Can diet pills really help you lose weight?

ByDonald L. Leech

Jun 14, 2022

Despite what you may have heard from the many TV and online advertisements you have seen, there is no scientific evidence that supplements can help you burn fat without watching your diet or exercising.

Generally, many products marketed as weight loss pills belong to the category of dietary supplements. Therefore, since they are not classified as drugs, they are not subject to FDA regulations, which means there is not enough credible research to determine if they work.

However, while there is no evidence that diet pills work, the answer differs depending on who you ask. Doctors, for example, rely on scientific evidence, research and clinical trials – the absence of which leads them to conclude that diet pills are a marketing gimmick.

On the other hand, ask any weight loss coach and there’s a chance they’ll agree that these pills work. However, a trainer will also tell you that they only work when combined with proper diet and exercise.

Nevertheless, although supplemental diet pills do not work from a medical standpoint, there are prescription drugs that have been scientifically proven to help you lose weight.

Can prescription diet pills help you lose weight?

Yes, prescription diet pills have been clinically proven to help people lose weight. However, the reason they are not as popular is that they are prescribed by doctors to patients who are at risk of serious health problems due to their weight.

As a result, most people who want to lose weight cannot get these slimming pills because their weight has no adverse health effects.

Who is a candidate for prescription diet pills?

Prescription weight loss pills are a great alternative for people who have tried dieting and exercising without the results they desire. However, even with those pillsit is essential that you continue to exercise and watch your diet for optimal results.

A doctor will prescribe you weight loss pills if:

  • You have a BMI (body mass index) greater than 30
  • You have a serious health problem related to obesity (high blood pressure, diabetes, etc.) and have a BMI of 27 or more

Your doctor will review your medical history before prescribing these medications and explain their benefits and side effects. However, keep in mind that these pills are not suitable for everyone – it is strongly recommended that you avoid them if you are:

  • Trying to get pregnant
  • Pregnant
  • Breastfeeding

How effective are prescription weight loss pills?

According Mayo Clinic, regular use of prescription diet pills for more than 12 weeks can burn between 3-7% of your total body weight per year. Add to that the weight you would lose with lifestyle changes, including dieting and exercise, and the pounds add up considerably by the end of the year.

Although it may seem like an insignificant number, losing more than 5% of your total weight per year can lower blood pressure and blood sugar and significantly reduce your risk of heart disease.

Do prescription diet pills have side effects?

Yes, like most medications, prescription diet pills have side effects, including:

  • Diarrhea
  • Nausea
  • Constipation

However, serious side effects are rare. But what you may need to keep in mind is that you could regain the weight you lost if you stop taking these drugs. Nevertheless, maintaining an active lifestyle and watching what you eat will help you stay fit and prevent excessive weight gain.

How long should I take prescription diet pills?

A typical dose lasts about 6 months, after which your doctor will assess progress to determine if the pills are helping. If you have lost a lot of weight during the six month period to lead a healthy life, you may no longer need to take them.

However, if the doctor determines that the medications have not had the desired effect, he is most likely to recommend that you continue taking the pills or prescribe another weight loss pill.

Which Prescription Weight Loss Pills Are FDA Approved?

Unlike supplements, prescription weight loss pills are categorized as drugs and are therefore subject to FDA regulations. For you, this means that these drugs have been tested and found to be safe for human consumption and effective in doing what they claim.

So, if you need to take medication for weight loss, go for prescription pills as they are the safest option. There are three main prescription weight loss pills approved by the FDA for long-term use, namely:

  • Orlistat sold as Xenical
  • Bupropion-naltrexone marketed as Contrave
  • Phentermine-topiramate sold as Qsymia

Typically, these medications decrease your appetite or increase feelings of fullness. While some do both, others like Orlistat work differently – it interferes with fat absorption.

Below is a brief overview of the three diet pills, what they are most common for, and their side effects.


This medication is most often used as a treatment for opioid and alcohol addiction. It is also an antidepressant and has been found to help smokers quit smoking. However, it has significant side effects, including:

  • High blood pressure
  • Nausea
  • Constipation
  • Headache
  • Suicidal risk


Although this drug is only available by prescription, it has a weaker variant called Alli which is available without a prescription. However, if you want faster results, stick to the prescription variant.

It is essential that you switch to a low fat diet when using Xenical for best results. Like most medications, it also has side effects such as loose stools and flatulence. At worst, the drug is thought to cause severe liver damage, although this is extremely rare.


Qsymia is a fusion of the anticonvulsant known as topiramate and the weight-loss drug phentermine. While it is one of most effective appetite suppressantit also has serious side effects, including nervousness, insomnia, high heart rate and high blood pressure, and an increased risk of birth defects.

Yet its biggest drawback is that it is most susceptible to abuse due to its addictive nature.

final verdict

Although prescription diet pills are effective, medication is not the safest option if you want to lose weight. The best you can do is change your lifestyle to a more active one that involves exercise and a regulated diet.