Phentaslim is a unisex diet pill that you can only buy online. It’s an established product that has been around for quite a while. I’m writing this review in 2020 and Phentaslim is 8-years-old.

Diet pills come and go all the time. So do diet pill manufacturers. A lot of dodgy products aren’t around for long. The manufacturers peddling them make a quick buck and then go underground when bad reviews start appearing online or too many people are making complaints and crying scam.

Eight years is quite a long time and, although some customers say the product is not for them, I cannot find any complaints about Phentaslim. Everything appears to be above board and, best of all, the manufacturer provides customers with a 60-day money-back guarantee.

This is not the first time I’ve written a review for Phentaslim. I’ve written several over the years because clients used to ask me to write reviews for their sites. The formulation has not changed. The ingredients in Phentaslim are still the same. It’s a diet pill I know very well.

In all the years I’ve bee writing about diet pills I’ve never written a single negative review for Phentaslim and I’m not going to start now. It’s a good diet pill that I’m happy to recommend but that doesn’t mean it will be the right choice for you. Its suitability will depend on the areas you require most help and its ability to match your needs.

Hopefully, you will already know the kind of help you require. This review will provide you with information that will help you decide if Phentaslim is the best diet pill to give you that help.


Who Makes Phentaslim?

Phentaslim is manufactured and distributed by OptimumNutra. It’s a reputable company that also produces two other popular diet pills—Superfruit Slim and Phentatrim. Both are successful in their own right but Phentaslim beats them both as a fat burner.


Phentaslim: The Promised Results

  • Burns calories and fat
  • Improves mental clarity
  • Reduces hunger
  • Boosts Energy
  • Boosts the immune system and health
  • Improves well-being


What Does Phentaslim Do?

The ingredients in Phentaslim support weight-loss in several ways.

It Increases Metabolism and Thermogenesis

Firstly, they increase metabolism and thermogenesis. By doing these things, they cause you to burn extra calories through exercise and also make you burn more calories when you are at rest.

Due to the thermic effect they provide, some of the fat-burning ingredients may also make you feel a little warmer. By raising your body temperature slightly, they cause you to lose extra energy from your body in the form of heat.

It Reduces Hunger

If you want to lose weight you need to eat less food than normal. In fact, you need to reduce your food intake so that your body becomes so short of energy it is forced to begin burning its stores of fat. This type of low-calorie diet invariably causes feelings of hunger.

Hunger is unpleasant. It can be very distracting and weakens resolve. Some of the ingredients in Phentaslim can make weight-loss easier by helping to keep hunger under control. In my opinion, it’s hunger-crushing ability is not as powerful as that of certain alternative products but it should offer a reasonable level of support.

It Increases Energy

Diet-related fatigue can be a big problem for some people. Phentaslim can help tackle the problem by providing caffeine and other energy-boosting ingredients.

It Provides Additional Benefits

Phentaslim also contains a combination of Vitamins, amino acids, and herbs that can support the immune system and provide a greater feeling of well-being. These things are nice and may help take some of the sting out of a low-calorie and/or high-exercise regimen but you need to see them as a bonus. There are tonics and supergreens products that can do the same thing.

When you are evaluating a product like Phentaslim you need to focus on its ability to help you burn extra fat.

Things to Bear in Mind

Like other weight management products, Phentaslim is a supplement. It’s important to understand what a supplement is and never to see any form of supplement as a magic pill.

The word “supplement” refers to something you get or use in addition to something else. For instance, Some people work two jobs to “supplement” their income.

Diet pills and other weight loss supplements, supplement the efforts you are already making by controlling your diet.

In this case, it’s important not to see Phentaslim as a product that provides an excuse not to try and eat healthy foods. The pills will work best if you use them alongside a healthy diet that contains nutritious foods that are low in fat and sugar.


Phentaslim: List of Ingredients

Three capsules per day provide:

Amount Per Daily Serving % NRV
Korean Panax Ginseng (40:1) 1,200mg
Guarana Extract (4:1) 400mg
Green Tea (15:1) 375mg
Caffeine Anhydrous 270mg
L-Theanine 225mg
N-Acetyl L-Carnitine 200mg
L-Tyrosine 200mg
Ginkgo Leaf Extract 120mg
Magnesium 80mg 21%
Cayenne Powder (8:1) 50mg
Black Pepper 24mg
Niacin (Vitamin B3) 20mg 125%
Zinc 15mg 150%
Vitamin B6 1.8mg 129%
Riboflavin (Vitamin B2) 1.3mg 93%
Thiamine (Vitamin B1) 1.3mg 118%
Vitamin B12 10mcg 400%

How Good is Phentaslim?

