Eagle Creek

Last weekend, I went on a 3-day backpacking trip with some friends. We endured rain, snow, difficult river crossings and a vicious mouse attack, but managed to have a good time nevertheless. Here are a few pictures:

Punchbowl falls

Tunnel falls

Basalt cliffs

Apparently mice like cheese!

Vaccines

I am a label reader. Whenever I'm thinking about buying food in a box, which is rare, I typically read the whole label to look for sinister ingredients. So when I got a booster vaccine for tetanus last week, naturally I asked for the product information.

Along with a nice dose of tetanus and diphtheria toxoids, my medial deltoid received 0.28 mg of aluminum, up to 0.3 micrograms of mercury, and up to 100 micrograms of "residual formaldehyde". I got the vaccine because I like being able to chew, but I wasn't able to lift my arm for several days. I don't know if that was due to an immune response to the tetanus and diphtheria (probably) or if it was caused by the aluminum, mercury and formaldehyde they injected into my arm.

We work with formaldehyde in my lab, and I can tell you it is not to be messed with. I had to take an entire training course just to use it, during which I learned that if there's enough of it to smell, it's toxic. 0.1 parts per million in the air is enough to cause a burning sensation in the mucous membranes. We always use it in the fume hood. Formaldehyde is a toxin, a carcinogen, and a teratogen (causes birth defects). So I'm sure you'll understand why I wasn't too happy about having 100 ug of it injected into my body.

I'm not criticizing the concept of vaccines, I just wish they'd make more of an effort to clean them up!

Exercise Didn't Keep Us From Getting Fat

One of the surprising things I noticed when I was poring over data from the NHANES survey (US CDC National Health and Nutrition Examination Survey) from 1975 to 2006 is that the number of inactive people has diminished in that same time period from 50% to 24%. This is shocking to most people. We have this romanticized idea that in the 1970s people were more active, as if everyone chopped wood and walked 15 miles to work in the morning. The reality is, there were office jobs, housewives and cars without the large numbers of runners and gym-goers we have today.

Granted, NHANES data are self-reported and should be taken with a grain of salt. However, Chris at Conditioning Research pointed me to a study looking at changes in energy expenditure from the 1980s to the present in North America and Europe. It doesn't suffer from the same biases because it's based on direct measurement rather than self-reporting. Here's the executive summary: we're expending slightly more energy than we used to, partly because we exercise more and partly because it takes more energy to move our heavier bodies around.

I'm certainly not blaming the obesity problem on an increase in physical activity, but I do think we can safely rule out inactivity as the reason we've gotten fatter. In my mind, this only leaves one major possible cause for the obesity epidemic: changes in diet. Don't get me wrong, I think exercise is good. It has numerous positive effects on physical and mental health. But it's not as powerful of a tool for fat loss and general health as diet.

Anecdotally, I do know several people who lose fat when they exercise regularly. I also know some who don't lose fat when they exercise. Exercise and a healthy diet converge on some of the same metabolic pathways, such as sensitivity to insulin. But diet changes are far more effective than exercise at correcting metabolic problems. The reason is simple: the problems a person corrects with a good diet are caused by a poor diet to begin with.