HGH (human growth hormone) is the actual hormone, supplied directly
Therefore, the mechanisms of the effects of carnitine in fish should be studied
Based on reading some of the websites it seems that their hypothesis is that because ALC is involved in the Krebs cycle in the mitochondria, which gets energy from fatty acids, that means ALC helps burn fat. There is not much in the scientific literature on this topic, but I did come across an article that found no difference in metabolic parameters in study participants taking L-carnitine versus controls (not exactly the same things as acetyl-L-carnitine, but they are used somewhat similarly in the body, there just isnt the extra acetyl group in the L-carnitine)
For a deeper look at that relationship, read about the link between glutathione and sleep
Some patients notice benefits like brighter skin or improved energy within a few sessions
Many people benefit from stacking both peptides or combining ipamorelin with others like CJC-1295 for greater results