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Best Weight Loss Pills: Prescriptions vs Natural Supplements

Best Weight Loss Pills: Prescriptions vs Natural Supplements

By Kire Stojkovski M.D
Editor Jonathan Hoarau Published 17 May 2023
Time to read 7 min
Exercise and a balanced low calorie diet are necessary for a healthy weight loss program. Adding weight loss pills to your program may be the most effective way to lose weight and fat if you’re struggling with obesity.
Get the lowdown on the top picks for weight loss pills with this review, where we see what science has to say about reaching a healthy weight.

Weight Loss Supplements and Pills

You have many fat burning supplements to choose from if you want to lose weight while you exercise, from prescription pills to over-the-counter natural options.
One of the main advantages of a nutrient-rich, over-the-counter supplement is that you’ll run into less additives, allergens and possibility of adverse side effects.
On another hand, not every supplement works for everybody. That’s why we reviewed the top substances found in these options to see what these pills have to offer and how each works.

Over the Counter Natural Pills That May Actually Work

Six of the best over-the-counter natural appetite suppressants and and supplements are as follows:

1. PhenQ - Best Weight Loss Supplement Overall

PhenQ includes:

  • Calcium carbonate
  • Chromium picolinate
  • Piperine extract
  • Niacin powder
  • Capiscum extract
  • Caffeine anhydrous
  • Nopal
  • L-Carnitine tartrate

a-LACYS RESET is a proprietary substance made by the PhenQ manufacturers and the main component of PhenQ. It contains common diet ingredients, such as alpha-lipoic acid, an antioxidant and anti-inflammatory, which helps the body convert carbohydrates into fuel [1].
This blend also contains cysteine, an amino acid and protein building block. You’ll find this ingredient in eggs, turkey, yogurt and other protein sources. Not only does it help you use energy efficiently, but it also aids in other metabolic processes and can improve immunity.
Piperine extract is the alkaloid found in black pepper that lends the spice its bold aroma and flavor. The bioavailability of this ingredient includes an anti-inflammatory quality and support of the digestive processes, an important component of weight loss [2].
Piperine also has a “heat-inducing” effect on the body, through the process of thermogenesis. This helps boost metabolism and one’s ability to burn fat in the body.
Niacin powder comes from the vitamin, B3. It may be useful for regulating cholesterol levels, preventing heart disease and treating type 1 diabetes.
Niacin is yet another ingredient in this supplement that plays a role to boost metabolism.
Nopal comes from a cactus plant that’s native to regions in Mexico. It’s a known antioxidant and may also be used to fight inflammation, fatigue, liver conditions, pain, wounds and ulcers.
Where weight loss is concerned, the high fiber content in this plant could support robust digestion [3]. It may also be useful for lowering blood sugar levels and insulin, as well, for those with diabetes.
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2. Trimtone — Best Weight Loss Pills for the Busy Woman

Trimtone has:

  • Green tea
  • Green coffee
  • Caffeine
  • Glucomannan
  • Grains of paradise

Green tea and green tea extract is a common ingredient found in weight loss pills. This is because it may help reduce appetite, improve energy levels, and it contains caffeine and catechins.
Catechins are enzymes that act as antioxidants, benefiting people in different ways [4]. One, in particular, called “EGCG” may play an important role in the breakdown of fats, speeding up the metabolism in one’s body.
Grains of paradise comes in as a more unique ingredient here. Also known as “alligator pepper”, these seeds are used as a spice and may offer other digestive benefits including the alleviation of diarrhea.
This grain may also help in offsetting the side effects of heart disease, while others have used it to help burn fat, though studies are inconclusive at this time.
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3. Zotrim — Best Appetite Suppressor for Weight Loss

Diet substances in Zotrim include:

  • Vitamin B3 and B6
  • Yerba Mate leaf extract
  • Guarana seed extract
  • Damiana leaf extract
  • Caffeine

Both vitamins B3 and B6 boost metabolism and heart health[5]. B6, in particular, may also help reduce water retention and inflammation, further boosting the weight loss process.
Damiana leaf extract comes from the Damiana plant and has long been considered as an aphrodisiac. It’s grown easily in tropical climates and may also play a role in treating symptoms of anxiety and diabetes.
It may also help speed up digestion, and cause “loose stools”, which could help in the excretion of fat deposits.
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4. Instant Knockout — Best Weight Loss Supplement for Training

