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Phentaslim Review

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Phentaslim Review

This product promises a lot of bold things, but can it really deliver? With today’s modern supplements, users demand results results fast. In this Phentaslim review we’re doing a complete tell all on Phentaslim and the companies behind it.. Fasten your seat belts.

Let’s take a look at the top level pros and cons of this product:

Phentaslim Benefits:

  • Comes with a 60 day money-back guarantee
  • Will significantly boost energy levels due to the stimulant content
  • Some research to suggest that caffeine helps increase metabolic rates
  • Formula contains B-vitamins
Phentaslim Drawbacks:

  • Phentaslim will not single-handedly burn body fat as implied – you’ll need to monitor your calorie-intake to see results.
  • Evidence to suggest the formula may increase appetite, rather than suppress it.
  • The extremely high stimulant content has the potential to be dangerous for those with high blood pressure.
  • Users of Phentaslim who wish to remain within a safe daily caffeine intake amount will not be able to consume much caffeine elsewhere in their diet.
  • Potentially negative side effects will make it unsuitable for certain people.
  • Returned items are minus £10 handling fee, returner is responsible for all return costs.

Phentaslim Review Not Recommended

Some Quick Information On This Product

We’re willing to bet that if you’re considering purchasing this product it’s because you’ve seen a gleamingly positive Phentaslim review on the popular review website “”. That website, much like ourselves, is a team of reviewers who take an analytical approach to supplements and inform readers on what they can and cannot expect from said product in question. While they often do some good work, exposing scam products and highlighting potentially dangerous products, there is a few things you should be aware of.

We believe that Phentaslim is manufactured by the same folks who run Diet Pills Watchdog, therefore we advise all our readers to be aware of the bias that may be in place here; we have noticed that typically the website ‘watchdog rejects’ all products they come across, with the exception of products produced by Optimum Nutra inc.

Readers should also be advised that the website is certainly not an ‘official’ watchdog, so whatever you read on there should be taken with a pinch of salt.

Phentaslim itself is a 3-per-day fat burner that is heavily formulated with stimulants and B-vitamins. The product costs a pretty steep $52.99 and will last users approximately 30 days should they consume the directed amount per day.

Company Background Information – Who Owns DietPills Watch Dog / Optimum Nutra Inc?

Phentaslim is produced by a company named “Optimum Nutra Inc”. We believe this is the same company who owns and operates Watchdog Media Inc /, though for absolute clarity we do not have conclusive proof on that, just a hunch.

Optimum Nutra Inc seems to be located in Panama and process their payments in Cyprus Via Opti Nutra Processing Limited.

With a little help from the kind folks over at, our researchers found that Optimum Nutra Inc and Opti Nutra Processing Limited appear to be shell companies and that the majority of operations is based out of the United Kingdom.

While digging through the Panama company records we could not find any information on Optimum Nutra Inc – it’s almost as if the company didn’t exist. After almost giving up our search we hit a breakthrough while using the databases available via OCCRP (Organised Crime & Corruption Reporting Project).

We found that the company based in Cyprus, Opti Nutra Processing Limited, has two UK-based directors and one Cyprus-based company named “Dedalos Enterprises (Cyprus) Ltd” acting as secretary. It makes logical sense to assume that these are the people behind the company.

For full information on who is behind Optimum Nutra we encourage our readers to check out the full OCCRP report here.

Does Phentaslim Work?

Perhaps the most important question of all.. does it work? Anybody who is considering spending the $52.99 should rightly want to know the answer:

We believe that Phentaslim will not work in the exact way the manufacturers suggest, but it still may be a decent product to lose weight with if you’re willing to control your diet and put in some work at the gym.

Firstly, anybody who is under the assumption that Phentaslim is a miracle product is sadly mistaken; this product is not going to strip you of your body fat while you chill out the couch watching Rick & Morty reruns.

The evidence suggests that this product may be able to help boost your metabolism, boost your energy levels and help reduce your perceived rate of exertion (RPE), but that’s about it.

We don’t believe Phentaslim will help suppress your appetite as there is no evidence to suggest that, rather the product may increase your appetite (explained in the claims section).

What Are The Phentaslim Ingredients?

We have found the following Phentaslim nutritional information from a user-generated picture of the bottle (see below).

Total Caffeine Content: 310mg per serving.

Three Capsules Contains: Panax Ginseng (10:1) 1200mg, Guarana Seed (4:1) 400mg, Green Tea (4:1), Caffeine Anhydrous 270mg, L-theanine 225mg, Acetyl L-Carnitine 200mg,  L-Tyrosine 200mg, Ginkgo Biloba Leaf Powder 120mg, Magnesium 80mg, Cayenne Powder, Black Pepper Extract 24mg, Niacin 20mg, Zinc 15mg, Vitamin B6 1.8mg, Vitamin B2 1.3mg, Vitamin B1 1.3mg & Vitamin B12 10mcg.

