To be perfectly honest, I've donated pretty much all of my diet books. Viva la revolution!
There's so much more to life than losing weight. There's so much more to life than obsessing over being thinner because society has told you being fat is a sin.
Plus, 'losing' weight kind of implies you'll find it again, and I think the world is finally starting to realise that's exactly what happens when you diet. You restrict, follow instruction, but it's not sustainable. There are plenty of scientific studies that have shown severe dieting is often followed by gaining back everything you lost, and then some.
MAKE SUSTAINABLE CHANGES.
Small changes over long periods of time. Don't try to change your appearance over night. And don't try to change what you look like because you think what you look like makes you less of a human being. Do it for the health benefits, the brain benefits, etc. Because I've found that reason has a lot to do with what kind of results you'll have.
As far as this book goes, it's got some interesting, basic information about counting calories etc., but as with most science, what we know is constantly evolving. Use this book as a stepping stool to find practices, foods and behaviours that work for your lifestyle, but don't treat it like a bible.
And just a final reminder: YOU ARE PERFECTLY WORTHY EXACTLY AS YOU ARE.