This is the part of the review where we take a closer look at ingredients and see if they can enable Phentaslim to provide the kind of results OptimumNutra is promising.

The Phentaslim formulation contains 17 ingredients so this is going to be quite a long review.

When you look at some of the ingredients, you will see numbers in brackets and be curious about what they mean, so let me explain.

In the case of Korean ginseng, for instance, OptimumNutra is using a “40:1” extract. That means the extract is concentrated to be 40 times more potent than the standard ingredient. Rather than use 1,200mg of standard ginseng, the company is using 30mg of a super-potent form (40×30 = 12,00).

Using extracts with enhanced potency allows manufacturers to create very powerful products without causing the pills to become too big and bulky to swallow.

Okay, let’s take a look at the 17 ingredients and what they can do.


Korean Ginseng (40:1) 1,200mg

Korean ginseng is a popular Chinese herb that has several other names including Panax ginseng and red ginseng. Although there are other types of ginseng, Korean ginseng is known to be the most potent type.

Most people have heard of ginseng due to its reputation as an aphrodisiac. A lot of people are also aware of its ability to invigorate the body and improve overall mental and physical health.

If you are interested in learning more about ginseng’s ability to support good health, here’s a link to a study you may want to read: Ginseng, the ‘Immunity Boost’: The Effects of Panax ginseng on Immune System

Although OptimumNutra does not make any claims about ginseng and weight loss, certain research suggests it has potential value in this area too: Ginseng and Obesity


Guarana Extract (4:1) 400mg

Guarana is a tropical berry that’s used in many different types of supplements. You can also buy guarana energy drinks.

Guarana provides caffeine. It’s a potent source but it releases caffeine slowly. This allows it to provide long-lasting stimulation.

Caffeine is good for boosting energy. It also helps clear the mind and is known to be a mild appetite suppressant. In addition to these abilities, caffeine is also a proven fat burner.

Research shows caffeine boosts your bodies natural fat burning capabilities by increasing metabolism and thermogenesis: (Caffeine: a double-blind, placebo-controlled study of its thermogenic, metabolic, and cardiovascular effects in healthy volunteers)


Green Tea (15:1) 375mg

Green TeaGreen tea is a very popular diet pill ingredient and, due to the potent antioxidants (green tea catechins) it provides, green tea is very good for the health. In fact, it’is known to be one of the healthiest beverages in the world. By fighting free radical toxins it helps reduce oxidative stress and helps prevent disease.

There’s a mountain of evidence that shows green tea also boosts metabolism and thermogenesis. The results of one study are particularly notable because they suggest green tea may keep on providing its benefits for up to 24 hours. (Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans)


Caffeine Anhydrous 270mg

Caffeine anhydrous is a highly concentrated form of caffeine. Unlike guarana, it delivers caffeine to the body quite fast.


L-Theanine 225mg

L-theanine is an amino acid that’s present in green tea. It acts on the neurotransmitters that are responsible for governing the mood and is valued for its ability to relax the mind without causing sedation. The effect it offers is sometimes called an alert state of calm.

L-Theanine and caffeine have an interesting synergy. For that reason, the two ingredients are often blended together. When combined, they are known as “smart caffeine” because L-theanine enhances the effects of caffeine while also reducing the likelihood of negative issues like jitters and headaches or the dreaded “caffeine crash”. (The effects of L-theanine, caffeine and their combination on cognition and mood)


N-Acetyl L-Carnitine 200mg + L-Tyrosine 200mg

Both these ingredients are amino acids you can find in many bodybuilding supplements. As well as assisting muscle growth, they support increases in physical stamina.

Individually and together, the two ingredients also boost fat metabolism.


Ginkgo Leaf Extract 120mg

Ginkgo biloba is a species of tree. The ingredient in supplements generally comes from the leaves.

Ginkgo biloba is an excellent source of antioxidants and is often used as a natural remedy for inflammation. The ingredient is unlikely to directly support weight-loss but it can help improve circulation and offers protection from anxiety and depression. However, experts say further study is required (Ginkgo biloba as an Alternative Medicine in the Treatment of Anxiety in Dementia and other Psychiatric Disorders)


Magnesium 80mg

Magnesium is a mineral the body uses in many different ways. OptimumNutra has chosen to add it to Phentaslim because of its ability to support optimal muscular function [LEARN MORE]


Cayenne Powder (8:1) 50mg

Red Chili PeppersCayenne pepper/capsicum is a good ingredient for a diet pill such as this one. The capsaicin it provides supports weight loss in a couple of ways.

