Exhibit 3.1

CERTIFICATE OF AMENDMENT

TO

AMENDED AND RESTATED CERTIFICATE OF INCORPORATION

OF

OREXIGEN THERAPEUTICS, INC.

Orexigen Therapeutics, Inc. (the “Corporation”) originally filed its Certificate of Incorporation with the Secretary of State of Delaware on September 12, 2002, and is organized and existing under the General Corporation Law of the State of Delaware, and hereby certifies as follows:

1. The Board of Directors of the Corporation (the “Board”), acting in accordance with the provisions of Sections 141 and 242 of the DGCL, adopted resolutions amending its Amended and Restated Certificate of Incorporation, as amended (the “Certificate of Incorporation”) as follows:

THEREFORE, BE IT RESOLVED, that first paragraph of Article Fourth of the Certificate of Incorporation is hereby amended to add the following at the end of such paragraph:

“Effective at 11:59 p.m. Eastern Daylight Time on Monday, July 11, 2016 (the “Effective Time”), every ten (10) shares of the Corporation’s Common Stock, par value $0.001 per share, issued and outstanding immediately prior to the Effective Time (“Old Common Stock”) shall, automatically and without any action on the part of the Corporation or the respective holders thereof, be combined and reclassified into one (1) share of Common Stock, par value $0.001 per share, of the Corporation (“New Common Stock”). Notwithstanding the immediately preceding sentence, no fractional shares of New Common Stock shall be issued in the reclassification and, in lieu thereof, upon receipt after the Effective Time by the exchange agent selected by the Corporation of a properly completed and duly executed transmittal letter and, where shares are held in certificated form, the surrender of the stock certificate(s) formerly representing shares of Old Common Stock, any stockholder who would otherwise be entitled to a fractional share of New Common Stock as a result of the foregoing combination and reclassification of the Old Common Stock (such combination and reclassification, the “Reverse Stock Split”), following the Effective Time (after taking into account all fractional shares of New Common Stock otherwise issuable to such stockholder), shall be entitled to receive a cash payment (without interest) equal to the fractional share of New Common Stock to which such stockholder would otherwise be entitled multiplied by the average of the closing sales prices of a share of the Corporation’s Common Stock (as adjusted to give effect to the Reverse Stock Split) on The NASDAQ Global Market during regular trading hours for the five (5) consecutive trading days immediately preceding the date this Certificate of Amendment to the Restated Certificate of Incorporation is filed with the Secretary of State of the State of Delaware. Each stock certificate that, immediately prior to the Effective Time, represented shares of Old Common Stock shall, from and after the Effective Time, automatically and without any

action on the part of the Corporation or the respective holders thereof, represent that number of whole shares of New Common Stock into which the shares of Old Common Stock represented by such certificate shall have been combined and reclassified (as well as the right to receive cash in lieu of any fractional shares of New Common Stock as set forth above); provided, however, that each holder of record of a certificate that represented shares of Old Common Stock shall receive, upon surrender of such certificate, a new certificate representing the number of whole shares of New Common Stock into which the shares of Old Common Stock represented by such certificate shall have been combined and reclassified, as well as any cash in lieu of fractional shares of New Common Stock to which such holder may be entitled as set forth above.”

2. Thereafter, pursuant to a resolution of the Board, this Certificate of Amendment to Amended and Restated Certificate of Incorporation was submitted to the stockholders of the Corporation for their approval, and was duly adopted in accordance with the provisions of Section 242 of the DGCL.

IN WITNESS WHEREOF, Orexigen Therapeutics, Inc. has caused this Certificate of Amendment to Amended and Restated Certificate of Incorporation to be signed by an authorized officer thereof, this 8th day of July, 2016.

/s/ Michael Narachi

Michael Narachi

President and Chief Executive Officer