800 cals a day sounds like a bad idea. If you're already a stressed person, undereating is going to send your stress hormones through the roof. There are so many better options for dealing with it: don't take it out on on your body, you'll just develop an eating disorder. Seriously.
"I think the basic anti-aging diet is also the best diet for prevention and treatment of diabetes, scleroderma, and the various "connective tissue diseases." This would emphasize high protein, low unsaturated fats, low iron, and high antioxidant consumption, with a moderate or low starch consumption.
In practice, this means that a major part of the diet should be milk, cheese, eggs, shellfish, fruits and coconut oil, with vitamin E and salt as the safest supplements."
- Ray Peat