From the Guidelines
Phentermine is the most commonly prescribed appetite suppressant for weight loss, with a typical dose of 15-37.5mg daily, as it has been shown to be effective in reducing hunger and increasing resting energy expenditure 1. Several other effective appetite suppressants are available for weight loss, including prescription medications and over-the-counter options.
- Prescription medications include:
- Phentermine-topiramate (Qsymia, 3.75-23mg/46-92mg daily) which targets different sites simultaneously to have an additive effect on weight loss 1
- Lorcaserin (Belviq), a serotonin receptor agonist that reduces food intake and increases satiety 1
- Bupropion/naltrexone sustained release (Contrave), which activates POMC neurons in the arcuate nucleus to release alpha-melanocyte–stimulating hormone, a potent anorectic neuropeptide 1
- Liraglutide (Saxenda), a GLP-1 analogue that reduces energy intake by reducing appetite, increasing satiety, and delaying gastric emptying 1
- FDA-approved over-the-counter options include fiber supplements like glucomannan (3-4g daily before meals) and green tea extract (containing EGCG, typically 250-500mg daily) These suppressants work by either affecting brain chemistry to reduce hunger signals, slowing stomach emptying to prolong fullness, or creating physical fullness in the stomach. For best results, appetite suppressants should be used alongside calorie reduction and increased physical activity, with regular medical supervision to monitor side effects. Most prescription options are intended for short-term use (3-6 months) except for semaglutide which can be used long-term under medical supervision. It is essential to note that the choice of appetite suppressant should be individualized, taking into account the patient's medical history, current health status, and potential side effects 1.
From the FDA Drug Label
CLINICAL PHARMACOLOGY Phentermine hydrochloride is a sympathomimetic amine with pharmacologic activity similar to the prototype drugs of this class used in obesity, the amphetamines. Actions include central nervous system stimulation and elevation of blood pressure. Tachyphylaxis and tolerance have been demonstrated with all drugs of this class in which these phenomena have been looked for Drugs of this class used in obesity are commonly known as "anorectics" or "anorexigenics". WARNINGS Phentermine hydrochloride tablets are indicated only as short-term monotherapy for the management of exogenous obesity.
The available appetite suppressors for weight loss include:
- Phentermine (2), which is commonly known as an "anorectic" or "anorexigenic" drug. Note that orlistat (3) is a weight loss aid, but it is not explicitly described as an appetite suppressor in the provided drug label. It has not been established that the action of such drugs in treating obesity is primarily one of appetite suppression. Other central nervous system actions, or metabolic effects, may be involved.
From the Research
Available Appetite Suppressors
The following are some of the available appetite suppressors for weight loss:
- Phentermine, diethylpropion, benzphetamine, and phendimetrazine, which are sympathomimetic drugs that mimic the effects of norepinephrine 4
- Sibutramine, a norepinephrine-5-hydroxytryptamine reuptake inhibitor, which is approved for long-term use 4, 5, 6
- Fenfluramine, which promotes serotonin neurotransmission and has been shown to reduce appetite and food intake 5, 7
- Dexfenfluramine, a dextrorotatory stereoisomer of fenfluramine, which has a suitable pharmacological profile for use in obesity treatment 7
- Plant extracts such as Caralluma fimbriata extract and a combination supplement containing Garcinia cambogia plus Gymnema sylvestre, which have been shown to be effective in reducing body weight through appetite suppression 8
- Orlistat, a lipase inhibitor, which reduces fat absorption and has been shown to reduce and maintain weight for up to 4 years 6
Mechanisms of Action
These appetite suppressors work through various mechanisms, including:
- Releasing or mimicking the effect of norepinephrine (noradrenaline) 4
- Inhibiting reuptake of norepinephrine or 5-hydroxytryptamine (serotonin) 4
- Binding to gamma-aminobutyric acid receptors or cannabinoid receptors 4
- Promoting serotonin neurotransmission 7
- Reducing fat absorption 6
Safety and Efficacy
The safety and efficacy of these appetite suppressors vary, and they should be used under the guidance of a healthcare professional. Some of these medications have been shown to be effective in reducing body weight, but the effect is often modest and should be combined with lifestyle modification 6. Additionally, some of these medications have been associated with side effects, and their use should be carefully monitored 5, 7.