Phentaslim Ingredient Amount Label

As far as we can tell, Phentaslim is not suitable for vegetarians due to the capsules being Gelatin.

What Are The Phentaslim Side Effects & Safety Information?

We have compiled the following list of potential side effects Phentaslim may produced, based on the ingredients and amounts inside the formula:

Insomnia, nervousness and restlessness, stomach irritation, nausea and vomiting, increased heart rate and respiration. [1]

Can cause a short, but dramatic increase in your blood pressure, even if you don’t have high blood pressure. [2]

Can cause the urine, breath, and sweat to have a “fishy” odor. [3]

Noteworthy information: As Phentaslim contains a rather large 310mg per 3 capsule serving, we advise that users of this product highly limit the amount of caffeine they consume elsewhere in their diet. A study by EFSA stated that the safe cut off limit for healthy adults is 400mg of caffeine per day – exceeding this amount could have negative implications.

For reader reference:

Cup of filter coffee – 90mg
Standard energy drink – 80mg
Espresso – 80mg
Cup of tea – 50mg
Can of cola – 40mg
Bar of dark chocolate – 25mg
Bar of milk chocolate – 10mg


DietProbe Warning: Users of this product should be aware it is not suitable for people who are pregnant or breastfeeding due to the caffeine content. This product has the potential to aggravate anxiety and bipolar disorders. If you suffer from bleeding disorders, diabetes, high blood pressure, heart problems or IBS you should consider avoiding usage of Phentaslim (source). This product is not suitable for children.

What Are The Claims On Phentaslim?

We have found the manufacturers making the following claims about Phentaslim:

  1. Destroy Your Hunger Pangs – Misleading / Potentially False
  2. Annihilate Your Body Fat – Misleading
  3. Clinically proven weight loss ingredients – False

In regards to claim 1, we found a scientific study conducted by Sweeney P et al. that suggested that, rather than suppress appetite, caffeine may actually increase appetite. While some people claim caffeine suppresses the appetite, there is no actual conclusive scientific evidence to support this therefore we believe it to be a misleading statement.

When looking at claim 2, we feel that Phentaslim are being somewhat misleading again; yes there have been studies to suggest caffeine can boost metabolic rates for up to 3 hours when users consumed 3mg/KG of body weight, but a simple boost in metabolic rates will not “annihilate your body fat” as implied. The boost in metabolism will simply allow your body to burn more calories, however if you’re not actively monitoring how many calories you’re consuming, the impact of such metabolic boost can be minimal.

Claim 3 is just outright false; there are no clinically proven weight loss ingredients inside this product.

Are There Any Reviews From Customers?

We have found the following Phentaslim review testimonials from customers online:

Waste of money
By Beverley Hartles, Ewshot, Surrey, England, Jul 13, 2017 Verified Reviewer
Phentaslim is a total waste of money. I have not lost an ounce and am very active and have been on a calorie controlled diet while taking them exactly as requested.

I believe they are falsely advertising a product that does not work.

Bottom Line: No, I would not recommend this to a friend


Product DOES NOT work!
By Marc, Monroe, LA, Apr 3, 2017 Verified Reviewer
Their website states they have a 100% money back guarantee, but beware! These diet pills DO NOT work. Once you buy them, you own them because they will not refund your money as they advertise. Don’t waste your money.

Bottom Line: No, I would not recommend this to a friend


On the flipside, the product is described as a top rated product according to Watchdog Media Inc:

Phentaslim Pros
Over 100,000 customers
Clinically proven weight loss quantities
Made in a “GMP” certified facility with solid ingredient profile
60 day money-back guarantee


Where Can I Buy This Product?

This product is only available from the official Phentaslim website. It is not available in stores or on amazon, however we managed locate a few business sellers who carry the product on eBay.

Our Conclusion.

To conclude our Phentaslim review, we do not recommend this product. While it’s certainly not a terrible fat burner, it’s not the best we’ve ever seen. We don’t fully approve of the ultra-high price point of the product, nor do we like the misleading claims that we see on the manufacturer website.

If you’re looking for a great fat burner pill, we recommend you check out our top rated product Thermaxin.

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Lucy Blevins, PhD on FacebookLucy Blevins, PhD on Twitter
Lucy Blevins, PhD
Lucy Blevins, PhD
Health Editor at DietProbe
Lucy holds a PhD in Nutritional Sciences and is the editor-in-chief here at She has analysed and reviewed thousands of different products in the supplement industry and loves helping our readers find the perfect supplement!