By not eating food that has already been bought and prepared you do not decrease demand.
Food waste in American homes is miniscule compared to the food waste in chain restaurants and fast food. You eating or not eating that steak is a mouse fart in a hurricane. There arenโt enough mice to turn this train around. Food waste needs to be tackled in a very different way than demand. A vegan restaurant is just as likely to waste food as an omnivore restaurant is.
https://www.businessinsider.com/solving-food-waste-in-americas-restaurants-2016-5