Sir William Osler famously wrote: "The doctor who treats himself has a fool for a patient".
I first heard this phrase used when studying Traditional Chinese Medicine, and I heard it from more than one professor. No doubt doctors in many cultures hear something like this, and medical students are known for thinking they have the obscure diseases they're studying rather than more common conditions. They're taught "When you hear hoofbeats, think horses, not zebras" as a counter-measure to book-learned neuroses.
But we all look past the obvious, all the time, to seek something else, a diagnosis with more interest, a solution with complexity and style. I've had people who eat lots of sugar, don't sleep, and don't exercise ask me if they should buy special water to drink. I've had girls who were anxious and under eating ask if they should put even more restrictions on their diet "to be more healthy". As a college student I lost 15 pounds in several months after one of those weird juice fasts that college kids do, and then went to the GP to ask him why I'd lost my period. Duh.
Even as a nutrition nerd, or perhaps especially because of that, I've continued to have these moments of overthinking or looking past the obvious. I once asked a doctor friend why I might be feeling weird mid-morning "since I eat a good breakfast". This father of many children no doubt he took a look at me, young mother nursing an active toddler and with a 20s metabolism, and it was obvious my blood sugar was tanking 3 hours after breakfast. He asked what I was eating - eggs, toast with butter, fruit - and tallied up the calories in his head. "Not enough, you need more." he said. And that was all. There wasn't anything wrong, I didn't need supplements, I just needed to eat more given that I was underweight and nursing on demand a kid that could run. Duh again.
We all need the perspective of others, no matter how much knowledge we have. In our own heads, with our own story about what's going on, we easily lose touch with reality that would be obvious to another person, even someone with less knowledge, who asks a few reasonable questions. A good friend does this in our personal life. A nutrition coach, nurse, chiropractor or doctor does this in our health life.
As much research as I do, it's still valuable to run my plans for food, exercise, or supplements by someone else, either in a real conversation or using blog posts or books for perspective on how they've handled their own dilemmas. When I'm the one offering direction, the person asking for guidance often has a sense of what's off, and my questions illuminate the problem and direct their attention to a solution they thought was too simple to work. Another person can often see the solution to our dilemmas more clearly than we can ourselves, so even if you think you know, reach out for another opinion.