SELPLG and obesity due to melanocortin 4 receptor deficiency: In humans, several studies have shown a loss of fat [1-4], but doubts have been raised about the use of CLA for the treatment of obesity by reports that both t10, c12-CLA and c9, t11-CLA exacerbated insulin resistance in abdominally obese men [11-13], and that t10, c12- (but not c9, t11-CLA) reduced the HDL cholesterol concentration or the HDL:LDL cholesterol ratio [11,12,14].