Profile field selection dynamic using ajax

[Tri@de]

Id' like to make a profile field selection dynamic:
as a user select the first field, in the second field, will be different selections.
Example:

first profile field: what you eat?
selection: meat, fruit, vegetables.

second profile field: what you prefer?
Selection:
(if you selected Meat display) Hamburger, Wurstel
(if you selected fruit display) Apple, Banana
(if you selected vegetables display) Tomato, Carrot.

Comeone can help me?