This is one of the most common questions I am faced with in my nutrition counselling practice. It is usually asked by a client in an exasperated, overwhelmed tone of voice, accompanied by hands being thrown up in the air!
So I'm going to attempt to answer it here.
In my experience there are two levels at which you can know something to be true.
The first is to know something at the level of the intellect. This is where logic, science, traditional knowledge, past experience and “common sense” coalesce to inform and direct us.
The second is the deeper level of intuition, instinct, or “just feeling” something to be true. This more feeling-based truth happens “below the neck”, in the vast landscape of the body that lies beyond the brain. It may be described as feeling in your heart, sensing in your gut, or knowing in your bones that something is true for you.
Another way to think of it is that we have two different navigation or GPS systems that can help us to arrive at a personal truth: intellect and intuition.