Food is also a key component of the Purewal Memorial Cup achievement/trophy - which requires you to complete story mode whilst remaining "a sober vegan," meaning you cannot consume any alcohol, meat or dairy. The game is somewhat lenient regarding the dairy category, as it only excludes explicit dairy items like milk and doesn't count things like cakes and cookies.
This is a list of all of the food items that can be found throughout the game, how much they heal Frank and if you can eat it if you are going for the aforementioned achievement/trophy.
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Regular Food
Apple
Restores: 2 health blocks
Purewal Memorial Cup: Yes
Found: Rojo Diablo Mexican Restaurant, Chris' Fine Foods, Entertainment Isle, Rush Wireless
Bacon
Restores: 2 health blocks
Purewal Memorial Cup: No
Found: Wild West Grill House
Baked Potato
Restores: 2 health blocks
Purewal Memorial Cup: Yes
Found: Bennie Jack's BBQ Shack
Restores: 3 health blocks
Purewal Memorial Cup: No
Found: Wild West Grill House
Restores: 3 health blocks
Purewal Memorial Cup: No
Found: Bennie Jack's BBQ Shack, Wild West Grill House, Earmark Leather
Restores: 1 health block
Purewal Memorial Cup: Yes
Found: Sipparellos, Rojo Diablo Mexican Restaurant
Restores: 2 health blocks
Purewal Memorial Cup: No
Found: Various locations, especially bars and restaurants
Brownie
Restores: 1 health block
Purewal Memorial Cup: Yes
Found: The Dark Bean, Chocolate Confession, Casual Gals, Cheesecake Mania
Burrito
Restores: 2 health blocks
Purewal Memorial Cup: No
Found: Rojo Diablo Mexican Restaurant, Roy's Mart
Cake
Restores: 2 health blocks
Purewal Memorial Cup: Yes
Found: Cheesecake Mania, The Dark Bean, Yucatan Casino
Chili
Restores: 2 health blocks
Purewal Memorial Cup: No
Found: Rojo Diablo Mexican Restaurant, The Chieftain's Hut
Coffee
Restores: 1 health block
Purewal Memorial Cup: Yes
Found: Various locations, especially cafés and restaurants
Coffee Creamer
Restores: 4 health blocks
Purewal Memorial Cup: No
Found: The Dark Bean, Speedy Expresso, Roy's Mart, Wave of Style, Casual Gals, Wily Travels
Cookies
Restores: 1 health block
Purewal Memorial Cup: Yes
Found: Chocolate Confession, Cheesecake Mania, Royal Flush Plaza
Cotton Candy
Restores: 1 health block
Purewal Memorial Cup: Yes
Found: Uranus Zone
Donut
Restores: 1 health block
Purewal Memorial Cup: Yes
Found: The Dark Bean, Cheesecake Mania, Speedy Expresso
Drink Cocktail
Restores: 1 health blocks
Purewal Memorial Cup: No
Found: Sipparellos, Shoal Nightclub, Atlantica Casino, Yucatan Casino, Palisades Mall
Fish
Restores: 3 health blocks
Purewal Memorial Cup: No
Found: Atlantica Casino
Fries
Restores: 1 health block
Purewal Memorial Cup: Yes
Found: Food Court, Hamburger Fiefdom, Sturdy Package
Hamburger
Restores: 3 health blocks
Purewal Memorial Cup: No
Found: Various locations, especially restaurants
Hot Dog
Restores: 2 health blocks
Purewal Memorial Cup: No
Found: Various locations, especially restaurants and the cinema
Ice Cream
Restores: 2 health blocks
Purewal Memorial Cup: No
Found: Cheesecake Mania, Baron Von Brathaus
Jellybeans
Restores: 1 health block
Purewal Memorial Cup: Yes
Found: Chocolate Confession, Lombardi's, Astonishing Illusions, Kathy's Space
Large Soda
Restores: 1 health block
Purewal Memorial Cup: Yes
Found: Various locations, especially restaurants - can also be found in trash cans
Lobster
Restores: 6 health blocks
Purewal Memorial Cup: No
Found: Yucatan Casino's Rooftop, Cucina Donnacci, Atlantica Casino
Melon
Restores: 2 health blocks
Purewal Memorial Cup: Yes
Found: Safe House, Chris' Fine Foods, Royal Flush Plaza, Shank's
Milk
Restores: 4 health blocks
Purewal Memorial Cup: No
Found: Speedy Expresso, Chris' Fine Foods, Entertainment Isle, Platinum Strip, Safe House
