Friday, February 24, 2012

American Annual Food Consumption

According to a report by the USDA, Americans are eating a lot. The aggregate food supply in 2000 (the total produced and imported less exported) averaged to 3,800 calories per day per person. As I've written on, a substantial amount of this not actually eaten, but thrown away. The USDA estimates that 1100 calories per person per day are wasted, leaving 2,700 as actually consumed (recall the "based on a 2,000 calorie-diet" nutrition labels). This is 800 calories above the average in the '50s and 500 above that in the '70s. The composition has changed over time too.

We are eating a lot more oil -- 60% more than in the '50s.  An average household of four is eating 40 gallons of added oil each year, which doesn't count fats found naturally in foods such as whole meat, nuts, and dairy.
Annual consumption of added oils for a family of four.
Added sugars are also on the rise: a 40% increase over five decades.  Cane and beet sugars consumption dropped by a third, but were more than compensated by a 8-fold increase in corn syrup.  A household consumes on average 600 lb. of added sugars each year, with 22% of it from soda. This is nearly a thousand 12-oz bottles of pop.

Fruits and even vegetables are also eaten more now than in the '50s, but just by 20%.  This reflects the overall trend of more everything rather than healthier foods.  Meat consumption increased by 40%, which is driven largely by a more-than-tripling of chicken.  Each family consumes 1 + 1/3 pig and 3/5 of a cow each year, as
well as over 100 chickens.

When adding the fish to the total, each household consumes 780 lb of meat each year.  Assuming the same meat-vs-total-weight ratios of pork and beef, this corresponds to an equivalent of eight people.

As Fat Knowledge has mentioned several times, the whole Food Miles idea is overblown.  The report also shows that its cost low.  It average 4% of the total cost of the food -- the same amount as advertising.  The largest costs are labor (38%) and farm value (19%).

Wednesday, February 1, 2012

Green Stars

Go to any planetarium show and they will probably point out how some of the stars are different colors. Betelguese (Orion's shoulder) is a deep red, while Rigel (his knee) is blueish white. That's because the stars are glowing bodies that emit a distribution of radiation that more or less follows the black body curve. Cool objects like candles glow red, brighter ones like incandescent bulbs are orange-yellow, and really hot things like a welder's torch or lightning are blue-white. In fact, the colors themselves are described by the temperature (in Kelvins) of an object that would emit light of that shade. You can see in the color below the path of the black body curve.
But back to the original question? Why does it skip green?

Hotter objects emit more energy than cooler ones, and the peak frequency also increases, according to Planck's Law. So logically, at some point, the peak emission wavelength should pass through green. But as this excellent (allegedly kid-oriented) video describes, when that happens, we don't see green because of how our eyes see color.

Our eyes have three cones that detect three frequencies of light that our brain interprets as color vision. When the black bodies emit at a temperature that peaks in green, it's also sending out less (but still lots of) light at nearby frequencies (blue and red). So with all that light coming in, our brain sees the green-peaking stars as white.