;)
Low Carbs Can Cause Constipation
Fiber is an essential nutrient. It helps your digestive tract work properly. Many high fiber foods have high carbs, so when you cut carbs, you may also be seriously reducing the amount of fiber in your diet. This can lead to constipation. There are some high fiber, low-carb exceptions like certain nuts and seeds, cauliflower, broccoli, and others. If you're looking to reduce your carb intake but maintain a balanced diet, check out some of those options to help keep your digestive tract healthy.

You Might Experience Brain Fog
Having trouble remembering things? Can't focus? Cutting carbohydrates can cause brain fog and difficulty with memory recall. One study found people on low-carb diets performed worse on memory tests compared to people on a low-calorie but balanced diet. Anecdotally, people on the keto diet say this is a temporary side effect that goes once your body adapts.
Low Carb Diets Can Cause Problems with Heart Rhythm
On the more serious end of the side effect spectrum, one study found that low carb diets are strongly linked to an increased risk of atrial fibrillation, or irregular or abnormally fast heart rate. This can lead to blood clots, stroke, and heart failure.

You May Get Kidney Stones
One study found that there's a higher incidence of kidney stones among people who follow the ketogenic diet. If you have kidney problems, consult your doctor before making any major diet changes.
Bad Cholesterol Can Go Up
To replace carbohydrates, many people eat more protein and fat when following a low-carb diet. However, eating lots of protein from fatty animals can increase the LDL or bad cholesterol in the body. High cholesterol is linked to heart disease, high blood pressure, diabetes, and stroke.

Your Risk For Certain Cancers May Increase
If you're eating loads of processed meat on your low-carb diet, it can increase your risk for colorectal cancer. If you want to cut out some of the carbohydrates in your diet, make sure to eat low-carb vegetables with lots of fiber.