A friend of mine recently refused a dinner invitation, saying he was trying to lose weight. He explained he had just started phase one of the South Beach Diet and was being very strict about it. I offered to make a dinner that met the South Beach requirements. Turned out this meant no starchy food of any sort. I made poached cod with an Italian salsa verde. The salsa turned thin and way too tart, and at the last minute I threw in some bread to thicken it and smooth out the flavors. It was creamy and delicious. I didn’t tell my friend about the bread, but I felt guilty. Is it ever OK to feed someone a dish made with an unexpected ingredient that they wouldn’t be happy to know about? —Dissembling Host

Dear Dissembling Host,

No one wants to hear the cook say, “You’ll never guess what the secret ingredient is.” The answer is usually something you don’t want to know, like mayonnaise or Marshmallow Fluff. This Christmas, for instance, my husband received a gift of some homemade fudge. I was munching on it when he asked me to guess what made it so creamy. I stopped chewing. “Velveeta!” he announced. I immediately flew into a rage. “What kind of sick monster puts Velveeta cheese in fudge?” I screamed. (I later discovered that Kraft Foods came up with the idea.)

Actually, I quite liked the fudge. It tasted like chocolate cupcake frosting. So why was I so angry? Part of it was that I prefer to avoid highly processed foods. But the real reason for my dismay was that when you let someone feed you, it’s an act of trust, and when he or she announces there is something you don’t like in the food, you feel betrayed. You feel infantilized. You feel the way Jessica Seinfeld’s kids must feel when she reveals there are carrots and spinach in their brownies.

That said, I don’t think it’s wrong to hide ingredients in dishes, provided you’re not violating a guest’s religious or ethical beliefs or triggering potentially life-threatening allergies.

I often make penne with winter squash, sage, and brown butter for dinner companions. I’m pretty sure the health-conscious would blanch if they knew it contained a half stick of butter per serving, but I don’t feel guilty about it because everyone loves the dish. Nor should you feel guilty about compromising your friend’s South Beach Diet, even though you explicitly promised not to do so. At the last moment, you had to choose between keeping your promise and a properly emulsified and balanced sauce. You quite rightly chose the latter.

This may sound underhanded, but letting your friend or family member unwittingly consume a little bread hardly constitutes a major betrayal. When you feed someone a dish containing a hidden ingredient, whether it’s tofu or Velveeta, the person usually consumes an insignificant amount (otherwise, you wouldn’t be able to hide it). Keeping quiet about it is no worse than a white lie. As long as you’re not seriously imperiling your guests’ health, what does a little fib matter if it allows them to fully enjoy their meal?

The mistake my husband made was to tell me about the Velveeta. As soon as I learned the truth, I tried to throw the deceptive sweetmeat in the trash. He snatched it away, saying it was wrong to destroy a gift that someone had labored over. We compromised by taking it to a party that night. “Homemade?” our friends asked. “Mm-hmm,” I responded. They gobbled it up. I didn’t ask anyone to guess what made it so creamy.

Table Manners appears every Wednesday. Have a Table Manners question? Email Helena.