Carbohydrates provide more than half of the total daily calories for most Americans. Carbs supply the body with usable energy, contribute to heart, digestive, and brain health, and so much more.
While these functions of carbohydrates play an important role in health, the exact amount of carbs eaten in the diet can vary. In fact, some low-carb diets cut carbs until there are carb withdrawal symptoms.
Wondering what happens when you don’t eat enough carbs? Dive into what entails carb withdrawal symptoms and how to navigate them.
9 Things That Happen When You Don't Eat Enough Carbs
Eating a low carbohydrate diet is often considered between 50-150 grams of carbs per day. Comparatively, a typical diet with 45-65% of calories from carbohydrates can provide closer to 200- 300 grams of carbohydrates.
Cutting carbs can be popular to lose weight quickly or recommended for other medical reasons. If you are cutting carbs, the following symptoms are when there is a drastic change in consuming carbohydrates.
While these symptoms are usually temporary and not considered dangerous for most people, it is recommended to consult your doctor before starting a low-carb diet and discuss if experiencing such symptoms.
1. Energy and Blood Sugar Can Plummet
Like a car running on gasoline, the body is mostly driven by a steady flow of glucose for energy. Glucose is naturally found in carb products and stored as glycogen for backup.
Lowering or cutting out carbs can deplete the glucose supply, put the breaks on, and plummet energy levels. The body can adjust mostly to the shift in fuel sources, but low energy for exercise can be a chronic issue when cutting carbs.
2. You May have Mood Swings
Giving up those beloved carbs can cause you to feel "hangry", particularly when first cutting down your intake. And considering all the added sugar comprising an Americanized diet, forking up the comforts of chocolate chip cookies and pizza may cause people to feel moody and irritable.
However, long-term effects on mood and a low-carb diet may actually be positive according to some studies. For example, a 2020 study found following a low-carb diet was associated with less depression and anxiety. More research is needed on the long-term effects of low carb intake and mood.
3. Headaches May Appear (but Maybe Helpful to Avoid Them Long Term)
Since muscles, the heart, and the brain are reliant on glucose for energy, removing carbs forces the body to use fat as energy. This is also known as ketosis and the purpose of a ketogenic diet, is a very high-fat, low-carb diet.
Ketosis produces ketones from body fat to supply the body with usable energy. Initiating a low-carb diet and transitioning over to a ketogenic state, headaches are a common complaint. This is one, of the many, common “keto flu symptoms.”
However, for some, the headaches may go away and actually help stave off chronic headaches. A low-carb diet may be helpful in treating migraines, according to WebMD.
4. Brain Fog May Occur
Glucose from carbohydrate sources is the brain's preferred source of energy. Especially when initially reducing carb intake, the brain may feel the consequences and experience brain fog.
Another “keto flu” symptom, brain fog is fatigue of the brain that may spark mental confusion and a lack of focus.
5. You May Have Smelly Breath
On a low-carb diet, the body goes into a state of ketosis where fat is broken down to release glucose into the body. Unfortunately, ketones may cause bad breath, which bares a sweet and "fruity" smelling odor.
6. You May Have Trouble Going to the Bathroom
Not only do carb sources supply glucose, but that notorious fiber we hear about regarding digestive health. Lowering the intake of carb sources in the form of plants can naturally lower fiber and increase the risk of constipation.
To combat this, make sure to include vegetables in the diet that are low in carbs and high in fiber like leafy greens, broccoli, cucumbers, and celery. Men and women are recommended to consume 25-38 grams of fiber daily, respectively.
7. Risk for Nutritional Deficiency Can Increase
Following a long-term, low-carb diet poses the risk of nutritional deficiencies. From vitamin A found in sweet potatoes to the B vitamins found in whole grains, carb sources are loaded with vitamins and minerals necessary for vital body processes. When these foods are cut out, the risk for some nutritional deficiencies can go up.
To combat this, make sure to still include low-carb vegetables. Taking a multivitamin or other specific vitamins or minerals may be discussed with your doctor or a dietitian.
8. You Feel like You Have the Flu
Similar to the lack of energy and headaches, flu-like symptoms can be common when starting to cut carbs. In fact, some people may even experience stomach pain or nausea as an effect of a lack of carbohydrates in the body.
These flu-like symptoms can last a few days when first drastically reducing carb intake or may even last a few weeks. Cutting carbs gradually can help combat this symptom as well as staying hydrated, getting adequate electrolytes, and avoiding strenuous exercise while cutting carbs.
9. Shifts in Cholesterol Levels
Following a low-carb diet long-term could cause some good and not-so-good changes in cholesterol for some. On one hand, good HDL cholesterol can be increased with a low-carb diet. Triglycerides will also go down.
On the other hand, total cholesterol and LDL cholesterol can increase which could be a concern for heart health.
In Conclusion: Is Low-Carb Healthy?
Ultimately, the general population should aim to reduce refined carbs and focus more attention on carbs in their whole form. Cutting carbs from white bread and pasta, pastries, sugary drinks, and candies can be beneficial for everyone.
However, cutting carbs from whole grains, legumes, fruits, veggies, and dairy products can consequently cut fiber, antioxidants, vitamins, and minerals from the diet. This could lead to an increase in risk for nutritional deficiencies, constipation, or changes in cholesterol levels.
When cutting carbs from these foods, it can be natural to feel brain fog, headaches, flu-like symptoms, or lack of energy. These usually last short-term but these carb withdrawal symptoms may warrant a deeper reflection if this drastic carb cut is needed for health.
If you are wondering if a low-carb diet is right for you, talk to your doctor or consult a dietitian to discuss individual concerns or potential health benefits of following a low-carb diet.
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Daneshzad E, Keshavarz SA, Qorbani M, Larijani B, Azadbakht L. Association between a low-carbohydrate diet and sleep status, depression, anxiety, and stress score. Published February 7, 2020. https://onlinelibrary.wiley.com/doi/abs/10.1002/jsfa.10322.
Keto Diet: How it relates to Depression. WebMD. Published March 30, 2021. https://www.webmd.com/diet/what-to-know-about-keto-and-depression.
Your body on fewer carbs. WebMD. Published July 27, 2021. https://www.webmd.com/diet/ss/slideshow-what-happens-when-you-stop-eating-carbs.