Abstract: Embodiments of the present disclosure pertain to methods of treating or preventing a condition in a subject by administering to the subject a composition having alpha-methyl-L-tryptophan. In additional embodiments, the method further includes a step of instructing the subject to administer the composition in order to treat or prevent the condition in the subject. In some embodiments, the condition includes, without limitation, hyperglycemia, diet-induced diabetes, high-fat diet-induced diabetes, insulin resistance, metabolic syndrome, extra weight, obesity, hepatic steatosis, and combinations thereof. Additional embodiments of the present disclosure pertain to compositions for use in treating or preventing a condition in a subject. In some embodiments, the composition includes alpha-methyl-L-tryptophan.