With the exception of agriculturally marginal land, using land to produce food by way of animals is typically vastly more wasteful than using it to produce human-edible food directly, certainly on a per-calorie basis. There's no shortage of studies demonstrating the potential for genuine reductions in emissions (both CO2 and CH4), and reductions in the need for land-clearing, indeed freeing up land that can reforested etc. if we didn't insist on such (land-) inefficient methods of food production. Even if the emissions-savings benefits were negligible, it's hard to thing of too other many lifestyle changes we could make that have such potential ecological benefits than moderating meat consumption. If done sensibly and thoughtfully it's almost certainly going to benefit your personal health too (and, I'd argue, your tastebuds!). But obviously there's a cultural shift involved that won't happen overnight - restaurants/food retailers in particular often seem afraid to offer any more than one or two token meat-free dishes, despite the fact that if I were to list the 10 most amazing meals I've had in recent years, maybe 1 (2 at most) would contain any meat.

> That food would also need to be grown

Animals for meet are killed before reaching adult age but it still takes longer time then one season of plant growth. They need to eat those in meantime.