书接上回，今天结束第四章，从这里开始就是核心内容，为什么会饿，为什么要吃、哪些激素影响饥饿感/满足感、节食造成的激素水平异常 
FOUR: Why We Eat: How Our Appetite (and Satiety) Works

Once they have learned about the mechanisms, they can work to produce a drug to mimic the effect of bariatric surgery on appetite – and suddenly they will have a trillion-dollar product on their books. 

然后真的出来了，GLP-1神药——司美格鲁肽 

Produced by adipose (fat) tissue, leptin suppre...