I've written two books on this subject after working with some of the world's obesity experts for a decade of research.
First of all, the human body is designed to fight weight loss Which is why, 98% of people put back any lost weight (and oftem more) despite what WW, JCraig and pharmaceutical companies tell you - and despite all you do to reduce food intake.
Look carefully at how they make you ashamed, blatant manipulation to make you hate your body and pay them more money. They do NOT have your best interests at heart, otherwise they'd do it for free
Fat shaming is now very much disapproved of in UK, even books are being chan1ged 
When we reduce our calories, first we lose water, then muscles and finally, fat. So initial weight loss is usually the first two.
We also alter the "set point" the level at which we can lose. So if, like me, you began at 1500 kl a day, lost a few kilos then hit a plateau (fat does not like to be lost! [smile), you reduce to 1200 - and so on.
The lowest calorie intake you get to is then your "set point" and unles you literally starve yourself (as I did 40 years ago) you won't lose 3 stone. It's that which wrecks your metabolism.
Why not aim for better health through increased nutrition ?There is no such thing as healthy food, it's how we use it which determines how healthy we are.
And keep up your walking but don't go mad with it. As long as you are active and eating well, you should feel happier knowing you are every single dieter in the world has the same problem.
And don't be fooled by the dramatic Before and After photographs, almost all eventually put back that lost weight whatever they did to keep it off.
Go to the following page, scroll down and read the short Abstract and you will see that decades ago, experts knew all this was true and tried to tell the public how harmful dieting can be.
Because the diet industry in USA alone is worth $30 billion annually, you know why they continue to lie.
www.researchgate.net/publication/223076885_Confronting_the_Failure_of_Behavioral_and_Dietary_Treatments_for_Obesity
And you may try to find a copy of "Largely Happy - changing your mind about your body" which may help you.
Kindest regards
