Would it make more sense to compare based on calories and not weight? Since you need to eat more tofu than beef for the same calorie intake. If my math is right, tofu is about 760 kcal per kg while beef is 2500 kcal per kg so that makes it ~34 grams of CO2 per kcal for beef and ~3 grams of CO2 per kcal for tofu.

Definitely tofu is still better obviously, just wanted to compare with that metric. Not sure if it makes more sense or not.