In Limits to Growth, a '70s era tome lauded by both environmentalists and doomsday conspiracy theorists, MIT scientists made a number of predictions about population growth, food production, etc, using the data available at the time – and were immediately lambasted by the media and politicians as being fear-mongering, since they hinted that collapse would likely come in the 2nd half of the 21st century. Recently, investment guy Joachim Klement revisited the predictions, adding data from this century. The results were… not great, with some indicating that we’re living in the peak of human development like literally right this minute.
The things is that we arriving at a limit on population growth under the current methods of production. There is a limit on how much cattle, chicken, pigs, etc we can actually raise. Now, if the whole world turned vegetarian, we probably could have much more people on earth. So much land is used to make livestock feed that could instead be used to grown actual food.