Cluckin’ Bell is one of the restaurants in the game, in which you can visit and order food. It is shown on your map as a chicken head. As you eat food, CJ will gain fat, which is always useful to have some. The meals you can purchase from the fast food place will give you varying amounts of fat, with the more expensive ones being more rich. To get this trophy/achievement, you only need to purchase 8 meals from the Cluckin’ Bell throughout the entirety of the game. The best thing to do is simply go here whenever you need some fat, until you unlock this, as you will always want some fat for CJ. If you don’t have fat on him, then you will lose muscle instead and you might not want that to happen.
Each meal contributes a different amount of fat to CJ, with the more expensive the meal, the more fat he will get. The $10 meal will add 3% fat to CJ, so you will know how much he gets. You can check your stats on the pause menu to see how much Fat CJ currently has. Also, if you eat too much meals at once (more than 10 within a 24 hours period), then CJ will vomit all of the food he ate, with his fat returning to its amount before you started eating that day. At the start of the game, you can head to the nearest Cluckin’ Bell and purchase eight of the cheapest meal to unlock this very easily.