk protein isolate has a similar ratio of casein and whey protein to the ratio found naturally in milk — 80% casein to 20% whey. 
  2. Whey Protein Concentrate: The liquid remaining after the separation of casein, goes through a process called microfiltration. The whey concentrate has a protein concentration of 70-80% and still contains some lactose sugar and fat. 
  3. Whey Protein Isolate: The next level is to ultrafilter the whey protein concentrate. Minimizes the number of carbohydrates and fats, while enhancing the protein content. This type of whey contains 90%+ protein.
  4. Hydrolyzed whey protein isolate: By exposing whey protein isolate to enzymes that break the bonds holding the amino acids together, hydrolyzed whey protein is the fastest and easiest protein for digestion.

Please also keep in mind the quality and composition of your whey protein. Whey protein from grass-fed cows in New Zealand is quite different from whey protein stemming from feedlot cows in the middle of North America. The regulations are quite different, which leads to a vast difference in the quality of your protein powder.[3,4]

Regarding composition, consuming a protein powder containing probiotics in the formulation has been shown to improve digestion and absorption. If you normally take a probiotic capsule each day, take it midway through downing your protein shake. [5,6]

Time to Take Charge of Your Protein

The cornerstone to maximizing performance and health with exercise is having short recovery times. When you. can recover quicker, you have less inflammation and the ability to workout harder next time.

If you’re wondering what happens if you don’t get enough protein while working out, we hope you see beyond muscle soreness and realize that chronic low protein intake can lead to muscle atrophy and increased strain on the immune system.

If you’re wondering what happens if you lift weights but don’t eat enough protein, remember that you may have an increased risk for injury, bone loss, and additional health issues.

Protein is truly the building block of every cell in the body, especially muscle tissue. Not consuming enough to support training demands daily can leave you feeling tired, sore, and defeated. Consider taking the time today to map out your unique protein needs. Then, spend the next week tracking to see how close you are to your estimated target. We think you will be pleasantly surprised with the outcome!

If you want help figuring out your protein goals along with forming a meal plan to fix gut issues or improve performance, book a 👉free 15-minute strategy call👈 to map out a one-on-one coaching package with a member of our team.