free article in JAMA about wearables and weight loss: “Devices that monitor and provide feedback on physical activity may not offer an advantage over standard behavioral weight loss approaches.”

Effect of Wearable Technology Combined With a Lifestyle Intervention on Long-term Weight LossThe IDEA Randomized Clinical Trial  http://jama.jamanetwork.com/article.aspx?articleid=2553448 http://www.heilpraxisnet.de/naturheilpraxis/studie-fitnessarmbaender-fuehren-doch-nicht-zu-einem-zusaetzlichen-gewichtsverlust-20160922203238