S~ cientists publish their original research in scientific journals, which are fundamentally different from news magazines. The articles in scientific journals are not written by journalists – they are written by scientists. Scientific articles are not sensational stories intended to entertain the reader with an amazing discovery, nor are they news stories intended to summarize recent scientific events, nor even records of every successful and unsuccessful research venture. Instead, scientists write articles to describe their findings to the community in a transparent manner.
This passage is about how people research food, how much calories, much much energy you get from it, etc. It also explains the different kinds of food get a certain amount of calories. Some calories burn quicker than the other.