What should i choose between nutrition and psychology?

I would suggest that you visualize which one you can see yourself doing every day. Which field will be the ones that gives you that sense of motivation, where you constantly want to learn more about and grow with it as it evolves as a field? It also depends on the level of education you plan on pursuing. As a doctoral student in Psychology, I often advise students to pursue a psychology degree If they plan on furthering their education into a master or doctoral degree in psychology; that will give you many more options in your career. Another options is as others suggested, double majoring or one being a major or minor.

P.S. Look into the field of health psychology, you may find it interesting.

As I have made decisions on what to do with my life, and what degree to major in, or what class to take I keep a few things in mind. Firstly what excites you, what interests you if you are interested in something it will make things a lot easier, putting in extra time if need be won't feel like a chore it will be fun. Next what will benefit you, if you are looking at a career in psychology and a career in nutrition, see what will offer the best lifestyle for you, with wages potential benefits. Usually after thinking about those two topics you usually have an answer, but if you still get stuck then maybe start looking at ease, and what will cause less work for you. I have always found the greatest joy in my career/college life has come doing something I am passionate in, it brings a sense of accomplishment and hope to your life when you are able to conquer tasks and make strides in something that means something to you.