Disclosed is a phenyl boronic acid compound represented by Structural Formula (I): ##STR1## Ar is a substituted or unsubstituted aryl group.

• Z and Z are independently —O—. —NH— or —S—.
• X is an electron withdrawing group.
• R is a substituted or unsubstituted straight chained hydrocarbyl group optionally comprising one or more amine, ammonium, ether, thioether or phenylene linking groups and Y is —H, an amine, —[NH—(CH₂)_q]_r—NH₂, halogen, —CF₃, thiol, ammonium, alcohol, —COOH, —SO₃H, —OSO₃H or phosphonium group covalently bonded to the terminal position of R. Each —NH— in —[NH—(CH₂)_q]_r—NH₂ is optionally N-alkylated or N,N-dialkylated and —NH₂ in —[NH—(CH₂)_q]_r—NH₂ is optionally N-alkylated, N,N-dialkylated or N,N,N-trialkylated.
• q is an integer from 2 to about 10 and r is an integer from 1 to about 5.
• R₁ and R₁ are independently —H, an aliphatic group, a substituted aliphatic group, an aryl group or a substituted aryl group, or, taken together, are a C2-C5 substituted or unsubstituted alkylene group optionally comprising an amine linking group [—N⁺(R^1a)—].

  Each R₁ is Structural Formula (I) is preferably —H.

• R^1a is —H, alkyl, substituted alkyl, phenyl or substituted phenyl.

Also disclosed is a method of treating obesity in a subject by administering an effective amount of a compound represented by Structural Formula (I) and a pharmaceutical composition comprising the compound and a pharmaceutically acceptable carrier or diluent.