Is it the pleasure of bragging or the pain of guilt that gives our friends so much power to influence our behavior? Whichever it is, a website called Friendship Weight is ready to help you harness that pride or shame. The Atlantic reports on the site, where people track their weekly weight gains and losses, and invite carefully selected friends to admire their progress. Or not. No, actual weights need not be reported, just gains and losses. Wait, there’s more: for $9 a month, the site will send you tips and encouragement. Read more about Friendship Weight in the Atlantic.