[kaennar]

I've got a working theory that the problem isn't necessarily just in how we've changed eating, but in what we do in our free time.

I don't know about your parents, but when I look at what was done for free time when my grandparents(born ~1930s) and my parents (born in the 1950s) did in their free time vs what my friends and I did I can't help but see a significant difference in the time spent active. I'm not just talking about going out to ride a bike/play basketball with my friends, but later in life. When my grandfather went to work, school, and even to a bar he always walked and my father had a similar relationship with mobility during his early to teen years. Of course that changed when they both were old enough to own a car, but for both of them that wasn't until they're late teens.

Combine that with the only entertainment being other places or outside you have a populace who expends significantly more calories every day than my generation (Millenial).

As time progresses I think you might see parents from the earlier generations feeding their kids at the level they were fed as kids not recognizing that little Billy watches youtube for 3 hours after finishing his homework instead of going and playing basketball with Tuk-Tuk leading to a daily calorie surplus. Over time a daily intake of +200 calories can easily add up to a significant amount of weight.

I don't have any data to support this other than my anecdotal story and how I approached weight loss (by decreasing intake and increasing passive/everyday calory burn rate), but I think it'd be a cool thing to see studied.

[emodendroket]

You have to do a really pretty extreme amount of exercise to burn off a hamburger.

[kaennar]

You're definitely right, but 200 excess calories a day is 74,000 a year which can translate to 21 lbs a year in weight gain. It doesn't take much to get fat over a few years with a calorie surplus like that.