I got wondering whether this would be true when the energy of walking comes from a conventional Canadian diet, with far more calories used to produce a plate of food than the body gets out of it.
I went looking for a measurement of energy used in bike manufacturing, and came across an intriguing article(pdf) about energy use associated with electric bikes. It didn't answer my question about energy in manufacturing, since it focussed on differences between the electric bike and the human-powered bike, but it clearly illustrated the problem I was wondering about.
Despite the intuitive sense that electric bikes would require more resources than regular bikes, life-cycle analysis shows that they actually consume 2-4 times less primary energy than human riders eating a conventional diet. This conclusion is largely due to the considerable amount of transportation and processing energy that is associated with our western food system.When the analysis considered a cyclist eating local food, and electricity coming from hydro-power, the electric bike and the human-powered bike were about on par.
It's a sad commentary on our society, when you are better off letting a coal-fired plant push your bicycle than eating the food you need to spin those pedals yourself. Yet when you look at lists of "things you can do to conserve energy," how often do you see the suggestion that you plant a garden?