Ursolic acid is a natural compound found in various plants and herbs, including apple peels, rosemary, and basil. Its use for supporting or improving fat metabolism is based on emerging scientific evidence, primarily from preclinical studies. Animal studies have shown that ursolic acid supplementation can reduce diet-induced obesity, enhance energy expenditure, increase skeletal muscle, and decrease fat mass. These effects are thought to be mediated by the activation of pathways involved in muscle growth (such as IGF-1 signaling) and increased brown fat thermogenesis, which can lead to greater calorie burning.

Human data on ursolic acid’s effects on fat metabolism are limited. Some small clinical trials and pilot studies suggest that ursolic acid may increase muscle mass and decrease body fat when combined with resistance training. However, these studies are preliminary, often with small sample sizes and short durations. The overall body of evidence supporting ursolic acid's role in fat metabolism is still developing, with most of the supportive data coming from animal models and in vitro experiments.

In summary, the use of ursolic acid to support fat metabolism is justified by early scientific investigation, but robust, large-scale clinical trials are lacking. Therefore, while there is a scientific rationale and some preliminary evidence, the strength of the evidence remains moderate to low at this time.