SAN DIEGO ( TheStreet) -- The launch of Arena Pharmaceuticals' ( ARNA) obesity pill Belviq is foundering. Third quarter net sales totaled a tiny $4.8 million, well below even reduced Wall Street expectations. Early Friday morning, Eisai -- Arena's marketing partner for Belviq -- reported $9 million in Belviq net sales for the six months period ended June 30. Important to note: That's $9 million of Belviq sold over the past two quarters. Arena and Eisai announced the commercial launch of the obesity pill during the first week of June. Last August, Eisai reported second quarter Belviq net sales of $4.2 million, representing three weeks of sales in June. That means for the entire third quarter, Belviq sales totaled $4.8 million. A new drug that manages to generate just 14% sales growth over the first two quarters of its launch is on a dismal trajectory. Arena receives 31.5% royalty on Belviq net sales, so the company should report third quarter revenue of approximately $1.5 million -- well below Street consensus expectations of $5.5 million. Arena reports third-quarter results on Nov. 7. Eisai announced recently plans to double to 400 the number of U.S. sales reps marketing Belviq. Now we know why. ARNA data by YCharts -- Reported by Adam Feuerstein in Boston. Follow Adam Feuerstein on Twitter.