Walter M. Bortz II


Q & A with Dr. Bortz
Lifelong Fitness Alliance
November 3, 2009

Q: Dear Dr. B.
After years of "Right Diet This and Right Diet That" do we at last know the best way to lose weight?

A: Your question is déjà vu over and over again. Almost 50 years ago when I was running a research lab at the Lankenau Hospital in Philadelphia supported by two million dollar NIH grants we conducted dozens of definitive experiments on just this topic. We hospitalized our overweight subjects on the Metabolic ward and fed them low calorie diets of differing compositions, using only liquid formula as food which allowed specific control of the types of diets. Importantly, we followed our patients for long 6-50 week periods.

We reported our results in the best journals, mostly the American Journal of Clinical Nutrition, JAMA, and the NEJM. Our conclusions were clear and consistent. In losing weight on a low calorie diet the only thing that matters is the number of calories, nor their type, or timing.

These results keep getting rediscovered at Harvard and Stanford and elsewhere.

A summary article is my "Predictability of Weight Loss" paper which is available on my website:

Copyright 2006-20172019 Walter M. Bortz II, M.D.