side effects of fast weight loss? ?

I have to loss about 30 lbs really fast. I am on a crazy and unsafe diet that i refuse to share with anyone because I don’t want anyone to damage their body as I probbaly am.
Can someone please tell me the side effects of losing weight fast?
Also what side effects are permenant?
How can I still lose weight without harming myself?

I have been on my diet for 2 weeks and I have lost 10 lbs. I plan to be on it for another 4 weeks so I can reach my goal. After that i will then begin to eat low fat, low calorie, heatly foods and then do exercies to keep from gaining weight back.

My life is important but I canot be over weight any longer. Doing it slowly makes me become inpatient. I also don’t see the results so I usually give up. I don’t want to spend 6 months to a year trying to lose what i have found that i can lose in 6 weeks.
yes
i made up my mind to stick to it

but i am asking about things that may happen so i can try to provent them yet still lose weight

so far i have learned that i can gain it back fast and that i may become dehydraited

i know how to fix the dehydration part

i’m still thinkiong on the gaining it back fact.

as far as saggy skin… I’m not losing 100 lbds, just 30 and i will be back to my normal weigth so that should be a problem

child birth is why i gained weight. with my other baby i also gained 50 pounds. I lost it all over 2 years. It has been 10 months since my last baby and i have only lost 10 pounds. that was right after giving birth. now i am stuck 40 pounds over my normal weight
i want to lose 30 pounds to look and feel better. I am tired of being so tired, week, lazy, and fat. oh, and none of my clothes fit! so this is a must

THANKS