In common usage in the medical world, the phrase "n=1" is often used in the pejorative. A colleague tells you of some clinical scenario, perhaps involving some patient and their favorable response to medical intervention. You doubt the universality of the observation, so you might say "Yeah, but that's just n=1". You are trying to say that it is anecdotal. That we should be more scientific in our thinking. That n=1 is obviously not enough. It is the opposite of a large, randomized well-controlled trial.
In the "paleo" and health blogosphere, I see "N=1" experimentation, used unironically as a guiding principle, almost a fetish.
It is often explicitly stated that "how it works for you" and especially "how you feel" is the ultimate arbiter of the advisability of dietary maneuvers.
Ultimately, in the literal sense, as the LAST thing to be considered, this is true.
But the starting point should always be the soundest science - based evidence and reasoning.*
Many practicing physicians will instantly understand my skepticism, as will students of human consciousness and anyone who appreciates the radical subjectivity of human experience.
I had a patient once who claimed she was allergic to every food except skinless chicken breast and oatmeal. She ate nothing else for years.
I have had patients with back pain claim that their backs were ruined by the most trivial of events, such as lifting a 10 lb UPS package 5 years previously.
One lady claimed a large swelling on her leg occurred at a result of tripping over her cat. It turned out to be a malignant tumor.
I had a male patient present with a golfball-sized tumor his testicle, and when I told he and his young wife that it was a tumor, they both swore it had only appeared a few days ago. She was actually incensed at me, insisting that she was frequently and intimately familiar with her husbands anatomy, as there is NO WAY she would not have noticed such a thing…
One of the things I am concerned about in encouraging people to closely monitor their responses to food is creating an army of people with real but essentially psychosomatic (created by the brain) reactions to possibly harmless foods, at the same time as we are reassurring them that if they “feel fine” eating something, then that means it is harmless.
I felt absolutely fine drinking up 4 coke classics a day in my youth, no lie. I was in good shape and not obese.
Conversely, a person with undiagnosed celiac disease may have no symptoms whatsoever until they have type I diabetes, Hashomoto’s thyroiditis or neuropathy or cancer.
Might the fact that you feel so much better without something in your diet be because because of your expectations?
Both the placebo effect and its opposite, the nocebo effect are very powerful. Often more powerful than actual drugs in clinical trials where the effects can be assessed.
Why should we doubt that we can fool ourselves about just about anything?
Don't some people think they feel great on whole grains and soy and maybe even vegan fare, attributing even negative symptoms to "detox" or "candida die off" or other nonsense?
Just to be nice and sparkling clear, I am not saying one should not pay attention to how you feel with dietary changes. Far from it.
I am really just taking issue with two things:
1) Using the subjective experience as “proof” that a salutary change was made. This is especially difficult when you are changing a huge number of dietary variables at the same time and, often altering the physical culture the person experiences in big ways. Arguing that if x feels better without y is highly unreliable. In the case of both wheat and “dairy”, we should make our arguments based on plausible science first, as the “feeling” may be absent or misleading and hard to separate from the other variables in either case.
2) The contradiction between telling people to “suck it up” if they are suffering without their wheat or sugar or starches or milk, at that same time that they are being told to closely monitor how they feel as a gauge to what to eat.
It will be best to always emphasize N=1 objective measures of health like blood pressure, waist size, glucoregulation, etc.
Ultimate means last. Use N=1 subjective experience as the ultimate - last - test in this literal sense.
If you apply N=1 subjective evaluation to dietary maneuvers that were not totally grounded on science in the first place, you are liable to seriously fool yourself.
*This is really the only thing differentiating sound from unsound. The intitial science behind the dietary principle is the only differentiator. Just read 30 Bananas a Day or any vegan website to see what I mean. The subjective experience in the short term cannot be the crux. Humans can eat anything in the short term.