Not safe. Your body needs calories, nutrients, water to survive. A simple liquid fast of water, juice could be o-k for 24 hours, but it certainly is not a method to lose "lots of weight". Please also consider the role model you may set for your family members. You selecting proper eating habits will help your family do the same.
Need supervision. Fasting to lose large amounts of weight is often hazardous. It is preferable to follow a medically-supervised protein-sparing modified fast. That way you can lose the fat without losing your muscle! you don't want to lose wt. From your heart muscle especially, it can lead to sudden death and this has happened to dieters in the past.