I now have over 4 months of BodyMedia calorie burn data:

Nov 2012 Daily Average: 2,205
Dec 2012 Daily Average: 2,123
Jan 2013 Daily Average: 2,183
Feb 2013 Daily Average: 2,114

The average seems to be going down. Why?

Is this the result of changing habits, a change in seasons, or just pure dumb luck?

Ruminations on factors that could affect November calorie burn

I expect there are a lot of factors that could have affected my calorie burn in November. I suspect I got more physical activity in November. I recall it not getting exceptionally cold until December this year, so I was probably somewhat more active in November.

The BodyMedia armband I wear also acts as a pedometer, and tracked that I took more steps in Nov than in any of the other months (I also wore the device for a higher average number of hours per day, so that had some effect on the steps counted, but even taking that into account it was a bit higher).

Important learning: Overall it seems that being generally more active with moderate activity (i.e. walking instead of sitting) over more hours has a higher effect on my overall calorie burn than the number of actual exercise sessions.

Thoughts on the effects of cold on calorie burn in general

Although I generally believe that doing the same workout in the cold vs. at a normal temperature burns significantly more calories (based on research by Ray Cronise, as discussed in Wired and The Four Hour Body), cold weather overall probably has the opposite effect. Why?

I’m speculating here:

• Reduced overall activity (less going outside)
• Low percentage of time actually exposed to cold (it’s warm inside all year round)
• Marginally worse diet which may translate to slower metabolism (diet takes a dip during the holidays, and food overall is less fresh in the winter)

My next experiment:

Ultimately I’ll be able to better answer some of these questions with more data, ideally multi-year data to compare across seasons. BUT… I think I’ve come up with something that might work shorter term to find out the temperature part of the equation.

Here it is: the loop around my neighborhood is almost exactly one mile. I could jog that mile wearing pants and a T-shirt in the cold and record the time it took me to do so.

Then as we get into Spring and temperatures rise, I could jog the same mile again a number of times, each time wearing the same clothes and being careful to run the same pace (i.e. run the mile in the same amount of time), which would hopefully help to standardize the amount of “effort” I am putting in (since we want to isolate the temperature variable). I would also record the temperature during each jog.

Then I can compare my calorie burn for each run, and be much more certain about how cold is affecting it, since the other variables shouldn’t change much between trials.

Sounds like a plan.

See how my first run went in my next post.