Diet culture is a belief system that venerates thinness and equates health and moral virtue. For diet culture, thinness is the goal, and all behavior will be valid with the goal of achieving it.
Food only matters to the extent that it makes us gain weight, it is devoid of enjoyment and we are capable of canceling plans that we want for fear of gaining weight. Food, in addition to nourishing us, has other functions. As an emotional regulator, food releases neurotransmitters such as dopamine which make us feel good when we eat it.