How Much Weight Can You Lose on Phentermine?

January 9, 2024 |

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How much weight can you lose on phentermine in a week, 2 weeks, and even a month?

Well, there is no generalized answer to your question because everyone has their unique weight loss journey, and the weight they lose on phentermine depends on several different factors.

Since you have asked this question, so if I make a guess, your doctor might have just prescribed you phentermine to help lose that stubborn fat, and now, you are impatiently searching for an answer to how fast it can yield the desired results.

Although your weight loss progress greatly depends on how consistently you pursue the changes in your diet and physical activity. But this is not all, and your genetics, environmental factors, gender, etc., are also some of the many things that decide how many pounds you can shed with phentermine in a specified duration.

In this article, I will talk about how much weight you can lose on phentermine, how to use phentermine to achieve sustainable weight loss, and what an over-the-counter alternative to this prescription drug is.

So, keep reading, and let me fill you in on the details.

How much weight can you lose on phentermine and topiramate?

You can lose around 5% to 10% of your initial weight on phentermine and topiramate.

Phentermine and topiramate is a combination drug that secured FDA approval on the basis of five major clinical trials in July 2012.

This drug combination is scientifically acclaimed for inducing effective, robust, and sustainable weight loss in obese individuals. And is commonly sold under the trade name ‘Qsymia.’

This combination drug comprises the anti-epileptic extended-release topiramate and the anti-obesity phentermine that work synergistically to aid chronic weight management in obese individuals.

The highlight of Qsymia is that it works over a longer duration and has a better tolerability profile.

However, it is controlled under Schedule IV of the Controlled Substances Act because of phentermine.

Doctors prescribe Qsymia to individuals who either have a BMI of over 27 kg per m2 and are suffering from at least one weight-related co-morbidity or if they have a BMI above 30 kg per m2.

It is prescribed once daily, mostly in the morning, in adjunct to a calorie deficit diet plan and an exercise routine.

Four of the five major clinical approval trials, namely EQUIP, EQUATE, CONQUER, and SEQUEL, found that that this drug combination helped the majority of participants achieve at least 10% of weight loss from baseline and many others were successful in achieving at least a threshold weight loss of 5% from the baseline.

Moreover, more than 50% of the participants in the study sustained this weight loss for up to 2 years.

And if you are curious, the fifth trial, FORTRESS, was designed to assess the teratogenicity potential of this drug combination.

Here is a summary of the weight loss progress reported in the results of these clinical trials performed on Qsymia:

  • The EQUIP trial treated 1267 obese patients with Qsymia for over a year. And 67% percent of these patients achieved a threshold weight loss of 5%.

In contrast, 47% of them achieved at least 10% weight loss over the course of the study.

  • The EQUATE trial was designed to monitor weight loss progress in patients who were treated with Qsymia for a period of 28 weeks.

And according to the results, 40.8% of the patients achieved at least 10% weight loss from their initial weight upon treatment with the maximum dose of this combination drug.

  • In the CONQUER trial,2487 obese patients were recruited and treated in with this combination treatment for 56 weeks.

And as a result, 70% percent of the patients achieved a weight loss of 5% from the baseline, whereas 48 percent of the participants achieved a weight loss of 10%.

  • In the two-year SEQUEL clinical trial, 79.3% of the study participants achieved a weight loss of 5% percent.

In comparison, 53.9% of the participants achieved a weight loss of 10% from the baseline.

In addition to the weight loss benefit reported in these clinical trials, an improvement in the glycemic index, a decrease in reports of new-onset type 2 diabetes, a reduction in the waist circumference, and a diminution in visceral fat deposits were also observed in the participants of the study.

How to lose weight with phentermine and keep it off?

Phentermine is a stimulant drug that suppresses your appetite to help you consistently follow your calorie-restricted diet plan and provide you with an energy boost so that you can last during your daily exercise.

This implies that phentermine needs to be paired up with a specific diet and some physical exertion because the drug on its own might not be that fruitful in promoting weight loss in obese individuals.

