Mom and the 'diet'

I frequently find my parents irritating and frustrating. Occasionally just plain weird. Yesterday was one of those weird days. I brought fresh lettuce from the garden. Mom handed me a tablespoon and said: "We're on a diet, so I want you to put two tablespoons of salad dressing on each salad, because two tablespoons is one serving."
Me: "You want two tablespoons of salad dressing on each salad? That's an awful lot!"
Mom: "That's how much the bottle says a serving is."
I could not choke down two tablespoons of salad dressing, I don't care what the bottle says. One teaspoon is more my size. Two tablespoons are, I notice, far more salad dressing than Mom or Dad would normally use. Even my husband, who is notorious for having a little salad with his dressing, does not use this much.
So what kind of diet is it where one has to eat more salad dressing than one normally would? Given that the dressing is the most calorific, carbohydrate containing part of the salad, which otherwise consisted of lettuce and red pepper, I can't imagine this diet is going to proove very effective. Especially as Mom says this is supposed to be a carbohydrate-limiting diet!