In an ideal universe you could scarf carton-loads of super vanilla swirl ice cream every night after dinner without remorse. In the real world, however, there's a price to pay for such indulgence, and ice cream seems to be the worst offender in terms of calories. Is there a reason why it has to be so very fattening?
In fact, there is: it's in the amount of sugar needed to produce a specific taste. Ice cream, unlike, say, chocolate chip cookies, numbs your tongue as you eat it. This is the natural effect of applying something cold to the tongue: the more you eat, the number your tongue becomes. So, the more cold ice cream you eat, the harder it gets for your tongue to register its taste at all -- which was, presumably, why you wanted to eat it in the first place.
Producers of ice cream are aware of this restriction and counter it by a very rational method: they load enough sugar into their product to continue to produce the sensation of sweetness even after the tongue has started to become numbed by the coldness. In other words, the amount of sugar necessary to give a distinctive taste in the chocolate chip cookie is much less than that needed for the same taste in ice cream. You have to bombard your tongue with sugar in a frozen medium to make sure it can still register "sweet" the entire time you're eating.
The strategy is successful: well-made ice cream will still be yummy at the bottom of the bowl. But the price you pay is in a double-helping of sugar, which means calories -- which means fat.
