How do you max your health on monster hunter freedom unite?

Answer 1

you can enlarge your health by,

eating at the kitchen that produces (health increases) results

drinking Mega Nutrients ( adds 50 to the max gauge but does not have your health full. you'll still need to dring Mega Potion or rather sleep at the base camp to achieve a max health)

drink Max Potion or Ancient Potion

Have an armor that has the "Health Increase" abilities.

Using the slots of your armor and weapons, accessorize them with Strenght Jewel until you activate the Health Increase ability. 10 points is to 20 health increase, 15 points is to 40.