Instant Knockout contains:

  • Green tea extract
  • Vitamin B6
  • Cayenne pepper seeds
  • Vitamin B12
  • Glucomannan
  • GTF chromium
  • Caffeine anhydrous

Vitamin B12, similar to other B vitamins, supports DNA synthesis and the metabolic processes. It provides energy, as well, which is useful when undergoing a strict caloric guideline.
Foods that are high in B12 include meat, fish, eggs, poultry, fortified breakfast cereals and milk products. For vegetarians, you can find vitamin B12 in Shitake mushrooms and nutritional yeast, to name a few sources.
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5. Leanbean — Best Weight Loss Supplement for Women

Items in Leanbean are:

  • Glucomannan
  • Choline
  • Chromium picolinate
  • Vitamin B6 and B12
  • Chloride
  • Piperine
  • Green coffee
  • Turmeric
  • Garcinia cambogia
  • Acai berry
  • Zinc

Choline is yet another ingredient here that supports metabolism. It’s found in eggs, beef liver, broccoli, nuts and cauliflower.
Garcinia cambogia comes from the Sap tree and aids in digestion, though it’s perceived effect on fat loss directly isn’t conclusive.
Zinc comes with various benefits, backed by science. It’s proven to lower inflammation and may cause a reduction in appetite, which aids in portion control while dieting and may lead to greater weight loss [6].

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6. Garcinia Extra — Best Weight Loss Pills When Dieting

Garcinia Extra ingredients include:

  • Garcinia cambogia
  • Raspberry ketones

Raspberry ketones are often touted in the weight loss world as beneficial for weight loss and burning fat away. This is due to its influence on the hormone, adiponectin, which regulates metabolism and one’s body composition.
This ingredient is also an antioxidant, supporting the immune system and helping fight off aging effects on the body.
Garcinia has minimal side effects, if any. Being an all-natural plant-derived product, it is suitable for vegetarians and vegans. However, if you are under 18 years of age, pregnant, or nursing, you should not use it.

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The Science Behind Popular Weight Loss Pill Ingredients

You’ll find some of these popular weight loss pill ingredients in these weight loss pills above. But what does science have to say?

  • Guarana
  • Caffeine
  • Yerba mate
  • Capsimax powder
  • Chromium picolinate
  • L-carnitine fumarate
  • Green coffee bean
  • Glucomannan
  • Cayenne pepper seeds

Guarana is a flowering plant, native to the Amazon region. It contains caffeine and is used to treat hypertension. Guarana may also have a positive effect on energy expenditure and metabolism, further benefitting obese individuals [7].
Caffeine functions as a stimulant and appetite suppressant, which is why you’ll often find this ingredient in weight loss pills and diet capsules. While studies don’t fully back the hypothesis, caffeine is shown to cause a minor impact over short spurts during the day [8].
Yerba mate is another plant here that’s native to South America. Many people have used it for medicinal purposes where it can supposedly increase focus, physical performance and energy levels. Yerba mate may also support the metabolism process.
Capsimax powder comes from capiscum, or the red pepper plant. This vegetable works to promote heat, aiding in the digestion and metabolic processes. Unfortunately, studies are not conclusive at this time.
Chromium picolinate may help in building muscle mass, as it’s essential for protein synthesis. Chromium may also play a positive role in digestion. It might also improve body composition and help with fat loss [9].
L-carnitine fumarate is an amino acid which helps the body utilize fat effectively. This indicates that it also supports metabolic processes, supporting weight loss as it helps convert fat into energy. L-carnitine fumarate also aids in brain function and muscle movement.
Green coffee bean comes in as another form of caffeine used in weight loss pills. It comes from raw coffee beans, before they’re roasted.
The reason for its popularity boils down to the chlorogenic acids inside the beans. These acids are antioxidants that also have an anti-inflammatory effect on the body. Several studies note the potential for green coffee beans to enhance weight loss efforts, though evidence isn’t definitive at this time.
Glucomannan comes from the Konjac plant, specifically the plant’s fiber-filled root system. It works to promote heart health and a robust digestive system [10].
Cayenne pepper seeds are a type of chili pepper that warms the body through thermogenesis and aids in digestion. Cayenne pepper may also speed up metabolism and curb your appetite, a necessary component to weight loss.

