Greetings dear @wuddi!
Fast food healthier, yes, more vegetables, like herbs, tomato, cucumber, less ketchup and mayonnaise. Some fresh bread or buns. That will make any fast food healthier and for people they would love to have such food. You have said this very well. In our fast food, if we use these vegetables, surely fast food can become healthy. Even if we keep our balanced diet and also eat a lot of fast food, there is no much effect on health. Good luck 😊