Growing new trees in place of old ones sustains the environment, since trees help circulate oxygen and provide homes and nutrients for animals and other plants.
Any form of mining is bad for the environment and unsustainable in the long run, garbage is the same way, and putting it on land is only slightly better, and switching to other resources doesn't do anything but burn out more resources and does nothing to sustain anything.
Fats must be broken down into fatty acids before being converted into glucose. Lipids are known as the back up energy source. They are used to make enzymes, hormones, and antibodies.
