Ok, let's assume that people do indeed eat too much meat and that we halve our current consumption. Population grows until it has doubled and the meat consumption is then back to the same level as to what it is now.
Eventually we can all be eating grass and rocks and there'd still be too much demand on nature crated by the existence of humans.
The only real long term solution is start limiting population growth drastically. Any crutch trying to limit energy and material consumption will not solve the root cause. (Ofc it still makes sense to cut off the excess and not be wasteful or a resource hog)
Personally I'd like to have only enough people on this planet, so that everyone can be fed and educated and have access to health care, sanitation and all the basic needs.