Every cell in our body requires a constant supply of energy. Carbohydrates are the most important source of fuel for the brain, heart, muscles and central nervous system. Many diets are based on low carbohydrate intake for weight loss, but the effects of such a diet are controversial. In such diets, the lack of energy is replaced by a large amount of proteins and fats. This leads to complications, diseases of the heart, gastrointestinal tract, and so on. Dietary carbohydrates are digested and broken down into glucose. Glucose is maintained in the blood as a direct source of fuel for the body. When energy requirements are met, excess glucose is stored in the liver and muscles in the form of glycogen. When carbohydrates are deficient, the liver breaks down glycogen to release glucose. Carbohydrates are classified into simple and complex.
Dairy products, fruits and vegetables are the ones that supply some vitamins, minerals, antioxidants and fiber. Refined carbohydrates and sugars, predominantly found in candies, cakes, white flour, and sugary drinks, are devoid of nutrients and—starches—are rich in vitamin A, C, E, and K, vitamin B complex, potassium, iron, and magnesium. Whole grain breads, cereals, legumes, starchy vegetables, nuts and seeds are excellent sources of complex carbohydrates that also contain fiber. A diet high in fiber prevents diabetes, constipation, obesity, and colon cancer. The minimum recommended intake of dietary carbohydrates is . Most health authorities agree that carbohydrates should be.