Different percentages in relation to the same number (cell)

Hi!

I really hoping someone can help me! I have looked online for an answer for an hour now.

The thing is I'm making a Spreadsheet for a weight loss course. I have everything figured out except the percentage part.

I need to have an automatic calculation which calculates the the percentage of the overall weight loss from beginning to now. It's set up so that the participants (in the weight loss program) enter their weight every day. Then i need it to calculate how big a percentages of their stating body weigt they have lost. the program is over 95 days so i need to be able to do that drag thing to duplicate the formula.

I have tried it but the it keep taking the weight from the cell above (the day before) and calculating how many percentages you have lost until now.

I really hope you can help! By all means write me if my explanation isn't sufficient.