Carbohydrates:These are primarily sugars and starches and make up one of the three main nutrient categories used by the body for energy (calories). Chemically, they are neutral compounds composed of carbon, hydrogen, and oxygen. Carbohydrates exist in simple forms, like sugars, and complex forms, such as starches. The body converts most sugars and starches into glucose, a simple sugar that cells can use for energy. Complex carbohydrates originate from plants, and consuming them in place of saturated fats can help reduce blood levels. Carbohydrates are categorized into monosaccharides, disaccharides, trisaccharides, polysaccharides, and heterosaccharides. Monosaccharides, like glucose, are the smallest carbohydrates, whereas polysaccharides, such as starch, cellulose, and glycogen, can be very large and vary in length. Carbohydrates provide 4 calories per gram, which is the same as proteins. Fats are denser in energy, offering 9 calories per gram.Etymology:The term "carbohydrates" comes from the elements they contain—carbon, hydrogen, and oxygen—usually in a ratio that forms water, represented by the general formula Cn(H2O)n.

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