Again, the fact that phentermine is not doing anything on its own and just helping your body adjust to the lifestyle changes you are going to introduce should be enough to motivate you to commit to healthy routines even after you discontinue the phentermine prescription.

So that you can prevent rebound weight gain and maintain the weight loss you achieved.

The National Weight Control Registry (NWCR) is an organization that is following more than 10,000 individuals who could lose weight and manage to keep it off for the longest time.

And considering the different reported patterns of weight maintainers, here are some things that you need to be attentive to in order to use phentermine correctly to effectively and sustainably lose weight.

Diet changes

Adjusting your diet with phentermine is the only way you can achieve sustainable weight loss because, in the end, you are what you eat.

And once you are off this appetite suppressant, your cravings and hunger pangs will return, and only a nutritionally complete diet will help you withstand the calorie restriction required for weight maintenance.

Experts have estimated that the weight maintainers whom NWCR tracks eat around 1800 maintenance calories per day (when exercising).

So, you need to make an unfailing shift to a healthy low-fat, and calorie-controlled diet, catch up with your fruits and veggies daily and avoid processed foods, sugars, and junk food with or without phentermine.

In addition to this, it is recommended that you drink 8 glasses of water daily with phentermine as it may prevent dry mouth, which is one of the most commonly reported side effects of phentermine.

And getting accustomed to watching your daily water intake may also help in weight maintenance because water helps to burn calories, removes waste, and is a natural appetite suppressant.

Physical activity

Exercising while on prescription helps to prevent the phentermine plateau and helps burn more calories not only on prescription but also off it.

Moreover, researchers found that high-intensity exercise in hot conditions curbs the appetite as it suppresses the appetite-stimulating hormone ghrelin.

NCRW found that effective weight maintainers spend 1 hour of the day doing moderate-intensity exercises like brisk walking, weightlifting, cycling, and aerobics.

You may devote some time of the day to jogging, running, doing the treadmill, or any other moderate to high-intensity physical activity.

Weight monitoring

When your bariatrician puts you on phentermine, they may ask you to check your weight regularly to assess your weight loss progress so that they can adjust your prescription accordingly.

And if you don’t break this habit, it may help you to maintain your weight as well.

Regularly measuring your weight even after you are put off the drug may help to motivate you to keep working for weight maintenance.

And it will also help you to notice any weight gain and adjust it timely rather than getting you in weight predicaments later on.

Moreover, frequent weight monitoring is another habit that was reported in the weight maintainers tracked by NWCR; 44% of the participants reported that they stood on the weight machine at least once a day, and 31% reported monitoring their weight at least once a week.

Can you lose weight on phentermine without exercise?

Yes, you can lose weight on phentermine without exercise. As there are reports of weight loss that occurred with phentermine without introducing any changes in diet or physical activity.

Although doctors do recommend incorporating diet changes and exercise to lose weight with phentermine, a Reddit user ‘Riverfaile’ wrote in this Reddit thread that she lost 30 pounds with only phentermine in 3 months, without making any adjustments to her diet or exercise.

Two users on this Reddit thread also mentioned that they lost weight on phentermine without working out, but both of them said that they gained it back in the next couple of years.

Nonetheless, the user experience may vary, and this effect cannot be generalized to everyone since it is not the standard way to use the drug.

Moreover, phentermine is not a weight loss magic pill, and it has no other effect that could speed up your weight loss, like increasing the metabolism or speeding up the fat-burning process instead of just suppressing your appetite.

Nonetheless, phentermine should not be used as a replacement for diet or exercise.

And since obesity makes it hard to restrict calories and work out safely, you may use this drug to support your lifestyle changes.

Moreover, losing weight on phentermine alone might not prove beneficial in weight maintenance after you discontinue the prescription.

What’s better than conventional phentermine pills?

So, if you don’t want to try your luck with controlled substances and stimulants like phentermine because of their side-effect profile, Fret not.

Because in this section, I have shared an all-natural over-the-counter weight loss pill that can help you achieve your fitness goals without worrying about those threats that phentermine poses.

Yes, we’re talking about PhenQ appetite suppressant.

