the tuna is expensive+ the mercury issue. you could, if you so desired choose cooked meat. that'll be cheaper/healthier. the calories seem to be low.
what do you weigh with b.f.% and what are your goals?
you will need some fiber to push that meat through with this type of dieting. you have absolutely NONE. better to add in a couple of lettuce salads and bowls of brocolli.
that's all i got. i know slim to none about these kinds of diets. tried one once for six weeks and failed miserably.