While eating a well-balanced, reduced-calorie diet and exercising regularly are the cornerstones of weight loss, certain drugs can serve as powerful adjuncts.
One such drug is phentermine — one of the most popular weight loss drugs in the world. It has been proven effective for short-term weight loss when used alongside a reduced-calorie diet and exercise.
What Is Phentermine?
Phentermine is a prescription weight loss medication. It was approved by the FDA in 1959 for short-term use of up to 12 weeks for people older than 16.
In the 1990s, phentermine was combined with other weight loss drugs. This drug combination was commonly called fen-phen. After reports of significant heart problems in users, the FDA pulled the other two drugs used in the treatment — fenfluramine and dexfenfluramine — from the market.
Phentermine goes by the brand names Adipex-P, Lomaira, and Suprenza, or you can find it in combination medications for weight loss, such as Qsymia. It’s a controlled substance due to its chemical similarities to the stimulant amphetamine — making it available only with a prescription.
How Does It Work?
Phentermine belongs to a class of drugs called “anorectics,” also known as appetite suppressants. Taking phentermine helps suppress your appetite, thereby limiting how many calories you eat. Over time, this can lead to weight loss.
While the exact mechanisms behind the appetite-reducing effects of phentermine remain unclear, the drug is thought to act by increasing neurotransmitter levels in your brain. Neurotransmitters are your body’s chemical messengers and include norepinephrine, serotonin, and dopamine. When your levels of these three chemicals increase, your feeling of hunger decreases.
However, you may build a tolerance to the appetite-suppressing effects of phentermine within a few weeks. In that case, you should not increase your dose of the drug but stop using it altogether.
Effective for Weight Loss
Several clinical studies have proven that phentermine can boost fat loss. The expected average weight loss with phentermine use is 5% of your initial body weight. Yet, over 12 weeks, it can be as high as 10%. This equates to a weight loss of 10–20 pounds (4.5–9 kg) for a 200 pound (90.7 kg) person.
In a meta-analysis of six studies, people who took the average dose of 27.5 mg of phentermine for 13 weeks lost an average of 13.9 pounds (6.3 kg) compared to 6.2 pounds (2.8 kg) in placebo groups.
While phentermine has been shown to be effective for weight loss. it may work better when combined with topiramate. Topiramate is a drug that has been used on its own to treat seizures but — like phentermine — also has appetite-reducing properties. Topiramate and phentermine is a combination medication sold under the brand name Qsymia.
Compared to three other commonly prescribed drugs for weight loss, the combination of phentermine and topiramate was associated with the highest odds of losing at least 5% of the initial body weight. What’s more, research suggests that the phentermine and topiramate combination is the most effective weight loss medication to date — with people achieving an average weight loss of 21.6 pounds (9.8 kg) after taking the maximum dose for one year.
In users, this weight loss has translated to a significant decrease in waist circumference, improved insulin sensitivity, and blood sugar control, as well as favorable effects on triglyceride and cholesterol levels
Side Effects and Precautions
Phentermine alone is designed for short-term use only, as there are no long-term studies on its safety. However, the FDA has approved phentermine in combination with topiramate for long-term use, since the dosage of the two ingredients is lower than the maximum doses of the individual drugs.
You shouldn’t take phentermine if you have heart disease, hyperthyroidism, glaucoma, or if you’re pregnant or nursing. Phentermine should also not be prescribed in combination with monoamine oxidase inhibitors (MAOIs), a class of medications used to treat depression.
Healthy Ways to Promote and Maintain Weight Loss
While phentermine can be a powerful weight loss aid, the only proven way to shed weight — and to keep it off in the long term — is cultivating healthy lifestyle behaviors. Without making the proper changes, it is likely that you’ll gain back the weight you lost — and possibly more — once you stop taking phentermine.
A comprehensive lifestyle change includes:
- A reduced-calorie diet: If you have excess weight to lose, eat 300–500 fewer calories per day. A registered dietitian can help you tailor this range based on your preferences and goals.
- Prioritize nutrient-dense foods: Nutrient-dense foods— such as fruits and vegetables — are relatively low in calories and high in nutrients, such as fiber, vitamins, and minerals.
- Increase physical activity: Guidelines recommend a minimum of 150 minutes per week of moderate aerobic exercise, such as brisk walking or running.
- Behavioral strategies: Behavior changes includes regular self-monitoring of food intake, physical activity, and your weight, plus making adjustments as needed.
Making these lifestyle changes can be difficult and shouldn’t happen all at once. It will take an investment of your time and energy — but the outcome will be long-term weight loss and overall better health.
The Bottom Line
Phentermine is a prescription-only appetite suppressant and weight loss pill, approved for short-term use.
The combination of phentermine and topiramate appears to be even more effective and tolerable than phentermine alone.
Potential side effects include dry mouth, dizziness, fatigue, irritability, constipation and heart palpitations.
While phentermine can be a useful short-term weight loss tool, you must make healthy lifestyle changes for long-term success.
Glendale Whole Health promotes natural and holistic ways of improving health. There are natural alternatives to help suppress appetite. However, phentermine is a good way to start your weight loss journey and can be used on a short-term basis.
Call or write today for an appointment! (818) 551-0464 or email firstname.lastname@example.org.