Influencers on social media promote them with all their might, marketing campaigns promise they’re “miracle diets,” and even studies prove the effectiveness of popular diets like the ketogenic (keto) diet and carbohydrate avoidance. So yes, the keto diet certainly has its many advantages, both for weight and for overall health—but what happens when, in such diets, you decide to completely avoid consuming carbohydrates of any kind?
Carbohydrates, just like fats and proteins, are considered a basic factor in our nutrition and are essential for energy production and a variety of biological processes. So what exactly happens when you stop giving your body its main source of energy? In short, it causes dramatic changes in the way the body functions—and they’re not always as positive as one might think.
Within 48 Hours: “Emergency Mode” and “Keto Flu”
When you stop eating carbohydrates, two main processes occur in the body at the first stage. At first, the body begins to compensate for the lack of energy through a process called gluconeogenesis—the creation of glucose from alternative sources such as amino acids from muscles and glycerol from fats. This is essentially an “emergency mode” that the body enters to maintain brain and muscle function.
Experts emphasize that although this process can be useful for short-term weight loss, the body is not meant to stay in this state for a prolonged period, as it can lead to hormonal imbalances, high blood sugar levels, and problems in the liver and thyroid gland.
The human body needs at least 130 grams of carbohydrates per day for basic functions—and more if you are physically active. Therefore, within 24 to 48 hours from the moment you stop consuming carbohydrates, the glycogen stores that the body keeps for emergencies begin to empty. To maintain brain and muscle function, the body is forced to switch to burning fat, a process called ketosis. Such a state can be accompanied by unpleasant side effects that have already been nicknamed “keto flu.”
Common side effects of this phenomenon include irritability, constipation, fatigue, and dehydration. In the long term, ketosis can also lead to electrolyte imbalances and, in extreme cases, even life-threatening conditions—especially in people with diabetes.
Lack of Nutrients and Long-Term Risks
The biggest problem with completely avoiding carbohydrates is that you don’t actually get access to essential nutrients. This danger occurs not in short-term diets but when carbohydrates are avoided for an extended period.
Avoiding carbohydrates can lead to deficiencies in vitamin C, folic acid, B vitamins, dietary fiber, and antioxidants—all the substances the body needs to function properly. For example, studies have found that athletes recovered better from workouts when they consumed carbohydrates compared to those who relied on protein alone, proving that carbohydrates are essential not only for energy but also for recovery and muscle mass gain.
In the long term, avoiding carbohydrates can also increase the risk of high cholesterol, kidney stones, weakened bones, digestive problems, and even certain types of cancer. In addition, ketogenic diets, which limit carbohydrate intake to only 50 grams per day, have not yet been sufficiently studied over the long term. Although they can definitely help people with diabetes or epilepsy in the short term, their long-term safety, over decades, is still unclear.
Do Low-Carb Diets Really Help with Weight Loss?
Low-carb diets have been a popular weight-loss strategy for decades and, as mentioned, can be beneficial for slimming down and improving health. Clinical studies do show that reducing carbohydrates contributes to weight loss and better blood sugar control in the short term, especially among people with type 2 diabetes. But these benefits usually level off within a year.
In the long term, studies show that the results of people who follow a low-carb diet versus other types of diets are more or less identical. Moreover, on a psychological level, researchers have found that low-carb diets are very restrictive and difficult to maintain over time—so most people struggle to turn them into a long-term lifestyle.
Bottom line is that instead of completely cutting carbohydrates from your diet, it’s better to focus on quality rather than quantity—try to consume complex carbohydrates such as whole grains, fruits, and vegetables. Such carbohydrates provide not only long-lasting energy but also essential fiber, vitamins, and antioxidants. It’s also important to remember that the best diet is one you can maintain over time and that gives your body everything it needs. Extremes in nutrition might bring quick results, but in the long run, they can cause more harm than good.