Did you hear the one about the guy with diabetes who had to get a signed note from his dietitian before his wife would let him have any ice cream?

Well, guess what? It's true, and it's not an isolated incident. Karen Chalmers, who is director of nutrition at Boston's Joslin Diabetes Center, sees these kinds of things all the time.

In one office visit with a couple, the husband said to her, " 'My wife eats like a cow in pasture,' " Chalmers reports. "I asked him if he'd like to sit out in the waiting room [for the remainder of the consult]. When he left, his wife confided that 'he watches everything I put in my mouth and drives me crazy.' "

Even when a loved one gets downright nasty, it is often a misguided attempt to help people stick to an eating plan that will improve their health--whether they have diabetes, heart disease, high blood pressure, obesity or any number of other conditions. The problem: It will never work because it breeds resentment. People with health problems start "reacting to the one" who's giving them a hard time, Chalmers says, "rather than thinking about their own health."

In some cases the dynamics are even more complicated, Chalmers comments, because the interference of the "food police" may be more insidious. Do you recognize yourself playing any of these parts (or being the victim of someone who plays them)?

Caretaker: "You don't have to think about anything. I have your meals all worked out, just the way the doctor said you should eat."

Martyr: "A piece of chocolate cake with icing sure would taste great for dessert, but I guess we'll just have to go with your pound cake again."

Saboteur: "Oh, come on, one brownie isn't going to kill you."

All such approaches are disrespectful, either because they take the control away from the eater or cause undue shame, guilt or pressure. That, in turn, makes eating unenjoyable, which is the worst thing that can happen, says Chalmers.

"You don't want to take away the pleasures of the table," she counsels. Even in someone with a serious medical condition for whom food choices are part of the overall treatment program, "the point is not to think of food as medication." Psychosocial pressure that takes away people's right to enjoy what they eat has been identified as one of the foremost culprits behind poor adherence to dietary plans, she notes.

People seeking to help others with food choices, Chalmers says, need to "remember that we all have to live in the real world. There are candy bars and brownies and cake in the real world. It's unrealistic to expect that those things would never be desired." Those foods can be fit in, as long as the person follows a healthful diet for the most part.

Unfortunately, there is much misinformation about the relationship of diet and disease to obscure that fact. People really do think, for instance, that people with diabetes cannot have any food with sugar. But that's not true. Even a child with diabetes who has to take insulin shots can "plan a candy bar once or twice a week," Chalmers says.

Families and friends need to learn about the particular condition of a person and put the role of diet in perspective. One husband, she says, constantly berated his wife for being obese and insisted that her weight was the reason her diabetes wasn't under control. But in fact, Chalmers points out, her diet was only a small part of her difficulty managing the disease. The woman simply "needed different medication [for the diabetes]. She wasn't ideal weight, but she was not obese by any means."

There are a number of supportive things people can do to help others enjoy their food and thereby have an easier time adjusting to dietary modifications it may be important for them to make.

* Respect privacy. You might feel perfectly comfortable talking about someone's condition to family members and friends, but "maybe the person with the condition does not want" that, Chalmers says. One couple, she recounts, went to a restaurant, and the husband "announced to the wait staff that his wife had hypertension, cardiac disease and diabetes." The wife, Chalmers notes, was perfectly capable of making appropriate dietary decisions without having the restaurant employees know her medical history.

* Don't tease. This one tends to come up when the issue is weight loss, Chalmers says. People often feel perfectly comfortable ribbing others about the need to lose weight, and the person being ribbed might accept the barbs good-naturedly but be hurting inside. No one likes to be made fun of, especially about something that is deemed so unattractive in our society.

* Act sensitively. While you don't have to eat exactly like the person who is trying to follow a pattern that will get an illness or other condition under control, you don't have to rub his or her nose in it, either. For instance, if someone has high blood pressure and loves salty snacks but has been told by the doctor to limit sodium consumption, you could probably find something to munch on other than salted nuts or pretzels.

* Remain flexible. Remember that no single food needs to be totally off limits, even for many of the more severe medical conditions. Even if someone says he's not going to eat any of a particular food and then does, it's not your place to reprimand him about it. It's his call whether he has "cheated," not yours.

* Let go. This is probably the most important advice of all--yet the hardest to follow. At the end of the day, only your loved one has control over what goes into his or her mouth. You can be supportive and accommodate the person's request to make sticking to the dietary plan easier, but the food choices ultimately made are not in your hands. Accept that, and the person who needs to make some dietary adjustments will have the best chance of being able to follow through.