Fiber

• The body is not able to break down fiber. Foods high in fiber include oatmeal, beans and carrots. Even though the body cannot digest these foods, we still need them. Fiber helps regulate bowel function, which is necessary to cleanse the body. Fruits and vegetables high in fiber can take several hours to digest.
  
  

Protein

• Half of all the protein we consume is used by the body to build and repair cells. About 97 percent of the red meat we eat is easily digestible---yet, proteins stay in the stomach longer than foods that are considered less digestible, like fiber. Because of the many functions of protein in the body, it can take from one to three days to digest steak, eggs or nuts.
  
  

Fats

• Fat molecules provide a rich source of nutrients to the body. They insulate the cells, provide energy and support the immune system. Essential fats needed for a healthy diet are found in nuts and fish. Like proteins, these foods take longer to digest than those high in fiber since the body uses much of it for energy.
  
  

Carbohydrates

• Carbs contain about 40 percent of the energy needed to feed the body. Most dietary carbohydrates come from cereals, fruits and vegetables. Easily digestible, carbs takes under three hours to pass through the system.
  
  

Starch

• The body's main source of glucose, or energy, comes from starch. This includes foods like corn and potatoes. Digesting these starches could take three to four hours---which is not considered a long time when it comes to digesting food.