In Defense of Food (Michael Pollan)
What to Eat (Marion Nestle)
I am not sure these could be considered instructional or how-to books, but they are very informative and fascinating in terms of how we eat, what we eat, and how we fall prey to marketing, food addictions, etc. In that vein, I found them very motivational:
The End of Overeating (David Kessler)
Mindless Eating (Brian Wansink)
And now that you don't have to be perfect, you can be good.