Lasslo-Meeks has correctly interpreted the title; greater weight loss does follow dietary modification without exercise, and surely this is a major issue arising from contemporary public health messages concerning weight control. The current view is that somatotype and, in particular, a predisposition toward overweight are inherited ((1)Bouchard C. Despres J-.P. Mauriege P. Genetic and non-genetic determinants of regional fat distribution.Endocr Rev. 1993; 14: 72-93Google Scholar) and that physical inactivity may be the key explanatory variable responsible for its expression. Thus, a sedentary lifestyle is responsible for the population trends toward increasing obesity and is at least as important as diet—possibly the dominant etiologic factor ((2)Prentice A.M. Jebb S.A. Obesity in Britain gluttony or sloth?.BMJ. 1995; 311: 437-439Google Scholar). The Heart Foundation of Australia identified sedentary lifestyle and reduction in regular exercise as associates of the per capita weight increase throughout the past decade, a pattern similarly described in reports of increasing overweight in other populations with technological advancement ((3)Paffenbarger R.S. Hyde R.T. Wing A.L. Lee I-.M. Jung D.L. Kampert J.B. The association of changes in physical-activity level and other lifestyle characteristics with mortality among men.N Engl J Med. 1993; 328: 538-545Google Scholar). These findings are the basis of the public health messages advocating exercise for weight control. The level of exercise prescribed for the subjects in our study was similar to that described in The American Dietetic Association's position statement for physical fitness and athletic performance in adults: 20 to 30minutes of aerobic exercise 3 times per week ((4)Position of The American Dietetic Association and The Canadian Dietetic Association: nutrition for physical fitness and athletic performance for adults.J Am Diet Assoc. 1993; 93: 691-696Google Scholar).Dietitians are better equipped to counsel patients if they are aware of the comparative efficacy of diet-induced and exercise-induced weight loss Because there are conflicting views on the effectiveness of prescribing 20 to 30minutes of exercise 3 times per week for weight control, our study set out to use contemporary technology to measure changes in body composition with weight loss to compare its efficacy with weight loss induced by prudent dietary modification. Despite excellent compliance, the exercising subjects in our study felt cheated and defeated by the meager weight loss success. This level of success could have been anticipated ((5)Zelasko C.J. Exercise for weight loss what are the facts?.J Am Diet Assoc. 1995; 95: 1414-1417Google Scholar). However, we believe dietitians are better equipped to counsel patients in weight control if they are aware of the comparative efficacy of diet-induced and exercise-induced weight loss provided by this randomized, controlled study, and of the difficulties in achieving weight loss with exercise as the sole weight-controlling strategy. We agree with Lasslo-Meeks that in our study exercise appears to conserve lean mass but this is the situation in a weight loss of only 2.6kg. Whether or not lean mass can be maintained in the situation of a 6.3-kg weight loss has not been determined by this study. It may be that some loss of lean tissue is inevitable with larger weight loss with exercise of longer duration or greater frequency.