Dr. Marina MacDonald holds a M.S. and PhD in nutritional sciences.  She received postdoctoral certification in metabolism and endocrinology and served as a founding fellow of the American Board of Medical Genetics.  Specializing in translational medicine, she has founded two biotechnology companies, given podium presentations at scientific conferences around the world, and authored numerous peer-reviewed articles in the fields of biochemistry, physiology, and nutrition.  It has been her lifelong goal to write a truly effective book about weight loss. 

judith A. mcmanus m.A. 

Marina macdonald M.S., PhD 

​​​​the 20 billion dollar diet 

the authors 

Judith McManus M.A. has been an educator for over 30 years, working in both the public and private sectors. Throughout her career, she has authored four books, created curriculum for over thirty courses, taught thousands of students, and been the recipient of numerous teaching awards.  After a history of yo-yo dieting, Judith took control and implemented her own healthy living strategies. With Dr. MacDonald, the authors were able to empirically support Judith's weight-loss success with scientific research. Judith's weight-loss philosophy is pretty simple: Investigate what others have done, devise a plan that' s right for you,  believe in yourself, and persevere.