A commitment device that prevents overeating is to only buy food that needs cooking (raw meat or fish, dry goods such as rice, flour, beans), and only buy drinks with zero calories. After each meal, measure out the ingredients for the next meal. The ingredients may be put into a pressure cooker, slow cooker, microwave or other gadget with a timer to cook, so the food is ready at the next mealtime, but not before. This procedure leaves no ready-to-eat food to snack on between mealtimes and no option to eat a larger portion than planned. The reason to portion out the next meal right after the previous meal is to do it while not hungry, thereby preventing oneself from increasing the portion size.
Sufficiently fast food delivery breaks the commitment, because it permits ordering a snack that arrives before the next mealtime. Such delivered food is typically processed and unhealthy. Vending machines, convenience stores, takeout restaurants or other sources of ready food in or near the building also weaken the commitment. Quarantine strengthens the commitment, reducing the temptation to go out seeking food.
Eating a balanced diet is more difficult when restricting food to only categories that need significant preparation time. Fruits and most vegetables can be eaten raw and juices give quick calories due to their high glycaemic index. Frozen fruits and vegetables are more difficult to snack on immediately, thus ease commitment without compromising health. Frozen fruit juice concentrate similarly delays gratification for at least a few minutes. Small berries thaw very quickly in water, so are a temptation.
Lifehacks to prevent overeating (from Youtube): eat in front of a mirror, avoid distractions like a computer, TV or smartphone while eating, use small dishes (Japanese style).