GW1516 (also known as Cardarine, Endurobol, GW501516) is not a steroid; it is a selective agonist of peroxisome proliferator-activator receptors (PPARs). It was originally developed for the treatment of obesity, diabetes mellitus, dyslipidemia, and cardiovascular diseases. GW1516 activates adenosine monophosphate-activated protein kinase (an enzyme involved in energy processes) and thus stimulates glucose uptake in skeletal muscle tissue. In studies, GW1516 demonstrated the ability to reverse the metabolic disorder in obese men with prediabetes syndrome, most likely by stimulating fatty acid oxidation. GW1516 has shown muscular protective and enhancing effects, and this seems to be related to a decrease in muscle inflammation and damage. GW1516 has been shown to elicit cardiovascular protection, possibly due to its actions in decreasing insulin spikes and stabilizing cholesterol levels. It is notable that GW1516 does not simply decrease very-low-density lipoproteins (VLDL) but also increases high-density lipoproteins (HDL), which is the result of GW1516 increasing utilization of the cholesterol transporter ABCA1. The two main uses of GW1516 in sports are to increase muscular endurance and enhance fat loss. 

Defamatory information has been associated with GW1516 from the start. The World Anti-Doping Agency (WADA) listed it as a hazardous drug, with the justification that the substance may potentially contribute to carcinogenesis. The claims of danger originate because, according to research from GlaxoSmithKline, the drug caused cancer in rats. However, in these studies, the rat subjects were administered unphysiological dosages of 10 mg/kg of body weight. Let`s draw an analogy with a human: for a 200 lb (roughly 90 kg) man, such a dose would be equal to 900 mg per day. Not only do these dosages not make sense, but they are not comparable to the normal dosage of 20 mg per day for this substance. 900 mg/day of GW1516 is comparable to taking 14625 mg of aspirin per day (while its standard single dose does not exceed 325 mg). Forget cancer; this dosage of aspirin could literally kill you! 900 mg/day of GW1516 is comparable to taking 14625 mg of aspirin per day (while its standard single dose does not exceed 325 mg). Forget cancer; this dosage of aspirin could literally kill you! 

There are two main uses of GW1516 in sports. First, it increases endurance. Test results showed an increase in endurance in rats by 68% while running on a treadmill when taking GW1516. A common dose of 10 mg/day will ensure a substantial enhancement in endurance. When used in bodybuilding, GW1516 can significantly reduce rest time between sets. The second reason to use GW1516 is fat burning. The drug has shown the ability to burn fat while still being non-catabolic, which means it helps burn fat and keep muscles. In fact, GW1516 has not shown any significant side effects. There is no hormonal suppression, no toxicity, and no other common side effects. The only thing that should be noted is that GW1516 significantly activates metabolism and contributes to the rapid consumption of glycogen during exercises; therefore, recommended dosages should not be exceeded; otherwise, signs of hypoglycemia (weakness, drowsiness, hunger, muscular cramps, and, in severe cases, loss of consciousness) may occur. If signs of hypoglycemia are felt, fast-acting simple carbohydrates should be consumed immediately.