While he is correct that slow walking doesn't burn many calories in itself, there is also evidence[1] that even mild levels of exercise act to increase your metabolism significantly.
This means that the benefits outweigh the simple measurement of calories burnt, especially for people who are otherwise sedentary.
This means that the benefits outweigh the simple measurement of calories burnt, especially for people who are otherwise sedentary.
[1] http://journals.plos.org/plosone/article?id=10.1371/journal....