All humans have to eat food for growth and maintenance of a healthy body, but we humans have different nutrition requirements as infants, children (kids), teenagers, young adults, adults, and seniors. For example, infants may require feeding every 4 hours until they gradually age and begin to take in more solid foods. Eventually they develop into the more normal pattern of eating three times per day as young kids. However, as most parents know, kids, teenagers, and young adults often snack between meals. Snacking is often not limited to these age groups because adults and seniors often do the same.Physical activity and exercise is a major contributor to a healthy lifestyle; people are made to use their bodies, and disuse leads to unhealthy living. Unhealthy living may manifest itself in obesity, weakness, lack of endurance, and overall poor health that may foster disease development.