When your explore * per is higher you will see chives in forest land and they are a pure agi food. There is also a fruit, red currents which is pure agi food. Try and find red current bushes. Ant larvae is another pure agi food. If you eat a mixture of rabbit, red currents and ant larvae your bar will fill with blue fairly quickly. If you can fish, try fishing until you get eels as they are another pure agi food. The wiki suggests using a feather fly but you can get eels with bait or other lures also. Also catching grasshoppers and roasting them will give you a food which is two-thirds agi.
Don't forget to make a table and chair and sit at the table and hit the feast button in order to get better value from your food.
And if you catch a couple of rabbits and dry their skins and get some string you can make bunny slippers that increase your agi and make it possible to run faster and catch more rabbits. If you are struggling to catch the rabbits remember that foxes hunt rabbits and you can sometimes get dead rabbits that a fox has just killed. You may want to chase critters like squirrels and rabbits naked except for the bunny slippers if you have been wearing nettle clothing.