For significant weight loss and long-term maintenance, UCLA researchers assert importance of regular exercise and a healthy low-fat diet (high in fiber-rich whole foods). 
Roberts, C.K., R.J. Barnard, and D.M. Croymans. Correspondence to the Editor: Weight Loss with a Low-Carbohydrate, Mediterranean, or Low-Fat Diet. New England Journal of Medicine 

The Importance of Studying a Low-Fat Diet High In Unrefined Carbohydrates
Roberts, C.K. and R.J. Barnard. Low-carbohydrate diets as compared with low-fat diets. New Engl J Med 349:1000,2003

Low-Fat Diet High In Unrefined Carbohydrates Ameliorated Negative Effects of High Fat, Refined Carbohydrate Diet On Fat Tissue and Cholesterol Levels
Roberts, C.K., R.J. Barnard, K.H. Lui and N.D. Vaziri. Effect of diet on adipose tissue and skeletal muscle VLDL receptors and LPL: Implications for obesity and hyperlipidemia. Atherosclerosis 161:133-141,2002

A High-Fat, High Sugar Diet Increased Fat Cell Size and Induced Obesity; A Low-Fat Diet High in Unrefined Carbohydrates Did Not
Roberts, C.K., J.J. Berger and R.J. Barnard. Long-term effects of diet on leptin, energy intake and activity in a model of diet-induced obesity. J.Appl. Physiol. 93:887-893,2002

A High-Fat, High-Sugar Diet Induced Obesity and High Levels of Insulin and Homocysteine; A Low-Fat, Unrefined Carbohydrate Diet Did Not
Fonseca, V., A. Dicker-Brown, S. Ranganathan, W. Song, R.J. Barnard, L. Fink and P.A. Kern. Effect of a high-fat-sucrose diet on enzymes of homocysteine metabolism in the rat. Metabolism 49:736-741,2000

Attenuated Hormone Sensitive Lipase Activity Does Not Appear To Play a Role In the Development of Obesity
Berger, J.J. and R.J. Barnard. Effect of diet on fat cell size and hormone sensitive lipase activity. J Appl Physiol. 87:227-232,1999

The Pritikin Program Was Found To Substantially Reduce Total Cholesterol, LDL Cholesterol, Triglycerides, Glucose, Oxidation Levels, and Body Weight
Beard, C.M., R.J. Barnard, D.C. Robbins, J.M. Ordovas and E.J. Schaefer, Effects of diet and exercise on qualitative and quantitative measures of LDL and its susceptibility to oxidation. Arterioscler Thromb Vasc Biol, 16:201-207,1996

The Pritikin Program Was Found To Substantially Reduce Total Cholesterol, LDL Cholesterol, Triglycerides, Glucose, Oxidation Levels, and Body Weight
Beard, C.M., R.J. Barnard, D.C. Robbins, J.M. Ordovas and E.J. Schaefer, Effects of diet and exercise on qualitative and quantitative measures of LDL and its susceptibility to oxidation. Arterioscler Thromb Vasc Biol, 16:201-207,1996

Among 4,587 People, the Pritikin Program Was Found To Reduce Total Cholesterol On Average 23%, LDL Cholesterol 23%, and Triglycerides 33% In Three Weeks. Body Weight Was Also Significantly Reduced. Follow-Up Studies For 18 Months Showed Continued Compliance.
Barnard, R.J. Effects of life style modification on serum lipids. Arch Int Med, 151:1389-1394,1991.

The Benefits of a High-Fiber, Low-Calorie-Dense Diet Vs a High-Monounsaturated Diet For Weight Control and Prevention of Type 2 Diabetes
Kenney, J., M. Rosenthal, S. Inkeles and R.J. Barnard. Letter to the Editor. New Engl J Med , 320: 536,1989.