There was a study all the way back in '92, complete with scientific shits fired.  CONCLUSIONS. The failure of some obese subjects to lose weight while eating a diet they report as low in calories is due to an energy intake substantially higher than reported and an overestimation of physical activity, not to an abnormality in thermogenesis.   http://www.nejm.org/doi/full/10.1056/NEJM199212313272701