Oh boy, this is my field! Let me go do some math and I’ll get back to you in a couple hours.

EDIT: This is probably going to take a day or two. There’s a hell of a lot to break down here.

Probably a long time. Humans are fairly resilient just gotta follow the rule of 3…

3 minutes without air 3 days without water 3 weeks without food

Equals dead. (Roughly give or take depending on environmental factors.)

The whole milk is really making this plausible

http://www.milkfacts.info/Nutrition Facts/Nutrient Content.htm

Probably live for years and years. Milk is sufficient for a baby to grow up after all.

The cereal is probably going to make the milk less healthy then milk alone. Carbs, and anti nutrients, and fibre - reducing how much nutrition you can absorb from the milk

I know i would go crazy eating the same bland flakes

make it the total raisin bran variety and i could probably handle it for at least a month or two.

Long enough that it’d be hard to rule diet as your cause of death. Your biggest consequences would be low energy and a weakened immune system. Not a great place to be, but you’re not gonna be so weak that you fall over to a stiff wind. It would take an untreated illness like the flu or pneumonia to actually kill you.

Probably long enough to make yourself slightly unwell, get a test from the doctor, and sue the company for not providing you with all the nutrients they claim! Lol

Totally dont’t know

I would think for a very very long time until some vitamin deficiencies caught up to you.

It says it has all the vitamins you need but probably not all the amino acids, but idk