However, if you look at the animal kingdom, you see a different story - at least, in environments where animals are allowed to live in their natural habitat and eat what they want. Most animals in their natural environment will eat what they need nutritionally at any given time.
I see this even with our chickens. For example, when it's cold out, they prefer high-calorie grains to greens and juicy vegetables. However, in the summer, they will eat all the good veggies, fruits and greens they can get! When they're molting and growing new feathers, they will gobble up extra high-protein legumes (peas and lentils) that they don't usually enjoy.
Unfortunately, as humans, we seem to have largely lost the ability to eat intuitively - although I contend that we really just need to break our addictions, and then learn to listen to our bodies again - and this episode of the Doctor's Farmacy explores this topic in more detail, as well as many more elements of how to eat for healing.