Expanding Waists, Decreasing Populations?
July 30th, 2007, 4 Comments »
I listened to the second half of that BBC documentary on obesity that I mentioned. It was equally fascinating, and it got me thinking about the converging problems of increasing global obesity and declining birth rates (the program didn’t cover this particular ground).
Obesity rates are predicted to increase dramatically in the developing world, and certainly aren’t declining in the developed world. As nations develop, their birth rates plummet. Many Western nations are struggling to maintain a replacement birth rate.
Fatter People, Fewer Kids
Overweight and obese women have a harder time conceiving. I went looking for a nice graph that charted increasing weight or BMI (body mass index) to declining fertility, but I came up empty. I was surprised how little hard data on this issue I could find. Either my search skills failed me or there isn’t a ton of useful studies out there to cite. I did find a 2006 article from the University of Adelaide:
“We know that obese women are 2.7 times more likely to be infertile compared to normal women. Obesity rates have doubled in Australia in the last two decades and that is the reason why a lot of women are having trouble falling pregnant or carrying babies to full term.”
Everybody agrees that obesity leads to reduced fertility, but this was the only data point I could find. Maybe Dr. Beth can help?
Compounding the issue, men who are overweight or obese have lower sperm counts and concentrations (focus, spermatozoa, focus!)–their fertility (or should that be virility?) decreases by 20 to 25%.
I wonder how an overweight and obese human race impacts longterm population projections? If we don’t live as long, have a harder time procreating and procreate less as more nations become ‘developed’, maybe we’ll reach that population peak sooner than we think?
And then start a long, slow decline? Wouldn’t that be cool if, by 3007, there were only, say, a billion people on the planet again?
