You do not exactly feed your physical body directly with this type of energy.Rather you pull it through your aura via energy manipulation.However if you have strong aura and natural connection to all around you ,you can easy understand why this is not necessary.You do not harm energetically things and they do not harm you when you are in balance and harmony with them.
When we eat something we absorb it's aura (chi /prana) too ,not only its physical form. The Problem with animals is that few minutes after they die their aura disperse.Plants can hold it on for some time ,which is why Eastern Cultures promote plant food as best for your energetic field and life force.
I personally had experimented with pulling and pushing energy into and out of things for many years.I noticed that plants are less harmed and especially trees.They are amazing being ,they are so connected to Earth through their roots they have the ability to recharge extremely fast.Trees also ground the negative energy we push into them fast ,while not getting negatively effected in any way.Animals and people will feel discomfort as soon as they sense ,someone is leaching their energy or as soon they feel negative force around their energetic field.
Water has a "memory" ,so it can be charged/blessed and then you can drink it.It changes it's crystal structure ,forming amazing crystals ,when charged and then frozen.
You can use Tai Chi each morning at sunrise in order to get your own chi going and in same time connect with the life force of all around you ,including the Planet Earth.In this way you feed everything and everything feeds you ,perfect circle is created ,which is always flowing and replenishing itself.
I hope you realize that we get what we put out there ,what we project that is what we get back.Harmony is not hunger or lack of something ,it is state of balance that is within and all around you.