Here is the full list of all 30 Cat on a Diet achievements. It takes around 6-8 hours to unlock all of the achievements on Windows.
Cut 25 baskets
Change Gravity 25 times in one level
Hit Laser 50 times
Teleport 50 times
Hit 25 spikes
Unlock 80 Costumes
Complete All Bonus Levels
Complete World 4
Unlock 65 Costumes
Use Catapult 25 times
Complete World 3
Destroy 50 Uranium tiles
Collect 1024 Muffins
Unlock 50 costumes
Change Gravity 50 times
Complete World 2
Unscrew 100 screws
Travel in a basket 25 times
Collect 512 Muffins
Complete World 1
Eat 25 chewing gum
Hit the Ground 50 times
Use motor 25 times
Collect 256 Muffins
Complete a level with no Muffins collected
Slash 200 wooden tiles
Play for 10 minutes
Collect 128 Muffins
Collect 64 Muffins
Complete your first level