If we want to remove food shortages and not use up so much fossil fuels, we should just do that. There's no reason for "lowering population".
There's tons of arable land left, instead of cattle chow we could produce edible crops, farm coasts for fish, instead of mass highways, use public transportation, connect cities with it, improve upon already existing technology for both, etc.
Then again, there's tons of money in both fossil fuels and beef and we live in world with western appetite and western habits so that is not about to happen anytime soon, heh.