On this episode of Slate Money, Felix Salmon of Fusion, Cathy O'Neil of mathbabe.org, and Slate's Moneybox columnist Jordan Weissmann are joined by special guest Elly Trickett, editor-in-chief of IBM.com and former director of content for Weight Watchers. They discuss:• How weight loss programs make money• The enduring trend of wearable fitness tech• The economics of gym memberships and yoga studiosFelix’s number: How Americans got so fat.Under Armour's new UA Record fitness app.Check out other Panoply podcasts at itunes.com/panoply.Email: slatemoney@slate.comTwitter: @Felix salmon, @mathbabedotorg, @JHWeissmannPodcast production by Zachary DinersteinSlate Money is brought to you by BollandBranch.com, the company that makes luxury bedding affordable. Get the nicest sheets you've ever owned for about half the price of what stores and boutiques are charging. Order right now and they'll give you $50 off a set of sheets, plus free shipping. Go to BollAndBranch.com and use the promo code MONEY. And by TaxAct. File simple federal and state returns for free by visiting TaxAct.com/slate. TaxAct will guide you through every step of the process — using your computer, tablet or phone — and get you the maximum refund, guaranteed. And by Credit Karma. Do not pay for your credit score! With Credit Karma, you can get your credit report, right now, absolutely free. Just visit Credit Karma.com/save to get started! There are no strings attached and no credit card is required. Learn more about your ad choices. Visit megaphone.fm/adchoices