Are low-fat diets or low-carb diets more effective for weight loss? This question was addressed in the article “Comparison of the Atkins, Zone, Ornish, and LEARN Diets for Change in Weight and Related...

Are low-fat diets or low-carb diets more effective for weight loss? This question was addressed in the article “Comparison of the Atkins, Zone, Ornish, and LEARN Diets for Change in Weight and Related Risk Factors Among Overweight Premenopausal Women: The A TO Z Weight Loss Study: A Randomized Trial” (C. Gardner, A. Kiazand, et al., Journal of the American Medical Association, 2007:969–977). A sample of 77 subjects went on a low-carbohydrate diet for six months. At the end of that time the sample mean weight loss was 4.7 kg with a sample standard deviation of 7.2 kg. A second sample of 79 subjects went on a low-fat diet. Their sample mean weight loss was 2.6 kg with a standard deviation of 5.9 kg. a) Can you conclude that the mean weight loss is greater for those on the low-carbohydrate diet? b) Can you conclude that the mean weight loss on the low-carbohydrate diet is more than 1 kg greater than that of the low-fat diet?