When a person is severely obese, it means their BMI is between 35 and 40. Is there a magic formula or weight loss regimen for someone who is severely obese to reduce their weight fast? The body took its time to gain weight and hence at best the reverse can be true. Hence there is no magical weight loss formula. However if severely obese persons do the following, they can lose their weight gradually and sustain the weight loss to live healthy for the rest of their life.