Current antiobesity and antidiabetic tools have been insufficient to curb these diseases and frequently cause side effects; therefore, new pancreatic lipase and α-glucosidase inhibitors could be excellent aids for the prevention and treatment of these diseases. The aim of this study was to identify, quantify, and characterize the chemical compounds with the highest degree of inhibitory activity of these enzymes, contained in a Ludwigia octovalvis hydroalcoholic extract. Chemical purification was performed by liquid-liquid separation and column chromatography. Inhibitory activities were measured in vitro, employing acarbose, orlistat, and a Camellia sinensis hydroalcoholic extract as references. For structural elucidation, Nuclear Magnetic Resonance was carried out, and High Performance Liquid Chromatography was used to quantify the compounds. For α-glucosidases, L. octovalvis hydroalcoholic extract and its ethyl acetate fraction showed half-maximal Inhibitory Concentration (IC50) values of 700 and 250 μg/mL, for lipase, 480 and 718 μg/mL, while C. sinensis showed 260 and 587 μg/mL. The most active compounds were identified as ethyl gallate (1, IC50 832 μM) and gallic acid (2, IC50 969 μM); both displayed competitive inhibition of α-glucosidases and isoorientin (3, IC50 201 μM), which displayed uncompetitive inhibition of lipase. These data could be useful in the development of a novel phytopharmaceutical drug.