A healthy diet is an indispensable truth for human health. Nowadays many diseases have become -widespread for people  because of unhealthy diets. An unhealthy diet contributes to approximately 678,000 deaths each year in the U.S., due to nutrition- and obesity-related diseases such as heart disease, cancer, and type 2 diabetes. So what is healthy diet and can eating healthily prevent us from all diseases?Initially; in the past, there are diets such as Mediterranean diet, Traditional Asian diet, Scandinavian diet, which are associated with many civilizations.Even though all these diets have their own good aspects, experts say that a healthy diet means a balanced diet.Having a balanced diet means choosing from all five main food groups, in the right quantities.Secondly, is there any healthy diet to prevent all diseases? A healthy diet can prevent lots of disease but without physiological and psychological factors, only healthy eating does not work out. There is an example of that a healthy diet  would not work alone if psychological factors were ignored: Warren Buffett, one of the world’s wealthiest investors, is 84 years old.He said ‘I looked at all the research and saw the lowest mortality rate in the age group of six. So I decided to be fed like a six years old child.’ He consumes food such as potato chips and chocolate ice cream at breakfast. Buffett, also quarter of his diet is Cola, thinks that this is the most reliable way to eat. This diet, which is very dangerous for a person of 84 years under normal circumstances, has become a lifestyle for Buffett.Finally, a healthy diet needs to be completed with sports to be effective in protecting from diseases.Studies have shown that a diet without sports can provide fat balance in the body, but the physiological equilibrium of other nutrients  such as protein cannot be fully achieved.As it is understood from the first definition, diet is a part of a  balance and it is not possible to achieve this balance without any physical activities.Consequently, a healthy diet can protect us from lots of diseases  such as heart disease, cancer, and type 2 diabetes. Nevertheless, it should not be forgotten that a healthy diet should be prepared with regular physical activities and taking the physiological, psychological and social situation of the person into consideration.Diet is an inevitable part of a balance and many factors work together to achieve this balance.