Onion Rings
Restores: 1 health block
Purewal Memorial Cup: Yes
Found: Hamburger Fiefdom, Robsaka Digital, Space
Orange Juice
Restores: 4 health blocks
Purewal Memorial Cup: Yes
Found: Various locations, especially bars and restaurants
Pasta
Restores: 4 health blocks
Purewal Memorial Cup: No
Found: Antoine's, Cucina Donnacci
Pie
Restores: 1 health blocks
Purewal Memorial Cup: Yes
Found: Dining at Davey's, Food Court, Cheesecake Mania
Pineapple
Restores: 2 health blocks
Purewal Memorial Cup: Yes
Found: Chris' Fine Foods, Royal Flush Plaza, Atlantica Casino, Cucina Donnacci
Pizza
Restores: 4 health blocks
Purewal Memorial Cup: No
Found: Hungry Joe's Pizzeria, Chris' Fine Foods, Dining at Davey's, Slot Ranch Casino
Popcorn
Restores: 1 health block
Purewal Memorial Cup: Yes
Found: Paradise Platinum Screens, Uranus Zone
Pretzel
Restores: 2 health blocks
Purewal Memorial Cup: Yes
Found: Uranus Zone
Snack
Restores: 1 health block
Purewal Memorial Cup: Yes
Found: Various locations - can also be found inside trash cans
Steak
Restores: 5 health blocks
Purewal Memorial Cup: No
Found: Wild West Grill House, Bennie Jack's BBQ Shack, Baron Von Brathaus, Chris' Fine Foods
Sushi
Restores: 4 health blocks
Purewal Memorial Cup: No
Found: Luaii Wauwii
Taco
Restores: 2 health blocks
Purewal Memorial Cup: No
Found: Food Court, Rojo Diablo Mexican Restaurant
Vodka
Restores: 3 health blocks
Purewal Memorial Cup: No
Found: Modern Business Man, Slot Ranch Casino Bar, Americana Casino Bar, Shoal Nightclub
Whiskey
Restores: 3 health blocks
Purewal Memorial Cup: No
Found: Various locations, especially bars and restaurants
Wine
Restores: 5 health blocks
Purewal Memorial Cup: No
Found: Leigh's Fine Liquor, Chris' Fine Foods, Cucina Donnacci, Eternal Timepieces
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Mixed Juices
Restores: 5 health blocks (+ special effect)
Purewal Memorial Cup: Yes
Found: Made in blenders
Nectar
Restores: 5 health blocks (+ special effect)
Purewal Memorial Cup: Yes
Found: Made in blenders
Painkiller
Restores: 5 health blocks (+ special effect)
Purewal Memorial Cup: Yes
Found: Made in blenders
Quickstep
Restores: 5 health blocks (+ special effect)
Purewal Memorial Cup: Yes
Found: Made in blenders
Randomizer
Restores: 5 health blocks (+ special effect)
Purewal Memorial Cup: Yes
Found: Made in blenders
Repulse
Restores: 5 health blocks (+ special effect)
Purewal Memorial Cup: Yes
Found: Made in blenders
Spitfire
Restores: 5 health blocks (+ special effect)
Purewal Memorial Cup: Yes
Found: Made in blenders
Untouchable
Restores: 5 health blocks (+ special effect)
Purewal Memorial Cup: Yes
Found: Made in blenders
Zombait
Restores: 5 health blocks (+ special effect)
Purewal Memorial Cup: Yes
Found: Made in blenders
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Spoiled Food
Spoiled Bacon
Restores: 2 health blocks (causes vomiting)
Purewal Memorial Cup: No
Found: Trash cans
Spoiled BBQ Chicken
Restores: 2 health blocks (causes vomiting)
Purewal Memorial Cup: No
Found: Trash cans
Spoiled BBQ Ribs
Restores: 2 health blocks (causes vomiting)
Purewal Memorial Cup: No
Found: Trash cans
Spoiled Fish
Restores: 2 health blocks (causes vomiting)
Purewal Memorial Cup: No
Found: Trash cans
Spoiled Hamburger
Restores: 2 health blocks (causes vomiting)
Purewal Memorial Cup: No
Found: Trash cans
Spoiled Hot Dog
Restores: 2 health blocks (causes vomiting)
Purewal Memorial Cup: No
Found: Trash cans
Spoiled Lobster
Restores: 2 health blocks (causes vomiting)
Purewal Memorial Cup: No
Found: Trash cans
Spoiled Steak
Restores: 2 health blocks (causes vomiting)
Purewal Memorial Cup: No
Found: Trash cans
Spoiled Sushi
Restores: 2 health blocks (causes vomiting)
Purewal Memorial Cup: No
Found: Trash cans