What is yogurt? According to this fact sheet from Dannon,
The basic yogurt recipe is simply fresh milk, sweeteners, cultures and flavors or fruit.
Plus acesulfame K , Aspartame, cornstarch, fructose, gelatin, malic acid, pectin and/or phosphates.
According to this site, 4 oz (half of cup) of Dannon Activia yogurt contains 110 calories and 19 grams of carbohydrate, 17 of which are sugar, none of which are fiber.
Compare the yogurt to 4 oz of ready-to-eat chocolate pudding: 153 calories and 25 grams of carb, 19 of which are sugar. Except for a few extra calories (think two bites), these products are comparable.
While I'm loathe to quote doctors, one of them told me that I should take lactinex (a probiotic) while on antibiotics, and that the quantity in yogurt wasn't enough to do any good. I doubt that food that's basically pudding plus cultures makes a health food. It's more like chocolate cake for breakfast.
Want a healthier dessert for breakfast? Try making custard or flan (the night before) with a sweetener like Splenda. Custard made this way has eggs(!) and cream(!) and a fraction of the sugars, without the cornstarch, Aspartame or fructose.