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Sheena Jones
By Sheena Jones
January 21, 2013

According to, Phentaslim is “a helping hand to quickly burn your stubborn, unwanted fat.”

Phentaslim also claims to provide “supercharged metabolism, thermogenic fat burning, extreme energy, and mood support.”

Can Phentaslim really help you “get slim, ripped, and sexy…fast”? Let’s dig deeper and find out how effective it really is.

About the Manufacturer

Phentaslim is made by Optimum Nutra Inc., a supplement manufacturer established in 2011. Optimum Nutra’s mission is “to bring you the most pure and potent natural ingredients available and to provide effective supplements to maintain your health and wellbeing.”

The company also says, “Our primary commitments are quality, safety, and efficacy, and we guarantee every step in the manufacture of our products is in accordance with the strictest Pharmaceutical Good Manufacturing Practices.”

This sounds great, but it was difficult to find Optimum Nutra’s website. In fact, the website URL is “,” which was only discovered after a thorough search. It’s strange that Optimum Nutra’s information is so difficult to find. Supplement companies typically want websites to be easily accessed to better advertise their products and take in more business.

The Phentaslim Formula

Learning about each Phentaslim ingredient will show how effective the product is.

Guarana (100 mg)
Guarana is a natural caffeine source. It speeds metabolism, boosts energy, and enhances endurance, helping users perfect their workouts. Guarana also decreases calorie intake by curbing cravings. It is clinically proven to promote weight loss [1].

Caffeine Anhydrous (100 mg)
Caffeine anhydrous is dehydrated caffeine in powder form. Like guarana, caffeine anhydrous increases metabolic rate, energy, stamina, and appetite suppression.

Green Tea (100 mg)
Green tea is an all-natural antioxidant that flushes toxins and impurities from the system and protects from future invasions. This is important because these contaminants slow down the weight loss process.

Green tea is clinically proven to help users lose weight by triggering thermogenesis, suppressing appetite, and increasing metabolism [2].

Raspberry Ketone (200 mg)
Raspberry ketone is the chemical responsible for the raspberry scent and flavor. Thanks to celebrity doctor Mehmet Oz, the raspberry ketone has gained much publicity recently as a weight loss ingredient. While it is clinically proven to reduce fat levels and increase metabolism in rats, there is currently no evidence it works the same way for humans [3].

Cayenne (50 mg)
Cayenne pepper powder, is clinically proven to bring about weight loss [4]. It does so by increasing thermogenesis, which converts excess calories into heat instead of fat. This lowers the bloodstream’s fat levels. Cayenne pepper also reduces appetite.

However, the clinically tested dosage is 833 mg per day. Since the daily Phentaslim dose is only 50 mg, it probably won’t have a significant effect.

L-Tyrosine (200 mg)
L-tyrosine is an amino acid that balances hormones to make weight loss possible. Experts say L-tyrosine increases metabolism and reduces stress [5]. Low stress levels are crucial to weight loss because high stress leads to high-calorie indulgences and binge eating.

How to Use Phentaslim says, “Take 1 capsule 20 minutes before breakfast with water. Then take another capsule 20 minutes before lunch, again with water.”
The site also says, “Phentaslim does contain caffeine, so it’s best not to take late in the day. Avoid taking after 3 pm.”

Potential Side Effects

Phentaslim contains 3 caffeine-rich ingredients: guarana, caffeine anhydrous, and green tea. As a result, caffeine-sensitive users may experience the following side effects:

• Headaches
• Jitters
• Insomnia
• Anxiety
• Upset stomach

Customer Feedback

Let’s see what real users say about Phentaslim on

Carrie: “I’ve got nothing but good things to say about Phentaslim so far…I have more energy and have now started doing some nice walks every day with my mum.”

Pooja: “I started Phentaslim on 6th Dec. Not seen any weight loss yet. But I feel more energy. But since couple of days I am feeling dizziness and heavy head after consuming the medicine. The headache is quite a lot.”

Jules: “Noticed lots of energy and 2 lbs the first week, not bad start! No symptoms apart from first day when [it] took me longer to get to sleep.”

Buying Phentaslim

Phentaslim is available directly from Here are the different purchasing options they offer:

• 1 bottle: $59.95
• 2 bottles: $99.95 (free shipping)
• 3 bottles: $139.95 (free shipping)

Return Policy

Phentaslim does come with a 30-day guarantee. Users can return 1 opened bottle and any unopened bottles.

However, you have to pay a $10.00 fee in order to receive a refund. Also, even if you return the product, Optimum Nutra Inc. will keep your personal information on file. This is troublesome because they could potentially sell your information to other companies.

The Bottom Line

We have mixed feelings about Phentaslim. The product itself seems decent: its ingredients are clinically proven and generally effective, and it receives positive customer feedback.

However, Optimum Nutra Inc.’s practices are worrisome. It is difficult to find adequate information, and customers have to pay extra return fees. When you add that the company keeps consumers’ personal information on file even after cancelled orders are processed, you might think twice before purchasing Phentaslim.

Until we know more about Optimum Nutra Inc., you should try something else.


[1] Boozer, CN. “An herbal supplement containing Ma Huang-Guarana for weight loss: a randomized, double-blind trial.” International Journal of Obesity and Related Metabolic Disorders. 2001. 25(3): 316-324. Web. 18 Jan 2013.

[2] Maki KC. “Green tea catechin consumption enhances exercise-induced abdominal fat loss in overweight and obese adults.” The Journal of Nutrition. 2009. 139(2): 264-270. Web. 18 Jan 2013.

[3] Morimoto, Chie. “Anti-obese action of raspberry ketone.” Life Sciences. 2005. 77(2): 194-204. Web. 18 Jan 2013.

[4] Yoshioka M. “Effects of red pepper on appetite and energy intake.” British Journal of Nutrition. 1999. 82: 115-123. Web. 18 Jan 2013.

[5] Di Pasquale, Mauro. “An in-depth analysis of L-tyrosine.” 2003. Web. 18 Jan 2013.

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