It surely is not the case for someone going vegan or eating fast food. The only legitimate reasons to not eat meat or fast food is your own individual health, because your individual choices will only affect your individual outcomes. It's idealist to believe choosing a different source of consumption will have an impact over the industry. For instance, McDonald's main source of income is not even selling food, it's rent and royalties from franchises all over the world.

The liberal part of this idea is restricting political protest or activity to what you consume, basically transforming action into another individual form of consumerism.