One big problem that the freight industry faces is that cargo has at least two dimensions – volume and weight, and there are constraints on both axes which need to be taken care of. This is the most basic model, since you can look at 3 dimensions of volume, orientation, and a host of other “dimension”.
Similarly, food also has two dimensions – volume and calories. You can either have “rich” food or you can eat lots of “normal” food. “Rich” foods include stuff like red meat, cheese, chocolate and the like.
Now the typical indian vegetarian strategy is to eat lots of low-calorie food. We eat lots of rice. Lots of rotis. We eat “pet bhar ke” (stomach full). And most of the food we eat is of the nature that if you eat until your stomach is full, you will ingest the appropriate number of calories.
So this indian vegetarian goes to London and sees people having one sandwich for lunch. It doesn’t fill his stomach, so he has two, unmindful that he is ingesting extra calories. One pasta doesn’t fill his huge tummy, so he has two. He doesn’t care for the calories he is putting on, he eats as long as his stomach feels empty.
Two months later he comes back to India with a paunch. He hasn’t been able to get rid of it even after a year.