If my starting weight is 276 and I lose 13lbs the first 2 week waht would the percent loss be and what is the formula?

(13 x 100) / 276 = 4.71%

4.7% divide amount of weight lost by the original weight.

Engineering answer:
Formula: loss/base weight*100
so 13/276*100 or 4.71%.
Marketing answer:
Engineering provided formula:loss/base weight*100
known wt loss: 13 lbs in 2 weeks
projected wt loss: 28.16 lbs / month
(remember there are 52 weeks in a year, but only 12 months)
round off to 29
so weight at end of 1 month = 276-29 or 247
use projected weight as base weight
so weight loss = 29/247*100 = 11.74% per month !!
Legal answer:
individual results vary

weight lost
Divided by
original weight
So for you it would be 13/276= 4.7%