This patient support community is for discussions relating to dieting, alcohol and dieting, balanced menus, diabetes, success stories, exercise, metabolism, healthy dieting, healthy snacks, holiday tips, and nutrition. Also covered are discussions relating to specific diet plans like the South Beach Diet, Atkins Diet, Slim-Fast, Weight Watchers, Counting Calories, Fat Flush, Body for Life and others.
It is not possible to survive for long on the bars/supplements that you mention. Multivitamins are not meal replacements, either.
I'm sorry I can't give you any advice beyond a caution that what you are proposing could be extremely damaging to your health, and you won't be able to live on 500 cals/day for long anyway.
If you try a reasonable diet approach, you will suceed if you follow it. There are many very affordable, easy to follow weight loss approaches available. Do not embark on the plan you are considering. Its foolish and dangerous.