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Phentaslim Review - Does This Metabolism Booster Work?

By Summer Banks on Nov 15, 2016
Phentaslim Review

Looking at some diet products can be painful, especially if there’s no scientific backing for the formula. Let’s find out if Phentaslim is in this group. We did some intensive research and created one of our in-depth reviews, examining the side effects, ingredients, clinical studies and overall customer service. Also, we scoured hundreds of dieter experiences found online. At this point, we compressed all the data to give you the info you need.


What is Phentaslim?

To start, Phentaslim is a metabolism booster. The ingredients are guarana seed, [1] caffeine anhydrous, green tea extract, magnesium, zinc acetate, cayenne pepper, [2] panax ginseng root, L-tyrosine, L-theanine and L-carnitine. Supposedly it helps by boosts energy levels, decreases hunger and reduces excess body fat. This should be taken 20 minutes prior to breakfast, lunch and dinner along with a glass of water.

Phentaslim is made by Optimum Nutra Inc. and has been available since 2012. It can be purchased via the official website for $59.99. This supplement is backed by a 30-day satisfaction guarantee and there are some user testimonials posted on the website, but read on…

Fad Diet Ingredients – “No Proof?”

The first thing we felt needed attention with Phentaslim ingredients was the fact that some are nothing more than a fad. “This one relies on an unproven formula that contains cayenne pepper and panax ginseng root; [3] neither of which has been proven to assist with weight-loss or fat reduction,” said our Research Editor.

One customer stated, “Not effective at all. Been taking for six weeks now.”

“Another scam pill. Doesn’t work like it’s supposed to.”

Negative User Reviews of Phentaslim – “That’s Not Good”

It’s always a good idea to check out customer reviews posted online. We discovered that one person stated, “I started Phentaslim on 6th Dec. Not seen any weight-loss yet. But I feel more energy.[4] But since couple of days I am feeling dizziness and heavy head after consuming the medicine. The headache is quite a lot.”

Another said, “Serious jitters and nausea from this diet pill.”

After doing some extensive research, we came to the conclusion that if there is an individual aspect of a fat loss pill or diet system that is quite troublesome (too many negative reviews, fad ingredients, serious side effects) the true likelihood of lasting weight-loss results is minimal. This means if Phentaslim does result in a lot of discouraging claims, this could be a serious dilemma.

The Science – “Clinical Backing?”

Even though the official website states that Phentaslim uses ingredients that are supported by clinical research, we could not find the actual studies presented by the company. This is a shame, because there are a few bright lights in there. [5] Here at DietSpotlight, we need to see documentation of real science before we can get behind a weight-loss product.

The Bottom Line – Does Phentaslim Work?

Well now, has the time come to rush out for this one? While there is definitely a lot of hype surrounding Phentaslim capsules, we aren’t comfortable recommending this weight-loss formula. The reality is there are only two customer testimonials posted on the official website and it does use some fad diet ingredients. Not to mention, Phentaslim is associated with side effects.

If you want to see more fat loss results, we advise you to select a supplement that is supported by plenty of positive customer reviews, does not cost a fortune and does not rely on fad diet ingredients.

Among the best products we’ve seen in 2016 is one called Leptigen. This supplement contains four unique ingredients, which have been shown via clinical testing to help enhance fat loss and increase metabolism. Customer comments found on the internet show people are seeing amazing results.

We find it a show of confidence that the company behind Leptigen is offering a Special Trial Offer, which is a good sign.

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About the Author:

Summer Banks is an ISSA-Certified Fitness Nutrition Specialist and has reviewed over 2000 diet products. She has years of nursing training, experience as a manager responsible for 15 supplement brands, and completed coursework on Food and Nutrition from Stanford University. full bio.

How Does Phentaslim Compare?

Previous Phentaslim Review (Updated June 17, 2014):

Phentaslim - What You Should Know

Phentaslim is a fat burning, weight loss supplement that looks pretty fantastic at first glance. A complete list of ingredients, with amounts for each, contact phone number and clinical support for ingredients are all listed on the official website, but when we looked deeper into the company there are a few red flags customers need to know about.

List of Ingredients


  • Thiamin
  • Riboflavin
  • Vitamin B6
  • Vitamin B12
  • Zinc
  • Niacin
  • Guarana Seed
  • Caffeine Anhydrous
  • Green Tea Extract
  • Cayenne
  • Raspberry Ketones
  • L-Tyrosine
  • L-Carnitine
  • 5-HTP
  • Panax Ginseng Root

Product Features of Phentaslim

The first six ingredients in the formula are nothing more than everyday vitamins. Pull out that bottle of vitamins you take every morning and you’ll likely find every one of these ingredient in higher doses, most of the time. Taking more of these vitamins and minerals is not going to improve overall health or weight loss. B vitamins are often marketed to increase energy, but the short half-life and the body’s inability to store the vitamins means a barely noticeable bump in energy before the body pushes those B vitamins out during urination. Most of the time with supplements intended to lose weight, don't always work. One thermogenic that has other great ingredients like Phentalsim, is Hydroxycut, which can be taken once or twice daily for the best weight loss results.

