If, a priori, food A and food B seem equivalent to you, and you're currently eating food A, and then you get a weak report that food B is better, then it seems like an ok decision to switch to B. If your prior belief was that food A was a little bit better, then you might switch or not depending on the exact magnitudes of "weak" and "a little bit". If your prior belief was that food A was moderately or significantly better, then the weak report would not be sufficient evidence to switch (though it could be good reason to do more research).