I have been thinking about for a while about why-oh-why do we like food that is greasy, sweet and high in calories?
My guess (creationists would likely to contest this, but they can and will go to hell anyway) is that it has evolutionary reasons. For the survival of the species, the individual needs to survive. It needs to acquire as much of calories (energy) as possible. Therefore if we adjust this indivual to seek out the higher calories (by creating a preference for sweet=sugar (4 Cal/g), greasy=fat (9 Cal/g), umame(~meaty)=protein (4 Cal/g)). Incidentally alcohol has 7Cal/g. This is a very effective and (as any human can attest to) successful way of making sure of survival.
Also explains why all other animals like "human" food. They have the same basic needs, therefore preferences.
Now this was quite a success story in the pre-historic times, but nowadays it is becoming a survival-impeding trait. If you statisfy all of the preferences you will have a) diabetes b) generous extra weight c) heart troubles d) die early.
If evolution could keep up with these food-industrial changes, we will have humans that will no longer seek out these foods. Can you imaging not liking a good chocolate or Big Mac? Our descendents will likely to (or should) dislike these.
So it boils down to timeframe. Unfortunately evolution works on the 100K-1G year time frame, while industrial food production happened in the last 100-200 years. Quite a different scale.
This could be a case for genetic engineering, to nudge evolution along the way a little faster. Too short of a time frame can make the natural selection to fail, however. Computer simulations maybe?