Methods for treating subjects with Prader-Willi syndrome or Smith-Magenis syndrome

A method of increasing by at least 3% the lean body mass or the lean body mass/fat mass ratio in a subject having Prader-Willi Syndrome (PWS) or Smith-Magenis syndrome (SMS), said method comprising administering once daily to said subject effective amount of a KATP channel opener, or a pharmaceutically acceptable salt thereof;

• wherein said KATP channel opener is diazoxide or a pharmaceutically acceptable salt thereof;
• wherein said KATP channel opener, or a pharmaceutically acceptable salt thereof is formulated as an oral controlled release pharmaceutical composition;
• wherein the administration of the KATP channel opener is sufficient to increase the lean body mass or lean body mass/fat mass ratio of the subject by at least 3% compared to the lean body mass or lean body mass/fat mass ratio of the subject prior to the start of the administration;
• and
• wherein the subject's circulating total cholesterol level is reduced by at least 4% after at least 10 weeks of administering the diazoxide, or a pharmaceutically acceptable salt thereof.