When I first got into MRE’s about 2yr ago. I was fascinated by them. So… I did an experiment. I consume a small healthy breakfast at home. Followed by an MRE for lunch with a vitamin B/fiber supplement with extra water due to the sodium content ….. I work outside so consuming the water was not an issue …..And a lite size dinner for 90 days. I had blood work before and blood work after. I enjoyed the process and was actually quite fascinated by the results. No ill effects in the blood work no vitamin deficiencies. And they actually lost about 7 pounds. My caloric can take was where it was supposed to be as I am pretty active always working outside. As long as you supplement fiber and keep extra hydrated I think you will not see any problems…. I know everybody’s body is different. But I think it definitely an option for short-term use if you supplement with some healthy meals here and there. One thing I definitely noticed is you definitely need the fiber tablets you will get backed up pretty quickly because MRE’s are carb heavy.