A reduction in appetite is never good. It ranges from a simple cold all the way to a strep throat. Sometimes, a strep throat may also be the result of gastroenteritis. Gastroenteritis is when a virus enters your stomach and causes diarrhoea as well as vomiting. It is worth note that a reduction in appetite during summer can be normal. However, feeling nauseous or detesting food can mean that you are going to have one of the illnesses listed above.