Minecraft isn't difficult enough for you? If so you should try this mod which implements some food related mechanics to make your gameplay more challenging.
Recommended using along with mods providing huge food variety, such as Farmers Delight or Pam's Harvest Craft 2.
At this point there are these features:
-Dynamic food values (restored hunger depends on how much you have eaten this specific item)
-Eating speed dependency on food stats
-Well Fed effect affecting regeneration rate
-Regeneration and exhaustion rate dependency on many circumstances (currently not configurable)