An equation published by Loftin, Waddell, Robinson, and Owens (2010) was cross-validated using ten normal-weight walkers, ten overweight walkers, and ten distance runners. Energy expenditure was measured at preferred walking (normal-weight walker and overweight walkers) or running pace (distance runners) for 5 min and corrected to a mile. Energy expenditure per mile was predicted using the Loftin et al. (2010) equation yielding a mean predicted value of 99.7 ± 13.8 kcal · mile[superscript -1]. This was significantly different (p < 0.05) than the mean actual value from the cross-validation group (107.8 ± 15.5 kcal · mile[superscript -1]), although the difference was within the published standard error of estimate. A Chow test revealed no significant differences between regression coefficients of the original equation and the cross-validation group equation. It appears the Loftin et al. (2010) regression equation is useful for exercise prescription of energy expenditure for walking or running a mile in normal-weight and overweight adults.