I have learned that I recently developed the habit of snoring. To think, people used to comment on how silently I sleep despite my big size. I don't even know why people attribute my big size to being noisy-- I'm a quiet eater, and they wonder; I'm a silent walker, and they wonder.

According to Livescience.com:

As you fall asleep, the muscles that keep your breathing passage open begin to relax, while your throat contracts. The tightening throat means a snug journey for passing air. For some people, this narrowing causes air to push forcefully through the throat, disturbing the relaxed muscle tissues in the back of the throat, causing them to vibrate. The vibrating tissue produces the sound familiarly known as snoring.

Some things that cause or even worsen snoring are things that seem to constrict the throat such as: propping your head up on too many pillows, COLDS, and, yes, obesity.
(there's my answer)

I guess the fats further tighten the air passages...