Select Page

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

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

As a team of sports dietitians seeing everyone from active females to elite athletes, what 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:

“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. 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. 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 help overcome this issue.

Today we will address one of the most important questions regarding protein: What happens if you don’t get enough protein while working out?

Come on, let’s dive in!

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 sports 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 divided by 2.2 to give you kg of body weight.

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

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. 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 protein intake, especially 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?

  1. 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 in 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.

  1. 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?

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

As stated above, 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. If this becomes a chronic issue, you may also 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?

Two thoughts:

  1. 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. BUT, if your gut is so imbalanced that it is not allowing you to digest and absorb than perfectly crafted diet properly, then you will never see the progress you want to see. 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 of all time. 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 completely 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. 

  1. In our professional opinion, the protein amount that is generally recommended for athletes, especially those in strength and power sports, tends to be LESS than what these individuals actually need. 

If you lift weights regularly, 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 scroll above a bit in this article to calculate your needs.) This is pretty close to what we as dietitians learned in school.
  • Now, moving on, a position statement from the International Society of Sports Nutrition suggests 1.4–2.0 g/kg of body weight for most exercising individuals.[2] 
  • And now for the grand finale, 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, we strongly recommend adding a recovery shake after your workouts. Not only is this a convenient practice, but it’s easier to throw back a higher volume of protein on the go. If tolerated, grass-fed whey protein is one of our top picks. 

For those of you who are brand new to this topic, let’s briefly dive into the types of whey protein. While there are a number of different protein options to choose from each day  – both plant and animal-based- whey protein tends to be the fan favorite in the muscle-building sector, and for good reason. Let’s break down the different forms of whey so that you don’t have to stand in an aisle of protein tubs deciphering labels for an hour. 

Oh and if you’d like to take a quick detour, here is our article on the best plant-based protein powders and here you will find our top picks for 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 on 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

In summary, we hope you now have a better understanding of what happens if you don’t get enough protein while working out and what happens if you lift weights but don’t eat enough protein.

Protein is truly the building block of every cell in the body, especially muscle. 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!

Have any thoughts or questions about your own personal protein goal journey? Comment below. We’d love to hear from you!



About The Author

Kylene Bogden

Kylene Bogden is one of the most well respected Functional Sports Dietitians in the United States. As a high school and collegiate sprinter, she experienced recurrent injury and fatigue. After years of constant struggle, she eventually learned that an abundance of processed foods and poor fueling strategies were the root of her performance issues. Kylene's personal journey as an athlete fueled her passion for finding a more progressive approach to sports nutrition. Since then, she has helped thousands of individuals dramatically improve overall health and athletic performance by taking a whole food approach. To learn more about Kylene's story and how a functional nutrition approach can help you to achieve your goals, simply click on the contact us link in the upper right-hand corner today!

Leave a reply

Your email address will not be published. Required fields are marked *

FWDfuel 3-Day Anti-Inflammatory Meal Plan

Disclaimer: FWDfuel Sports Nutrition is a participant in the Fullscript, Amazon Services LLC, and other associates affiliate advertising programs designed to provide a means for sites to earn advertising fees by advertising and linking to their websites. As an Amazon Associate I earn from qualifying purchases.