In Wendy's Feast of Legends, characters gain bonuses for foods eaten by their players.
The game explicitly mentions that buffs stack and there are a total 6 different food items (briefly: burger, chicken, frosty, drink, fries, salad).
A particularly health-reckless power-gamer could gorge themselves on in order to gain limitless bonuses. Of course the intersection between power gamers and players of Wendy's Feast of Legends should be fairly small, but even so.
It also feels unscrupulous to deny bonuses to someone that brought their own food that doesn't fall into those categories (soup, for example), or doesn't consume certain food items (beef, for example).
How can I fairly offer buffs (and debuffs?) without directly involving player-food-consumption?