Unfortunately, neither of your sentences use the word "nutrition" correctly. Further to that, "nutrition", although a widely-used and understood word, tends to be used in scientific, or medical context. As such, it is rarely used in the kinds of context in which you are trying to use it.
If you must use the word "nutrition" or a form of it, here are some examples:
- I eat nutritious food.
- I follow a nutritious diet.
- I eat food with a high nutrition value.
You will notice that in all these examples, "nutritious" is a property of the food you eat and not something that describes yourself. You would rarely hear "I am well nourished" from a native English speaker as it sounds very formal and not at all like everyday speech.
A more natural, everyday way to express that you have a good diet would be, perhaps:
- I prefer healthy eating
- I eat well (although this can mean different things to different people)
- I follow a healthy diet