In the few years the world's population could level off at around nine billion when compared to just over 7.6 billion now. According to one of the researchers Gibran Vita from Norwegian University of Science and Technology it will be difficult to feed nine billion people in the year 2050 than it would be today. For conducting the study the researchers have analyzed the changes in the populations of 186 countries between the year 1975 and 2014. One is that people on average have become taller and heavier and the second one is that the average population is getting older.