PhenQ bottle tablet

 ‘PhenQ’ is a weight loss pill manufactured by ‘Wolfson Berg’ which has been around for over 15 years and is one of the most trusted, reputable, and leading names in the supplement industry.

The PhenQ pills are designed with a 5-in-1 formula that has an appetite suppressant effect on the consumer and is also an oral fat burner that promotes rapid weight loss. The formula also prevents fat accumulation in obese individuals. And provides an energy boost and works to enhance mood and cognition.

According to the company, it has helped more than 190,000 users to lose weight, and the website has published reviews and success stories of individuals from around the world, which proves that this drug might be as good as they claim.

PhenQ is made with 100% vegan and proven ingredients that are reported to be safe and effective. And since it does not contain phentermine, so you don’t require a doctor’s prescription to buy it.

You can go for a risk-free purchase of authentic pills that are made in FDA and GMP registered facilities directly from their official website page right here.

The weight loss potential of PhenQ is not only backed by research, but user reviews have also poured in trust for it.

Average users report a weight loss of between 10 to 15 pounds per month with it.

Moreover, the PhenQ consumer results and reviews were also published in the Daily Iowan Newspaper.

Different users reported that they lost 22 pounds within 90 days, 11 pounds within 30 days, 35 pounds within 120 days, and 33 pounds within 60 days.

In case you find the scientific evidence more reliable instead of user reviews, you may scroll down their official website and find a list of the sources that will take you to the research that supports the effective weight loss potential of the product’s different ingredients.

The key ingredient in PhenQ is their trademarked formula, the ‘a-LACYS RESET,’ and the clinical trial performed on it found that it improves recovery and energy, increases lean muscle mass, and reduces appetite.

Other ingredients in PhenQ include caffeine and capsimax powder which promotes thermogenesis.

The nopal cactus and a natural mineral chromium picolinate suppress appetite and help to reduce fat accumulation.

And the Alpha-Lipoic Acid promotes energy production from carbohydrates in the body.

In addition to all this, PhenQ is generally a user-friendly product.

It may cause self-limiting side effects like bloating, nausea, headache, upset stomach, or dizziness in rare cases only.

However, you need to avoid these pills if you are under 18 years of age, are pregnant or breastfeeding, or are suffering from some illness.

The rest of you need to give it a go at least once if nothing else is working for you.

PhenQ is affordable as well as one bottle of it contains 60 pills and can be bought for $70 only.

Moreover, it is delivered free of cost around the world. You can also purchase 2 bottles for $140 and get one free with them.

The best part is that you are assured a 60-day money-back guarantee with your every purchase.


How much weight can you lose on phentermine in one week?

You may lose around 1 to 2 pounds per week while on phentermine, but since it takes about four to five days to build in the system, you might not see an immediate effect.

How much weight can you lose on phentermine in 2 weeks?

You may lose around 4 to 6 pounds or even 10 pounds in two weeks on phentermine. But the weight loss progress varies for every person.

How much weight can I lose with phentermine in a month?

The average weight loss reported in different studies varies, but you may expect to lose 3 to 6 pounds in a month if you are a woman.

Whereas if you are a man, you might lose 5 to 8 pounds in the same duration.

How much weight can you lose on phentermine in 3 months?

You may lose about 3% of your initial body weight in 3 months.

How much weight can you lose on phentermine in 6 months?

You may lose between 5 to 7% of your body weight in 6 months.

How much weight can you lose on phentermine 15mg?

According to the user reports, one obese patient lost 33 pounds in about 2 and a half months, and another user lost 19 pounds in 23 days while on 15 mg phentermine.


Phentermine will only ‘support’ your weight loss and not primarily ‘cause’ it. And your weight loss progress is increasingly dependent on the lifestyle changes you are willing to make.

It does not matter if the weight loss supplements you introduce in your regimen are phentermine or PhenQ.

Either of them will only produce sustainable results if you pair them with some exercise and a nutritionist-recommended diet.

To sum it up, you need to keep acting like a successful weight loser to become a successful weight loss maintainer.

And instead of abandoning all the good habits, you learned while you were prescribed some weight loss drugs, try to carry them with you through the rest of your life so that you never have to take any pills any more.

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