Sixteen years ago when I became a Registered Dietitian, a popular motto of those in my profession was "All Foods Can Fit." I found out relatively quickly that a) mottos are not necessarily based in evidence, period and b) what you learned in school does not always translate to reality either. In other words, I learned that even though TECHNICALLY people could work certain foods into their carbohydrate allowance it was better for certain people to not to eat certain foods (even when we weren't dealing with an allergy) because certain foods just caused too much of a hindrance--whether it be from a physiological standpoint (i.e. even a small amount caused elevations in blood glucose) or from a psychological standpoint (i.e. just have the oreos there causes you to think about nothing but Oreos until you eat most of the package). Now I've noticed that sixteen years later, according to the Academy of Nutrition and Dietetics (AND), this same motto or argument is appearing in a different form.
Please permit me to go anecodotal and speak from my own experience for a minute or more. I still think that technically they are correct; if I as an "authority figure" try to tell someone that this is "good" and that is "bad" or that they "can/can't" have something I will be seen as keeping them from making their own decisions. (And if you have the contrarian type of personality like Boyfriend of SkepticRD, you will eat whatever you are not supposed to just to spite the offending party). I still have a lot of patients who ask me, "can I eat that?" and my answer usually goes something like "You can eat whatever you want BUT you have to pay the consequences," or "We just talked about what carbohydrate does to your blood glucose, so what do YOU think will happen?" or "Try it and see what happens, then you decide." So, yeah, technically I'm not calling anything bad. (Unfortunately I do have some patients who are cognitively impaired, and I do have to take a yes/no approach, but that's another story).
But then there's the reality. Let's say you have a person with Type 2 diabetes, treated with just a small amount of medication at this point, and she really, really likes potatoes. She tries eating just a half a cup of potatoes, because she knows that should fit into her carbohydrate allowance, and she sees that her blood glucose is 50-100 points higher after that meal. She thinks maybe that was a fluke, and tries it again at another meal--same results. Tries it a third time, just to be sure, same results. So, now she has decided ON HER OWN, that potatoes are a "bad" food for her. Now she's coming to me for advice about what else she could eat. If I am taking the "all foods can fit approach" (and trust me, after 16 years I've seen this happen way more than I care to) I would probably give her a long speech about not being "afraid" of potatoes, the benefits of potatoes, portion size, etc. If I took a reality-based approach, I would say "good for you for figuring out what your body can and can't handle and here are some other foods you could try substuting for your carb allowance and see how they work" or "good for you, here's a recipe for cauliflower mashed potatoes that's really good" etc. Do you see the difference? The first one assumes me as an authority figure who completely ignores the work that she's done and what impacts her individually, the second approach shows how she and I work together and come up with some alternatives.
I think the other thing that AND is worried about is that by labeling certain foods as bad, or even acknowledging that some people have declared certain foods "off limits" for themselves, is that people will wind up beating themselves up when they eat a potato (or whatever it is) and just give up on the diet in general. I definitely agree the "I made one mistake so I'll just give up" approach is not exactly healthy, but that's where I get my psychology co-workers involved to help cultivate a healthier attittude. I would probably still work with that person to see if there are ways that we can safely work that food into their plan on a scheduled basis, but if that person decided that it was better for them not to have any amount of a particular food, and there really was no value to it, we would work on finding substitutes.
Another concern that is also raised is that by labeling certain foods as "bad" people will stop eating entire categories of food and wind up with nutrition deficiencies. I suppose I tend to be a little grumpy about that one since when I was a vegetarian everyone assumed I wasn't getting enough protein, and that wasn't the case, and when I went gluten free--everyone assumed I would be deficient in something, and that wasn't the case either. It does happen, like my patients who are still afraid to eat ANY fat at all because of something they heard in the 1980's, but once again, if people are counseled on healthy alternatives (or they are motivated to do the homework themselves) there's no reason that you need to wind up with a deficiency.
One of the other things that I found didn't translate so well was that people would "just" look at the carbohydrate and/or calorie content of a food and stop right there. For example, if you have a small apple or approximately two Oreo cookies, your carbohydrate content is roughly the same. The apple, however, will take longer to eat (helping you not eat as much), give you soluble fiber (pre-biotic and helps you fill up faster, so you don't eat as much), and also provides a little vitamin C and potassium, etc. The Oreos are just, well, there, not really doing anything for you. And a regular diet of no nutritional value could wind up coming back to haunt you. I have always cringed when I saw the cookies and the fruit in the same "carbohydrate exchange" category because for all practical purposes it looks like we as health care professionals are putting cookies in the same category as fruit, and not everyone takes the extra steps to figure out that it not the case. So yeah, I still have to put foods into "green light" and "red light" categories just to help people along.
Take home message--if you have decided certain foods are your "off limits" list for a legitimate reason, and those foods don't have any nutritional value anyway, then you have my full support.