Here is the full list of all 24 Tasty Planet achievements.
Earn gold medals on 30 levels
Eat 1,000 cats (No cats were harmed in the making of this game)
Earn a bronze medal or better on every level in the game
Eat 25,000 objects
Complete the "Cosmos" levels
Complete all levels
Earn a silver medal or higher on 30 levels
Complete the "Orbit" levels
Complete the "Sky" levels
Earn a bronze medal or higher on 30 levels
Complete the "City" levels
Complete the "Park" levels
Beat all three endurance levels
Eat 10,000 objects
Complete the "Ocean" levels
Complete the "Picnic Table" levels
Complete the "Outside" levels
Eat 5,000 objects
Eat 2,000 objects
Complete the "Laboratory" levels
Earn a silver medal or better on every level in the game
Earn gold medals on all levels
Eat 50,000 objects
Eat 100,000 objects