Prescription Weight Loss Drugs

Many people prefer a prescription weight loss drug to lose pesky pounds and cut calories. This is especially the case if any of the natural substances above are not suitable for an individual, possibly due to a preexisting condition.
Some of the top prescription weight loss drugs available include Orlistat and others:

1. Phentermine

Phentermine is primarily used as an FDA-approved appetite suppressant. Appetite control is an important aspect of weight loss, and this drug may be necessary for some people who find portion correction or containing cravings too challenging.
It is shown to be successful for weight loss and fat reduction [11]. Phentermine also works as a stimulant, so side effects may include an increase in your blood pressure and heart rate.

2. Topiramate

This drug was originally designed to help control seizures. However, some people have used it in combination with Phentermine above, for weight loss.
It’s also been used alone in treating weight loss of type 2 diabetes patients [12].
While Topiramate is FDA-approved for use in patients with seizures, it’s not approved as a weight loss remedy.

3. Liraglutide (Saxenda)

Liraglutide is one of the drugs for the treatment of type 2 diabetes. It increases insulin release and may improve blood sugar levels in obese individuals.
People take Liraglutide in injection form, which may be a deterrent for some individuals.

4. Naltrexone HCI and Bupropion (Contrave)

Contrave is a pill that contains both Naltrexone HCI and Bupropion. The former drug is for opioid and alcohol dependence, while the latter is prescribed for smoking cessation and depression.
For weight loss, if you take this prescription drug, it may help control appetite and remove additional calories from your diet.

Prescription vs Natural Weight Loss Pills

Taking prescription vs natural pills for a diet alongside an exercise routine is up to the individual, though both work.
Based on our list above, the only drugs that are made specifically for weight loss and are FDA approved are Orlistat and Phentermine. Even though they’re technically safe for use, it’s important to understand their side effects and speak with a doctor upon prescription request.
Common side effects of taking prescription weight loss pills like Orlistat are:

  • Diarrhea
  • Flatulence
  • Increase heart rate
  • High blood pressure
  • Insomnia
  • Nervousness

Certain people who are struggling with obesity may respond well to taking a prescription pill. This is especially if you find that one or more of the substances found in natural weight loss pills aren’t safe for you personally.
Again, this should be discussed with a trusted physician, but chromium is an example, as it’s not suited for individuals with liver disease.

Going Natural

Overall, most individuals could benefit from a natural option. While there are exceptions, given that most of the ingredients do come from natural sources, you know that they’re healthy and safe to use with few side effects.
If you’re looking to use a weight loss pill long term for obesity, a natural substance could be suitable. Many prescription choices are only suitable for short-term use, whereas the latter are often safe for use over long term periods.
Possible side effects are minimal for the majority of people. If you take these pills, they may cause:

  • Jitteriness (depending on caffeine dosage in pill)
  • Upset stomach
  • Bloatation

Most of the side effects listed above happen when used incorrectly. Do remember that even though these pills are natural, you shouldn’t overuse them or lose track of your schedule on a given day.
Make sure to follow the manufacturer’s instructions thoroughly and speak with a doctor or medical professional should any issue arise.

A Weight Loss Pill for Belly Fat

Phentermine is a popular drug option to take for stubborn belly fat. This is mainly the case because of how it works to limit appetite, which helps you lose pounds by cutting back on calories in general.
It’s not for obesity long term, though and it’s essential that you take other healthy measures, like exercise, to ensure permanent loss of belly fat.
Many, if not all of the manufacturers of the pills reviewed, prescription and natural, do state that these diet pills are not a magical cure-all to lose weight. Phentermine and other products like Orlistat need be supplemented by the following to ensure fat burning success:

  • Regular exercise routine
  • Low stress levels
  • Consistent sleep cycle (minimum 7 hours per night)
  • Low calorie, low fat diet full of fruits and vegetables


Taking fat burning diet pills to lose weight each day is an available method to make it happen as you cut the calories. You won’t lose pounds by simply popping one, though. Unfortunately, it doesn’t work that way.
Instead, you now know that you need to pair one of these pills with regular exercise, a limited calorie intake, low fat diet and a healthy sleep cycle for success.
Out of the pills we reviewed here, Orlistat is one option, though it may cause adverse side effects long term. Natural pills contain substances like green tea extract for a safer option to work over time.
If you’re struggling with obesity, you need to speak with a medical professional before you take any of the weight loss supplements for weight management above. This will help you avoid any poor consequences a pill may cause.

