Tricyclic sesquiterpene lactones for use in the treatment of obesity and related diseases and non-therapeutic conditions which may be treated

A compound of the formula I, wherein the symbols are as defined in the remaining specification, or a mixture of two or more compounds of the formula I, for use as active ingredient in the therapeutic - including prophylactic - treatment of a warm-blooded animal for the regulation of body weight (preferred) and/or fat loss (preferred) and/or for the management of obesity and/or for improving the total cholesterol HDL/LDL ratio; where the compound(s) of the formula I may be present in free form, in the form of a pharmaceutically and/or nutraceutically acceptable salt, in the form of tautomers, in the form of esters and/or in the form of solvates, as well as related invention embodiments.