The first thing capsaicin does is suppress hunger. (Effects of red pepper on appetite and energy intake)

However, cayenne is generally mostly favored for its ability to promote fat loss by increasing metabolism and thermogenesis. (Acute Effects of Capsaicin on Energy Expenditure and Fat Oxidation in Negative Energy Balance)


Black Pepper 24mg

Black pepper provides piperine. It’s an alkaloid that helps the body absorb other ingredients. It aids nutrient absorption too.

Some research suggests piperine is a fat burner as well but supplement manufacturers generally favor it as a bioavailability enhancer.


Zinc 15mg

Zinc is a versatile mineral that aids wound healing and helps keep the immune system strong. It’s also a good natural testosterone booster and, for that reason, it’s often added to bodybuilding supplements and male enhancement formulations. (Zinc status and serum testosterone levels of healthy adults)

As you are probably aware, testosterone supports muscle growth. Many dieters find they lose muscle mass during their diets. The fact that Phentaslim provides the body with extra zinc may help prevent loss of muscle mass from becoming an issue.

Testosterone also helps the body to burn fat so zinc is a worthy inclusion in several different ways.


Vitamin B6 1.8mg

Vitamin B6 aids energy metabolism. It’s a trait all B vitamins share. The next time you buy an energy drink, look at the back of the can. You’ll find several B vitamins listed there.

As well as aiding energy metabolism, Vitamin B6 helps the body make the hemoglobin the red blood cells need to carry oxygen around the body.


Riboflavin (Vitamin B2) 1.3mg

As well as helping your body release energy from food, riboflavin is good for the skin and eyes. It also helps keep your nervous system healthy.


Niacin (Vitamin B3) 20mg

Niacin causes vasodilation. This improves circulation and helps the organs and muscles benefit from a better supply of oxygen and nutrients. When you get too much niacin it can cause a flushing sensation known as niacin flush. (Does nicotinic acid (niacin) lower blood pressure?)

It’s not unusual for people to take therapeutic doses of niacin of 1,000-2,000 mg. The amount provided here is so low niacin flush is highly unlikely.


Thiamine (Vitamin B1) 1.3mg

Another B vitamin that’s good for the nervous system and helps you to get energy from your food.


Vitamin B12 10mcg

One more energy-boosting B Vitamin to add to the mix. When you don’t get enough of this one it can cause anemia. There are no plant-based sources of Vitamin B12, so vegans and vegetarians need to rely on supplements and fortified foods. (Vitamin B12 – The Vegan Society)


How to Use Phentaslim

Bottle Vegan-Friendly PhentaslimOptimumNutra states you can take 2-3 capsules per day, but 3 capsules per day appears to be the standard dose. When you are taking three capsules per day, each bottle of Phentaslim will last for a month.

You don’t take the capsules all at once and it’s important not to exceed the 3 capsules per day.

Take the first capsule just before breakfast and the second one before eating lunch. You take the third capsule just before dinner and each dose needs to be taken with a full glass of water.

If you are sensitive to caffeine, OptimumNutra suggests beginning with only one capsule per day and only increasing the dose if no tolerance issues occur. The company also warns against taking Phentaslim after 5 pm.


Words of Wisdom:

If you are pregnant or nursing a child, please don’t take any kind of supplement without getting clearance from your doctor first.

If you have an existing medical condition of any kind at all, it would also be unwise to use supplements without checking with your doctor first.

Certain supplement ingredients can present interaction issues when combined with medication. It doesn’t matter if the medication has been prescribed by a doctor, a dentist, or another medical professional. If you are taking medication, don’t use it with supplements without asking a doctor first.

*Information on the Diet Pill Ninja website is not intended to be a substitute for professional medical advice.


Does Phentaslim Have Honorable Customer Reviews?

There are a few nay-sayers but Phentaslim good customer reviews far outnumber the bad.

A couple of 5-star reviews:

Phentaslim Positive Customer Reviews

A couple of negative reviews:

Negative Phentaslim Reviews from Customers

It’s never confidence-building to see negative reviews. However, when I see comments like the ones above, I tend to start shaking my head.

If these people had really been making the right efforts with diet and exercise they would have lost weight without using any supplements at all. Phentaslim is a good diet pill that can help you to lose extra weight but it won’t do all the work for you. There are no magic pills.


Does Phentaslim Cause Side Effects?


