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I see three problems with that explanation. First, I'm not sure there's a strong case that our lifestyles today are any more sedentary than in, say, the 1970s (when obesity rates were around 12% rather than 30%). We had cars, transit, elevators, escalators, school buses, television, keyboards, etc. in the 1970s, while at the same time "going to the gym" was just not something that average people did on a regular basis. Even going jogging was mildly eccentric. Second, this is looking at resting metabolic rates, not overall calorie expenditure, although there is probably some association between RMR and physical activity. Which brings me to the third point, which is that you're just shifting the burden of answering question of "why are we fat?" to "why are we sedentary?". If we are in fact increasingly sedentary, it could be that an outside factor is causing both low RMR and sedentary behavior. Anecdotally, I (as a comparatively skinny person) have a lot harder time sitting still than some of my friends and acquaintances that struggle with their weight. They might consider spending a day in bed as a great way to recharge, whereas it is something I would only do if I were pretty miserably ill. |
In 1969 48% of US kids walked to school; in 2011 it was 13%. http://guide.saferoutesinfo.org/introduction/the_decline_of_...
Public transit is actually great for walking since you are walking to and from a stop.
People have become so unused to children walking around unsupervised that it has become grounds to call child protective services.