Stacking these two substances increases insulin sensitivity, fat oxidation and mitochondria synthesis according to a mice study that lasted 6 weeks. This means muscle cells burned more fat cells than they otherwise would have without stacking leucine and horny goat weed.
The human equivalent to the mice dosages are as follows.
Leucine 2 – 3 grams
Horny Goat Weed providing 20 – 30 mg of icariin