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1. Examine.com. “Alpha-Lipoic Acid Supplement – Health Benefits, Dosage, Side Effects.” Examine.com, 16 Aug. 2020, examine.com/supplements/alpha-lipoic-acid/.

2. “Piperine.” Piperine – an Overview | ScienceDirect Topics, www.sciencedirect.com/topics/agricultural-and-biological-sciences/piperine.

3. Uebelhack, Ralf, et al. “Effects of Cactus Fiber on the Excretion of Dietary Fat in Healthy Subjects: a Double Blind, Randomized, Placebo-Controlled, Crossover Clinical Investigation.” Current Therapeutic Research, Clinical and Experimental, Elsevier, 21 June 2014, www.ncbi.nlm.nih.gov/pmc/articles/PMC4109417/.

4. CS;, Lu H;Meng X;Yang. “Enzymology of Methylation of Tea Catechins and Inhibition of Catechol-O-Methyltransferase by (-)-Epigallocatechin Gallate.” Drug Metabolism and Disposition: the Biological Fate of Chemicals, U.S. National Library of Medicine, pubmed.ncbi.nlm.nih.gov/12695345/.

5. ML;, Kamanna VS;Kashyap. “Mechanism of Action of Niacin.” The American Journal of Cardiology, U.S. National Library of Medicine, pubmed.ncbi.nlm.nih.gov/18375237/.

6. CI. Gamboa-Gomez, NE. Rocha-Guzman, et al. “Zinc Supplementation Improves Body Weight Management, Inflammatory Biomarkers and Insulin Resistance in Individuals with Obesity: a Randomized, Placebo-Controlled, Double-Blind Trial.” Diabetology & Metabolic Syndrome, BioMed Central, 1 Jan. 1970, dmsjournal.biomedcentral.com/articles/10.1186/s13098-019-0497-8.

7. Lima, Natália da Silva, et al. “Guarana (Paullinia Cupana) Stimulates Mitochondrial Biogenesis in Mice Fed High-Fat Diet.” Nutrients, MDPI, 31 Jan. 2018, www.ncbi.nlm.nih.gov/pmc/articles/PMC5852741/.

8. Elsevier. Caffeine Affects Food Intake at Breakfast, but Its Effect Is Limited and Transient, www.elsevier.com/about/press-releases/research-and-journals/caffeine-affects-food-intake-at-breakfast-but-its-effect-is-limited-and-transient.

9. “Office of Dietary Supplements – Chromium.” NIH Office of Dietary Supplements, U.S. Department of Health and Human Services, ods.od.nih.gov/factsheets/Chromium-HealthProfessional/.

10. Keithley, Joyce K, et al. “Safety and Efficacy of Glucomannan for Weight Loss in Overweight and Moderately Obese Adults.” Journal of Obesity, Hindawi Publishing Corporation, 2013, www.ncbi.nlm.nih.gov/pmc/articles/PMC3892933/.

11. Kim, Kyoung Kon, et al. “Effects on Weight Reduction and Safety of Short-Term Phentermine Administration in Korean Obese People.” Yonsei Medical Journal, Yonsei University College of Medicine, 31 Oct. 2006, www.ncbi.nlm.nih.gov/pmc/articles/PMC2687747/.

12. Moradi, Sedighe, et al. “The Effect of Topiramate on Weight Loss in Patients with Type 2 Diabetes.” Journal of Research in Medical Sciences : the Official Journal of Isfahan University of Medical Sciences, Medknow Publications & Media Pvt Ltd, Apr. 2013, www.ncbi.nlm.nih.gov/pmc/articles/PMC3793374/.

13. Drew, Belinda S, et al. “Obesity Management: Update on Orlistat.” Vascular Health and Risk Management, Dove Medical Press, 2007, www.ncbi.nlm.nih.gov/pmc/articles/PMC2350121/.