Get to know about all what one should do on the 5th day of dieting as well as get plans for the other days at GM Diet Facts. Fifth day would comprise of beefs and lots of tomatoes. You can call it as a feast day. An increase in the water intake will help to cleanse your system of the uric acid. Your body has been habitual of the changes in the body and you might feel lighter. You have to eat six whole tomatoes and 10 oz. Of the beef.