They are learned bahaviours, deeply established and strongly influenced by culture, ethnicity, sometimes religion, even family.
More than social influences, however, emotional influences play a big role in why, when, and what we eat.
The habits of eating, cooking, and even buying food are often formed in our early adult years, and these certainly can be changed.
This change may take time, and it should. Fast diets may get results now, but it is the change in lifestyle habits which lead to genuine and long-lasting change, reaching out and into your adult years.
Usually, this change will involve:
learning about and developing healthier eating habits;
taking small but sure steps in a consistent direction;
controlling the environment and situation to reduce exposure to temptation; and
learning self-monitoring and self-management.