Moving on to the active ingredients, we notice nothing spectacular. Guarana, green tea and caffeine are all proven to boost energy and metabolism. And if it's caffeine and energy you seek, you may want to take a close look at Cellucor Super HD, which carries various ingredients for energy, fat burn and appetite suppressants. What dieters are looking for is this huge bump in energy and mood so they feel like eating right and exercising. That is not exactly what Phentaslim will provide. We like the fact that Phentaslim adds only 100 mg of caffeine, but guarana and green tea are both sources of caffeine, so there is more than 100 mg per serving. We have no idea how much caffeine these ingredients add, but if both are standardized to just 50 mg of caffeine the dose jumps to 200 mg per serving. We found no appetite suppressant in Phentaslim, another huge problem. Caffeine increases metabolism and thus increases hunger.

A hidden problem with Phentaslim is revealed in the terms and conditions. If order Phentaslim and you just don’t like the product, you can return it for a refund, but you will pay $10 for the return, you will not receive a refund for and original or return shipping costs and the company retains your personal contact information to sell or share with other companies. If this seems to risky, perhaps an alternate choice for weight-loss is offered with Ideal Shape. They uphold to their money-back guarantee.

See Our Featured


  • All ingredients are listed online.
  • Not too much caffeine is included per dose.


  • There are multiple stimulants in the formula.
  • The company charges a return fee.
  • Your personal information will likely be shared with other companies.

Phentaslim - Conclusion

Most of the ingredients in Phentaslim are well-known, clinically tested and safe for use by healthy dieters, but the gauge of a good company is about more than just the ingredient list. Behind the scenes we find a company that sells or shares your personal information and charges you to return the product if it doesn’t work for you. You can find a more effective supplement from a trustworthy company.

Phentaslim Questions & Answers:

We boiled down hundreds of user comments about Phentaslim into this helpful FAQ.

What are the side effects of Phentaslim?

Phentaslim side effects may include jitters, nausea, dizziness, and headache.

What are the ingredients in Phentaslim?

Phentaslim ingredients are green tea [1], caffeine, l-theanine, l-carnitine, l-tyrosine, panax ginseng, guarana seed, magnesium, cayenne pepper, niacin, zinc, black pepper extract, vitamin B6, riboflavin, thiamin, and vitamin B12.

Does Phentaslim work?

The Phentaslim formula is not bad. It contains green tea and caffeine, two important ingredients. [2] However, you can find these in hundreds (if not thousands) of other products. Some parts of the supplement have no clinical support.

How much does Phentaslim cost?

Phentaslim costs $59.99 for 90 capsules.

How should I take Phentaslim?

You should take Phentaslim three times a day, once 20 minutes before breakfast and lunch and once in the late afternoon. It is not suggested to take Phentaslim after 5pm.

Can I take Phentaslim if I have a health condition?

You should ask your physician if you are under the age of 18, if you are taking prescription medications, have other underlying health problems, are pregnant, or nursing.

What do users like about Phentaslim?

Users liked that Phentaslim may curb appetite, increase energy levels, and there is a money-back guarantee.

What do users NOT like about Phentaslim?

Users don’t like how Phentaslim has multiple stimulants in the formula and how pricey it is.

How do I contact Phentaslim customer service?

You can contact Plentaslim customer service by emailing them at cs@phentaslim.com or by going to their contact page on the official website.

Is there an official website for Phentaslim?

Yes, there is an official website for Phentaslim.

Do you know how much of each ingredient is in the formula?

Yes, the amount of each ingredient used in Phentaslim are listed on the official website.

Does Phentaslim come with a guarantee?

Phentaslim has a 60-day money back guarantee.

You might ask yourself, is this product or that diet going to work for me? Truth is time will only tell as all individuals respond uniquely to weight loss results. Leptigen, is among one of the best products surfaced in 2016 to boost the metabolism and fat loss, noticing unbelievable weight loss transformations in consumers.

Phentaslim Side Effects:

Nowadays, weight-loss supplements are abundant. This doesn’t mean the natural solution is the one with zero negative effects. With each and every formula there’s a potential for an adverse reaction, while Phentaslim side effects are rare, it doesn’t necessarily mean they don’t happen for some users.


Nausea is the queasy, uncomfortable, sick feeling that typically precedes vomiting. Nausea creates an inclination to vomit as a warning system in your body. It may be trying to expel toxins or may indicate an inner ear or other disorder. It is most often associated with a viral infection or food intake.

