The percent lost is lbs lost / initial weight. In your terms, b/a, rather
than b/a-b.
If your original weight is in A2: calculate the weight loss in b3 as
=a3-a$2, and the % loss in c3 as =b3/a$2. As you enter newer weights in
column A, just autofill the formulas from b3 and c3 into subsequent rows.

"GSTL" wrote:

ok, I admit I'm being dense.

Column A = my weight

Column b= how much I've lost

Column c= percent of body weight I've lost. therefo b/a-b

How do I put in this formula to work so that all of the rows will
automatically calculate? it seems as tough I have to list each set of cells
separatey, and since this will go over the course of the year, it will take
for ever.