Phentermine functions as a catalyst for weight loss by altering brain chemistry and physiological responses:

Phentermine is a prescription medication approved by the U.S. Food and Drug Administration (FDA) for the short-term treatment of obesity. Chemically similar to amphetamines, it acts as a central nervous system stimulant and "anorectic" that triggers the body's "fight-or-flight" response to suppress appetite and increase energy expenditure. While traditionally prescribed for up to 12 weeks, emerging clinical research has begun to evaluate its safety and efficacy for longer-term use when monitored by healthcare professionals. Mechanisms of Action

Phentermine for weight loss seems safe, effective longer term