We strive for Ahimsa – harmlessness. But you must accept that it cannot be achieved.
Every act has a cost: Walking across a grassy field crushes plants and tiny insects.
All food is produced at the expense of lesser beings, though some at a much higher cost.
Only a plant can live without consuming other living things (though even some plants consume other living beings).
Even the products of plants- the fruit, the leaves, etc, are taken at some cost to other beings.
Could you live off the sap of a tree and the leaves that fall?
Perhaps, but to do so you would need to walk upon the soil. Minute creatures would still perish.
You might find it necessary to defend your food sources from the competition of parasites and pests.
You might be depriving some other species of its sustenance.
Would you allow the locusts to devour your tree? Probably not, if you wished to go on living.
So you would need to defend your source of life.
But would you spray poisons over the entire region to kill every insect? Hopefully not, for in doing so you would kill countless myriads of harmless and beneficial creatures and wipe out the food sources of all sorts of other beings.
You might decide to spray only the tree itself, thus limiting the destruction.
Or you might introduce hungry birds to the area, who naturally feed upon the insects.
Eating a diet consisting entirely of plants is ideal for your health and for the health of the planet, but it does not exempt you from contributing to the destruction of other creatures:
You cannot dig in the soil or plow a field without killing innumerable tiny creatures.
Even organic foods are produced by spraying substances on them that are toxic to insects, even if they are not synthetic chemical pesticides.
The solution cannot be to live at no cost to other beings, but rather to live in a way that does not exact a disproportionate cost to other beings.