How to get to stage 2, and 3, and 4...
First we transition into stage 2 where we no longer use even cow products and thier proteins, this can be achieved through plants, microbes and yeast style organisms to produce the main substance or protein we need. From this protein we can use also the flavors of the plants to create the perfect mesh of microbe and and plant flavors to replicate the exact textures and densities of the products we use to include even how they cook and smell.
From this stage we have begun to advance towards complete microbe biological food production and the microbes and substances created from, only the many different microbe life to produce and organize the molecules and densities to duplicate the many different textures and flavors of any known substance through synthetic organization of molecular structures and would be easily 3D printed into said forms, heated and ready to serve from the same microwave oven device I shall label the Food Replicator, it may be cooked while crafted so to speak.
Now this will be a steady and slow process as we device better ways to print this food and more efficient and effective ways to remove even plant life from our diets. During this time our bodies will begin to adapt to the sources of food and energy we produce and we will begin to become more efficient at processing those specific proteins much like the Elephants who eat grass and such. They gain huge amounts of resources from the food and they do not even process it 100%.
Now as we move from high consumption to lower consumption the body will begin to discontinue the need for such a large stomach as efficiency of this stable protein grows the body begins to absorb more energy and retain more energy from each protein considering we choose to intake, alkaline and begin to enhance bio-energy retention and transfer itself, generations of this will produce the ability to retain and store other energies such as light energy in the cells of the body, these evolutionary changed begin when the body over several generations engages the requirement for adaptation and can be done using frontal lobe choices, societies laws, structures, and the understanding of the Church and Sanctity of All Life. Technology under the Sanctity of All Life does not violate Gods Will.
(Restore a extinct species removes an immorality from God and natures hands at your creation from scratch same with victims of sexual immorality you can extract the embryo, store them for a year in the chamber project sounds of Life, Nature, and Love "No Words" Music only by "choice" while we endeavor to refine ourselves we do not command).
You could even intake a actual "battery" into the stomach where it is contained inside a material that is immune to our stomach acids and provide the same bio-energy produced from the decay of our food and exist off this alone beyond stage 4 as the cells would learn a new way to Pick-up, Package and Deliver Bio-Energy, which would remove the desire for consumption all together and this is where our evolution becomes:
High energy absorption, no mouth leading to Empathic Transfer, Large Eyes (probably black to absorb more light) for Red-Light, no butt-hole, from no solid food intake, and even the discontinued use of oxygen all together allowing life in the voids of space, completely removing the decay process allowing our bodies to exist on energies that we learned and the new ways to absorb them like, photosynthesis, frequency stimulation with vibration could stimulate inner like a bio-eardrum meets Tesla-Coil, self empowered mental energy is even a source such as LOVE.
To hold the ability to maintain that intense emotional energy is a power source itself and the body can survive on it alone, imagine a tree but the only way it has enough energy to speak to you, is if it has the love it needs to move to power it.