Low-carb diets promote restriction of carbohydrates -- your body's primary energy source -- to lose weight. While these diets may reduce your appetite and promote short term weight loss, according to MayoClinic.com, they also can cause bothersome side effects and potential health risks, depending upon what you eat and how severely you restrict carbohydrates. Before beginning a low-carb diet, seek approval and guidance from your doctor or dietitian.
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Dehydration and Weakness
Your body reaps glucose from carbohydrates in food. Every cell in your body depends upon glucose for energy. When you limit carbohydrates and your body contains too little glucose, it tries to use other substances, such as fat, for fuel. This forces your body into ketosis, an unnatural state wherein your body contains high levels of acidic substances known as ketones. Ketosis is a result of starvation, as when suffering from wasting diseases such as AIDS, tuberculosis and advance-stage eating disorders.
As your body attempts to flush excess ketones from your body, you'll likely experience a frequent need to urinate and/or increased urine volume. According to MayoClinic.com, this can trigger physical weakness and dehydration. Symptoms of dehydration include dizziness, head rushes, exhaustion, dry mouth, extreme thirst, chills, dark-colored urine, confusion and dry skin. In severe cases, dehydration causes an imbalance of the body's electrolytes, which are important bodily salts that help your muscles, heart and brain work properly.
While following a low-carb diet, you may feel emotionally deprived, since many common foods such as breads, cereal, rice, pasta, fruits and most vegetables are restricted. If your diet promotes ketosis, you may also experience emotional irritability, according to MayoClinic.com. Since carbohydrates help your body produce feel-good brain chemicals like serotonin and dopamine, you may also experience depressive moods, reduced motivation and reduced interest in activities you normally enjoy. Low-carb diets can also trigger anxiety and emotional stress, and if your weight loss is rapid or severe, may increase your risk for psychiatric disorders such as anorexia. Since carbohydrates help your brain use tryptophan -- a calmness-promoting amino acid found in some foods including chicken, turkey, beef, soybeans, shrimp and salmon -- restricting carbohydrates may also lead to sleep problems, which increases your risk for daytime exhaustion and mood swings.
Many low-carb diets allow ample intake of foods high in saturated fat and cholesterol, such as red meat, poultry fat, egg yolks, butter and high-fat cheeses. These foods, when consumed in excess, increase your risk for high cholesterol and, according to the American Heart Association, are a major risk factor for heart attack, stroke and certain forms of cancer. Low-carb diets also discourage foods that promote healthy cholesterol levels, such as whole grains, fruits and starchy vegetables.
Complex carbohydrates, such as fruits, vegetables and whole grains, are valuable sources of dietary fiber. Without sufficient fiber intake, your chance of developing constipation, gas, bloating and abdominal pain run high. Low-carb diets that promote ketosis can also trigger nausea, according to MayoClinic.com. If you resort to laxatives or fiber supplements to relieve constipation, you may experience gas and bloating as side effects or become dependent on the supplements.