Orlistat is a medication prescribed for weight management, particularly for individuals with obesity. It works within the digestive system to reduce the amount of dietary fat absorbed by the body. This lowers overall caloric intake, contributing to weight loss when combined with a reduced-calorie diet and regular physical activity.
How Orlistat Functions
Orlistat inhibits gastric and pancreatic lipases, enzymes in the stomach and small intestine that break down fats. By binding to these lipases, Orlistat inactivates them, preventing the digestion of roughly 30% of ingested dietary fat. This undigested fat passes through the digestive tract and is excreted, creating a caloric deficit. The medication primarily acts locally within the gastrointestinal tract, with minimal systemic absorption.
Prescription Weight Management Medications
Beyond Orlistat, several other prescription medications support weight management, each with distinct mechanisms. Glucagon-like peptide-1 (GLP-1) receptor agonists, such as semaglutide and liraglutide, mimic a natural hormone regulating appetite and blood sugar. These medications slow gastric emptying, prolonging fullness, and modulate brain regions controlling hunger, reducing food intake. They also enhance insulin secretion and suppress glucagon release, improving metabolic control.
Another combination medication, phentermine-topiramate, affects appetite and satiety. Phentermine suppresses hunger, while topiramate enhances fullness and suppresses appetite. This combination allows for lower doses of each component, potentially reducing side effects compared to using either drug alone.
Naltrexone-bupropion targets brain pathways involved in hunger and reward. Bupropion, an antidepressant, stimulates neurons in the hypothalamus that promote appetite suppression and increased energy expenditure. Naltrexone, an opioid antagonist, blocks an inhibitory feedback loop, augmenting bupropion’s effect and potentially reducing food cravings. These prescription medications require medical oversight due to their specific mechanisms and potential side effects.
Non-Prescription and Herbal Weight Loss Options
Many over-the-counter supplements and herbal remedies are marketed for weight loss. Fiber-based supplements like glucomannan, derived from the konjac plant, absorb water in the stomach to create fullness, potentially reducing food intake. This viscous fiber can also delay stomach emptying and may reduce the absorption of fats and proteins, contributing to a caloric deficit. Chitosan, sourced from crustacean shells, is another fiber promoted to bind with dietary fats in the digestive tract, theoretically preventing their absorption. It forms a gel-like substance in the stomach that binds to fat molecules and bile acids, leading to their excretion.
Stimulants like caffeine and green tea extract are popular for their purported weight loss benefits. Caffeine can increase metabolism and suppress appetite by stimulating the central nervous system, leading to increased fat oxidation and calorie burning. Green tea extract, particularly its catechins like epigallocatechin gallate (EGCG), may enhance fat oxidation and boost metabolism. EGCG is believed to inhibit an enzyme that breaks down norepinephrine, a hormone involved in fat breakdown, increasing its levels and promoting fat metabolism.
It is important to understand that the scientific evidence supporting the efficacy and safety of many non-prescription and herbal weight loss options varies considerably. Unlike prescription medications, dietary supplements generally do not undergo pre-market review or approval by the U.S. Food and Drug Administration (FDA) for safety and effectiveness. Manufacturers are responsible for ensuring their products are safe and accurately labeled, but the FDA primarily takes action after a product is found to be unsafe or makes unsubstantiated claims. Therefore, consulting a healthcare professional before using any non-prescription or herbal weight loss product is recommended to discuss potential benefits, risks, and interactions with other medications.