I'm going to hit on 2 points at once. Eating too much, and what is eaten. A lot of people eat too much because they're eating the wrong things. Your body knows what you need more than you do, so if it's craving something it neeRAB, you'll eat till your body has what it neeRAB. Another reason people eat too much, is because they eat fooRAB that don't fill. This is is one of the reasons people make a big deal of wholegrains, and unprocessed fooRAB. The biggest kicker is white breaRAB. When the flour is processed it looses it's ability to make you feel 'full'. So it takes more volume to fill you up. There a whole bunch of stuff where it's easier for your body to turn into sugar and STORE as a cute little/big pot-belly (also getting into diabetic issues) , and all that good stuff, but I'm not going to go too deep into that.
While people eat a lot, you'd be surprised how much of this population is actually malnourished. Not undernourised. We eat a lot, and it's not what we need, so we eat more to try to get what we need. It's that simple (not really, but for my point, it's simple enough)
On top of all that, turn off the **** TV and get outside, get some sunshine, go for a walk, go for a run, even sit in the park and read a book, but just lift your spirits at least. DO SOMETHING. You're attitude has a lot to do with your health. The less stressed you are, the happier you are, the more your body feels up for burning some of that energy.