Quite a few studies have been done on both humans and animals accessing Guggulsterones ability to stimulate fat loss. Animal studies have shown a positive effect, and human studies have either shown a benefit or have been equivocal. Unfortunately, many of these Guggulsterons studies were inadequately controlled. A study that controlled for BMI, concurrent drug use, diet, and exercise found that people who took guggul lost 1.92 kg after 15 days compared with .32 kg in the control group.