What causes nausea?

The timing is everything. When appearing after a meal, it usually indicates an issue with digestion or the food you ate. If nausea occurs randomly, it could mean an inner ear imbalance or disturbance, inflammation of the stomach lining (gastritis), or ulcer.


Constipation is usually described as having one to three (in rare cases none) stools in a week. The body could experience hardened stool, straining or exertion while trying to make a bowel movement, and abdominal discomfort. [1]

What causes constipation?

Constipation is usually caused by the slow distention of food through any part of the intestine or colon. This can be caused by narcotic pain medications, anti depressants, or iron supplements.


Headaches are most commonly referred to as dull, sharp, or throbbing pain in the head and neck region of the body. The types of headaches are migraine, cluster headaches, and most the common, tension-type headaches which feel like extreme pressure in your skull.

What causes headaches?

Headaches are caused by overactive or problematic nociceptors that reside in nerves and muscles around the body. These nociceptors indicate pain and send the signal to the brain that something is wrong. Headaches could be caused by caffeine, stress, or overexertion of the body as well.


Dizziness is the feeling of faintness, or spinning. It’s an uncomfortable sensation that everything is whirling around you, even though you are stationary. It’s a feeling of being unsteady, weak, or having a false sense of motion. [2]

What causes dizziness?

Dizziness can have a wide array of causes including inner ear infections, motion sickness, or infection. Dizziness is most commonly caused by any disturbance in the eyes, sensory nerves, or inner ears. The fluid in the inner ear detects gravity and changes in motion. When the fluids are disturbed they create a false sense of spinning.

Phentaslim side effects are indeed rare, however some users have reported dizziness, headaches, and constipation, among others. In order to protect yourself from any potential negative effects, it’s always best to seek the advice of a doctor before taking any supplement, especially if you are pregnant or nursing, under the age of 18, taking prescription medications, or have any pre-existing medical condition.

To state the obvious, every individual person responds differently with weight loss products; all leading to different weight loss results, some successful, others not. One that has been scrutinized for its incredible results, Leptigen, has been clinically proven to accelerate weight loss, undue weight-loss plateaus and ignite the metabolism.

Phentaslim claims to be a "revolutionary diet pill" that's natural and allergen free. There are clinical studies offered on the official website and some do link some ingredients to weight-loss. There's no doubt the user could notice increased energy, but weight-loss claims are over the top and unattainable for the majority.

Phentaslim Ingredients and Supplement Facts

Serving Size: 1 Capsule
Serving Per Container: 90
Amount per Serving % DV
Green Tea 375mg *
Caffeine 270mg *
L-Theanine 225mg *
L-Carnitine 200mg *
L-Tyrosine 200mg *
Panax Ginseng 120mg *
Guarana Seed 100mg *
Magnesium 80mg *
Cayenne Pepper 50mg *
Niacin 20mg *
Zinc 15mg *
Black Pepper Extract 6mg *

Other Ingredients: Vitamin B6, riboflavin, thiamin, vitamin B12

Bottom line, weight loss can be a long and tricky process. Among the best weight loss formulas surfaced in 2016, Leptigen promotes healthy benefits including accelerated fat loss, increase in energy and diminish weight-loss plateaus. It’s a dietary supplement highly regarded for weight loss.

8 User Reviews About Phentaslim

Leave comments below (moderated by Leptigen)
  • 1
    No change

    Took 30 day supply didnt have more energy and didnt help with weight loss even though i cut my portion size down ate healthy and excersised 5 days a week! wouldnt waist money buying it!


  • 2

    Totally waisted my money. Very disappointed. Didn’t reduced my appetite, didn’t speed up my metabolism in fact increased my appetite and gave me constipation. I do not recommend this produc!!!


  • 3

    TI have been taking this for two weeks with no weight loss. I have only been taking one a day because I did not want to be kept awake at night.


    Your Name

    Totally waist of my money .


  • 4

    i really like it im so happy im losing weight finally happy happy


  • 5

    I have to say when I particular read these reviews I thought that it sounded great. I took this just over one week and have to say not a good experience, jitters, sick feeling. I really thought after all the reading that this would not give you these type of sensations. I had a horrible feeling of sickness and jitters throughout my body to the point my hands were shaking. Definitely didn’t reduce my appetite but I think that the sickness was suppose to maybe put you off food. I would not recommend this product at all in any positive way.


  • 6

    People do not book it. It is absolutely useless, then they. promise refund. But I paid about 38 pounds. Instead of 38 pounds they returned only 26 saying that they should keep 10 £ for handling? Also unlike other companies they do not provide a pre-paid envelope to send it back demanding the letter to be sent registered, so they are CROOKS! I lost 20 pounds instead of complete refund! Feel disgusted


  • 7

    How long before I would expect to see results?


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