Phentaslim contains caffeine. If you are unusually sensitive to stimulants, you may want to consider an alternative option instead.

However, if you can drink 3 cups of coffee per day without any problems you should be okay with Phentaslim.

Three capsules per day provide 270 mg of caffeine. The presence of guarana and green tea will add a little more so you are probably looking at around 300 mg of caffeine. You need share that by three because you only take one capsule at a time.

In reality, you will be looking at around 100 mg of caffeine per 1-capsule dose. That’s about the same amount you would get from a standard cup of coffee. If you don’t normally have a problem drinking coffee, you should be okay with Phentaslim and, let’s not forget, the formulation also contains L-Theanine, which reduces the risk of caffeine-related side effects.

As you are probably aware, caffeine can do this to certain individuals if they consume it too late in the day. As a rule of thumb, it’s best to leave a gap of at least five hours between consuming caffeine and going to bed.

It’s also a good idea to avoid taking products like Phentaslim alongside other sources of caffeine, such as tea, coffee, cola, and energy drinks.


The Best Place to Buy Phentaslim

OptimumNutra has created a special Phentaslim website. It provides a wealth of information about the product and is also the best place to go if you want to buy Phentaslim online.

Each bottle contains a 30-day supply of pills and the normal price is $69 per bottle. However, OptimumNutra generally often runs promotions that provide considerable discounts. At the time of this review, it was possible to buy a bottle of Phentaslim for $49 (£39).


Customers who want to get more bang for the buck can do so by taking advantage of the opportunity to get three bottles of Phentaslim for the price of two of five bottles for the price of three.

OptmumNutra never applies shipping charges. The price you see on the Phentaslim website is always the price you pay and customers get a free ebook to help them maximize the amount of weight they lose in a month.

4-Week Fat Blast (Free ebook with Phentaslim


After the Sale (What Happens Next?)

Customer Service

The only way to contact customer services is to submit a support ticket by filling in an online form. That’s not great if you are the type of person who likes to deal with queries over the phone but a system like this is very efficient and probably makes it easier for the customer support team to handle queries more quickly.

Guarantee and Product Returns

OptimumNutra provides a 60-day money-back guarantee. The guarantee period begins on the day you order the pills. If the guarantee period was 30-days instead of 60, that may be an issue because you would not have time to use a full bottle and see what Phentaslim can do. With a 60-day guarantee, there is no problem. You can the pills for a month and still have plenty of time to play with if you are not happy with the results.


Phentaslim Review: Diet Pill Ninja Conclusion

The Diet Pill Ninja: Honorable Diet Pill ReviewsI have a lot of respect for this product and am happy to recommend it to most people who need help to lose weight. However, if you normally have an unfavorable response to caffeine, I suggest you chose something else instead.

A lot of customers report having great success with this product, given the quality of the fat burning ingredients it contains, that’s not surprising. It’s also nice that OptmumNutra provides a money-back guarantee.

Due to the presence of B Vitamins and caffeine, Phentaslim may be a particularly good option for men and women who are training hard at the gym or doing other sporting activities to help them lose weight. B-Vitamins and caffeine are often combined in energy drinks and not without good reason. Phentaslim will also offer good benefits to anyone prone to diet-related fatigue.

However, although the formulation contains ingredients that can help reduce hunger, it has are more potential as a fat burner.

If you are primarily looking for something that can keep your appetite under control, you may be better off choosing a good glucomannan product. I suggest OptimumNutra’s other product, Phentatrim. It’s a good appetite suppressant and, like Phentaslim, it has a 60-day money-back guarantee.

However, if you are most interested in speeding up your fat loss and hunger is not your main issue, stick with Phentaslim.

Click HERE to get up-to-date price information on Phentaslim


Some FAQs

Is Phentaslim suitable for vegetarians and vegans?

Yes. Although the original product (red capsules) has gelatin in the casing, in August 2020, OptimumNutra changed the casing and made it gelatin-free. Although the ingredients in the capsule are the same the casing is not. The new vegan-friendly casing is clear instead of red.


Do I need to use Phentaslim with diet and exercise?

Yes. Taking a diet pill is not like waving a magic wand. Phentaslim is designed to assist the efforts you make with diet and exercise, not replace them. If you are looking for a product that will make the need for effort disappear, your quest is going to leave you disappointed. (Why Diet Is More Important Than Exercise)


Is it safe to use Phentaslim during pregnancy?

It would be unwise to Phentaslim during pregnancy. Equal caution will be necessary if you are breastfeeding a child.

Ninja Sword