Hi,
Yes you can lose quite a lot in three days. However, my main concern it to check there is no reason why you shouldn't be doing this. Certain medications or conditions are contraindicated and even one day can make you unwell.
Also the first three days are the hardest so what happens on day 4 when you run out??
If you suffer from low blood sugar, diabetes, blood pressure, heart condition this can be extremely dangerous with correct advice...... there are more these are just examples.
If you are in perfect health and do not have any medical condition or on prescribed meds you should be okay, you must have 4 packs per day.
I strongly urge you to contact your local CDC for advice.