In cooking process as soon as heat apply to the food it starts to break down and its nutritional values are eliminated. People use to with the cooked and processed food where there is so little present of nutrition so it is not sufficient as per the body requirement.
In the processing all the nutrients in food are also degraded and more things by adding all kinds of preservatives its nutritional value gets degraded. In the processed foods, additives and other preservatives are not only reducing nutrition but it can also add more toxins in the body.