Carbohydrates have gotten a bad reputation, leading many to avoid them for fear of weight gain. The Institute of Medicine recommends obtaining 45 to 65 percent of your total calories from carbohydrate, which is 225 to 325 grams on a 2,000-calorie diet. While low-carb diets may produce weight loss, consuming too few carbohydrates can have negative effects on your health.
Because your body is designed to use carbohydrates as fuel, it reverts to a backup mechanism for obtaining energy when you don't eat enough carbs. The body will convert amino acids into glucose and oxidize fat to form ketone bodies, which is an alternative fuel source. This altered metabolic state is called ketosis. While ketosis does cause fat loss, it also results in water loss, which accounts for a portion of the weight loss. Prolonged ketosis leads to decreased energy levels, elevated levels of uric acid and increased risk for dehydration. In addition, the constant process of converting proteins and fat to fuel causes stress on the liver and produces excess amount of ammonia in the body.
It is possible to obtain all the necessary nutrients with a low-carb diet, but many diets that recommend slashing carbs are lacking in important vitamins and minerals. The most extreme low-carb diets, which cut out all grains, dairy and legumes and limit fruits and starchy vegetables tend to be low in vitamins A, C, B-6, thiamine, potassium, magnesium, calcium, phytonutrients and antioxidants. A study published in 2001 in the "Journal of the American Dietetic Association" found that low-carb diets tend to be significantly lower in nutrient quality than diets higher in carbohydrate content.
Constipation is Likely
Several of the most prominent sources of dietary fiber are carbohydrate-rich foods, such as whole grains, legumes and fruit. According to a review article published in the "Asia Pacific Journal of Clinical Nutrition" in 2003, strict low-carb diets tend to be low in fiber. A low intake of dietary fiber may lead to constipation. In addition, if you aren't getting the recommended 25 to 35 grams of fiber per day, you will be missing out on this nutrient's other health benefits, such as improved cardiovascular health and decreased risk for Type 2 diabetes and diverticular disease. If you are following a low-carb diet, consume plenty of nonstarchy vegetables to obtain adequate fiber.
Research on the effect of low-carb diets on physical performance have had mixed results. When carbohydrate stores are depleted and the body is forced to burn fat and protein as fuel, it leads to muscle fatigue and increased catabolism of the muscle. These factors can certainly inhibit optimal athletic performance. A review study published in "Nutrition and Metabolism" in 2004 reported that some endurance activities may be unaffected by carbohydrate restriction, but a low-carb diet will limit performance in activities such as weightlifting and sprinting. A low-carb diet is not recommended for competitive athletes.