Obesity is also a matter of pure genetics in some cases.  I had a roommate in college -- he was 6'-2" and he weighed around 360 lbs..  Whereas I was as skinny as a rail.  My roommate ate like a bird -- one meal a day at lunchtime.  And he barely ate anything then.  He'd get a very modest amount of food on his plate, and he'd end up throwing half of that away.  He never touched things like candy bars, ice cream, cake, or other types of desserts.  At the same time, I ate like a horse.  It didn't matter how much I ate: I stayed skinny no matter what (back then -- things started to change in my late 20's ).  It wasn't unusual for my roommate to go on 2-week-long fasts, where he literally ate nothing during that entire time.  And yet he weighed what he weighed, with rolls of fat hanging off of his body.

He talked about getting "stomach stapling" surgery......I don't know if he ever did or not.  But frankly, with his already-light eating habits, I tended to question just how much good getting his stomach stapled would have done him.  Plus I've known some people to have such surgery, and then their health totally fell apart afterwards.

So it's not always eating tons of Big Macs that leads to obesity.  In spite of what often gets said: sometimes certain people just can't prevent it.  Their genetics are not kind to them.

As with so many other areas in life, when it comes to diet the keywords are "balance" and "moderation".  We aren't designed to eat grass: but neither are we strict carnivores, either.  We are omnivores, and we need a balance of foods to keep us in optimal health.  But like it or not: meat is most definitely a necessary part of a healthy diet for humans.

I recall hearing of a recent study which indicated that young children under age 3 whose parents put them on a strict vegetarian diet suffered various health & developmental problems as a result.

http://news.bbc.co.uk/1/hi/health/4282257.stm

Of course the vegans deny that it's true -- because the research results don't fit into their pre-selected ideological template: so the clear results are dismissed.

BTW - as to another topic that's been touched on in this thread: it's always good to remember that back in the days when food sources (and most everything else) truly were "natural", the average life expectancy for human beings was ~35 years.  Now that everything is loaded with chemicals, processed, and refined: life expectancies of humans are constantly going up, well beyond twice the length (and increasing) which humans 'enjoyed' while they were living in harmony with 'peaceful' (snort) nature.

When applied in the right way: technology & the mass production of food are good things.  Hmmmmm......I wonder if anyone ever suffered from salmonella back during eras when food markets consisted of totally free-range, 100% organically-grown foods with flies buzzing around them?  Maybe we can get a big government research grant to find out..........

Something To Do At 3:00AM