5 Things That Happen When You Don't Get Enough Carbs

Low-carb and keto diets are all the rage right now, but let's get one thing straight: Carbs aren't the garbage macros they're often made out to be—they're actually an important part of most diets! Let's not forget that dietary guidelines  recommend we get 45-65% of our daily calories from carbs, or about 225-325 grams in a 2,000 calorie day.

Carbs have good nutrients when they’re complex, such as fiber to fill you up, magnesium to ease sore muscles, and even some protein depending on the source (quinoa is a great example!). They come in handy for providing energy so the body and brain can function properly, and while some people do choose to limit carbs in order to burn fat instead of glucose, there’s no question that going low-carb isn’t for everyone. 

Even if you're on a ketogenic diet and lowering your net carb intake to below 50 or even 30 grams a day, chances are you will still need to consume carbs for the vitamins, minerals, fiber, and energy they provide. Think of all the superfoods you don't want to miss out on, like blueberries, avocados, and broccoli!

The main function of carbohydrates is to give you energy, which is why people often eat them before or after exercising. In particular, if your workouts require short bursts of energy, such as sprinting, you'll probably want to consume carbs beforehand so you can use that readily-available fuel instead of low-burning energy from fat. 

toast with berries and bananas

If you do decide to ditch the carbs in favor of good fat and protein, here are a few things you might expect—some changes for the better and others not so much. That’s why the “keto flu” exists when those on the diet transition from burning glucose from carbs to burning ketones from fat. If you end up loving the results, keep with it, but if it’s too much for your body, you might want to add back in some carbs to balance out your system.

What Happen if You Don't Get Enough Carbs in Your Diet? 

1. You Might Feel Weak

Without enough carbs, you could feel low in energy and experience brain fog. Since carbs provide that immediate energy from the glucose and sustainable energy (if from a healthy, complex and fibrous source), without them, energy stores will plummet. If it becomes a problem after a “keto flu” transition is over, it might be a sign that a low-carb diet just isn’t for you. However, once your body adapts to using protein and fats for fuel instead, you should be okay!

2. You Might Lose Weight

If you’re trying to lose weight, saying goodbye to carbs and keeping a limit on them will definitely help you raise your metabolism and burn more fat for fuel, thus shedding the pounds. This is especially true if you’re cutting out bad carbs, like refined grains, white flour, and sugary processed foods, as these don’t have nutritional value and can make your blood sugar levels go crazy. Plus, they often have a ton of calories, which can lead to weight gain in time.

3. Your Workouts Might Suffer

If you’ve been a HIIT junkie or are used to running miles on a treadmill, the carbohydrate deficit might make workouts more of a challenge due to lower stamina and endurance. Without enough carbs for a pre-workout snack and fuel, you might have a hard time finding the energy to get through those burpees and sprints.

woman running on treadmill

This isn’t always true, though—some people find working out on empty to be easier on their stomachs and do so regardless of low-carb or high-carb diets. So, do what’s best for you. If you find the workouts aren’t picking back up and it’s interfering with your health efforts, then bring back in some more carbs before the workouts (you can try carb cycling, for instance), and see if it helps! 

FitJoy protein bars are a great option, with plenty of protein to shape up your physique, under 10 grams of net carbs for a boost of energy, and excellent fiber for adequate digestion. Which brings us to the next point...

4. You Might be Low in Fiber or Constipated 

If you’re tossing out fruits, veggies, and grains, you could be missing out on fiber, as high-fat and high-protein foods don’t really have much. And what might happen? You could become constipated due to the low fiber intake. All that meat, fish, and cheese are great for boosting satiety, strengthening muscles, and/or keeping you trim, but they do nothing good for your bowels. If you’re having difficulties, drink lots of fluids (like water, not soda!) and take a fiber supplement. Also, add in high-fiber green veggies, which are low-carb and can still do the trick!

5. You Might Get Lightheaded

Your brain needs fuel to operate, and it’s used to getting it from glucose, so if you deprive it of its precious carbohydrates, it’ll start to get hazy and lightheaded. Let’s just say, you could be forgetting where you left your car keys or about that work deadline more often when you’re going low-carb and haven’t adjusted to the transition. 

If you find it hard to concentrate, take electrolytes to balance out the body and give it a burst of hydration and energy. Hydration directly improves cognitive function and can get rid of brain fog. Also, eat a small carb-focused snack, like a piece of dried fruit or grain-free pretzels and hummus, and see if you start thinking clearly once again.


Isadora Baum

Isadora Baum is a freelance writer, certified health coach, and author of 5-Minute Energy. She can't resist a good sample, a margarita, a new HIIT class, or an easy laugh. She writes for various magazines, such as Men's Health, Women's Health, SELF, LIVESTRONG, POPSUGAR, Allure, Health, Cooking Light, and more. Learn more about her on her website: isadorabaum.com.


related articles

    4 Tips for Finding a Personal Trainer You Like

    If you’re trying to get into a solid fitness routine but are struggling to find the types of workouts you like, the motivation to get through each session or the understanding of how to do certain exercises ...

    5 Tips for Working Out on Your Lunch Break (Without Hating Life)

    If you’re trying to get into a fitness routine but are finding it hard to squeeze in the time, take advantage of that hour lunch break in the middle of the day. Sure, it’s a little limited—you can’t necessar...

    4 Easy Tips for Reducing Sugar Intake

    ICYMI, sugar is not good for you! That’s why finding ways to reduce sugar intake in the day is so important for your health and wellbeing. If you consume excess sugar, you run the risk of increasing disease,...