Every cell in your body contains protein, from your scalp to your fingernails. Your body requires a steady supply of protein to build muscles, repair damaged tissues and build cartilage. Unlike fat, which the body can store for future use, protein can't be stored. When your body is deficient in protein, there are no sources from which it can draw. Because protein is digested more slowly than carbohydrates, it gives you a steady supply of energy to perform at your best until lunch.

Your brain needs energy to function, and it receives this energy from glucose. Glucose enters the bloodstream via carbohydrates ingested in various foods. Your brain requires glucose to manufacture enzymes and neurotransmitters that are crucial to the functioning of the central nervous system. This is why it's a bad idea to skip breakfast; going for such a long period without food will cause your blood glucose level to drop, placing your body into a state of quasi-starvation. When your body is deprived of nutrients, your metabolism slows down, burning fewer calories to conserve energy, which will leave you feeling sluggish and negatively impact mental alertness. Include carbohydrates in your kid's breakfast to help him concentrate at school.

When digested, carbohydrates are converted into glucose, which is transported throughout your body via the blood and converted into energy to fuel your cells. The pancreas gland secretes a hormone called insulin, which controls the rate at which glucose enters your cells. Any excess glucose is converted to glycogen, which is then stored in the liver or in body fat. When glucose and insulin are released slowly, the result is a consistent, sustained level of energy. Complex carbohydrates take longer to process than simple carbohydrates; this is why whole-grain toast or cereal will provide a longer-lasting, sustained level of energy than sugary cereal, which produces a quick burst of energy followed by a lull.

A well-balanced breakfast should combine protein and carbohydrates with fiber and "good" fats, such as omega-3 fatty acids found in fish or fortified eggs. Healthy breakfast options include such items as whole-grain cereal with skim-milk and yogurt or French toast made from an omega-3-fortified egg and whole-wheat bread. On busy mornings when preparing breakfast presents a challenge, you can make a fruit smoothie containing mango, banana and strawberries, along with protein powder and wheat germ. Or you can make a peanut butter sandwich on whole-wheat bread to eat on the go. On more relaxed weekend mornings, whip up a batch of ranch-seasoned scrambled eggs. Serve them with whole-wheat toast and fresh fruit.