Watchdog Approved Diet Pills


FenBurn is a diet pill described as a powerful thermogenic, which supposedly contains “very high levels of ingredients”. Is FenBurn the great fat burner that it claims to be, or is it just another generic diet pill with almost identical ingredients to many of its competitors?

Fenburn Pros

  • Some useful ingredients
  • Vegetarian friendly capsules

Fenburn Cons

  • May interact with other medications
  • Side effects likely
  • No money back guarantee
Watchdog Rejected Diet Pills

Fenburn Review

Fenburn Facts

  • Sold by Ltd
  • 90 capsules per bottle
  • Website littered with spelling mistakes and typos

FenBurn is sold by Ltd, although it seems that they are not the manufacturers, stating on their ‘Our Guarantee’ page that all of their products are “are sourced directly from either the manufacturer or an officially approved distributor”. do not advertise who the manufacturers of FenBurn are. It is easy to contact, as they provide an address, telephone number and email address, clearly displayed at the bottom of their website.

Slimming PlusOrdering from grants the customer access to Slimming+, a weight loss community that features web forums, recipes and meal plans, workout plans and exercises, and fitness and dietary trackers that are easy to use. Whilst this is a great bonus feature, other websites offer similar services for free, without having to make any kind of purchase. Rather than buy a product just to get access to this portion of the site, we recommend visiting, or downloading the My Fitness Pal App.

The sales page for FenBurn is littered with spelling mistakes, and also contains some inaccurate descriptions of the product. For example, the product is described as being a “high powerful antioxidant”. Two of the ingredients, Oolong tea extract and Green tea extract, do contain antioxidants, but we find this description to be misleading. Whilst this may sound like a trivial detail to point out, it is never reassuring to realise that the company may not entirely understand their own product.

There are some side effects that are associated with the use of individual ingredients that are used in FenBurn, and yet claims that there are no side effects associated with FenBurn. Users are recommended to not consume FenBurn after 3pm, as this can interfere with sleep patterns.

FenBurn writes that;

If you can keep your metabolic rate high, your body will burn up more fat, even when you’re resting, it really is that simple. Take FenBurn and you’ll know you are forcing your body to continually burn up unwanted fat.

FenBurn are oversimplifying the whole process of weight loss, which is actually a very complicated balance of numerous different processes in the body. However, what we really disagree with is the claim that FenBurn will continually burn up fat. Depending upon the body’s energy needs, and when the food was last consumed, stored fat and other sources of fuel in the body are used at different times. The active ingredients in FenBurn in general only stay in the body for a few hours at a time, and so their weight loss boosting potential is limited.

One small point that may appeal to some customers is that the capsules are suitable for vegetarians, being based upon cellulose rather than the usual gelatine.

Fenburn Concerns:

  • Numerous possible side effects and possible interactions with medications
  • Unknown ingredient amounts
  • No money-back guarantee

What Does Fenburn Claim To Do?

FenBurn Fat Burners supposedly:

  • speeds up the metabolism
  • burns fat effectively
  • boosts energy

The website also claims that it is a highly powerful antioxidant, with no side effects, and describes the product as the websites most powerful fat burner.

So What Is Fenburn and What Are The Ingredients For Fenburn?

There are numerous ingredients present in FenBurn, which are primarily aimed at increasing the metabolism and the body’s fat burning ability.

There is no information available on how much of each ingredient in present in FenBurn, other than the assurance that it is formulated with “very high levels of ingredients”. In addition to the ingredients promoted as active ingredients on the sales page, the product also contains vitamin C, and several other B vitamins. B vitamins play various roles in the body, and are often linked to various stages of energy release from food as well as from cells in the body.

  • Bitter orange peel: Also known as citrus aurantium, this ingredient contains synephrine. A review of numerous studies concluded that use of synephrine resulted in an increase to the participants resting metabolic rate and energy expenditure, and moderate weight loss was seen in studies lasting over 6 weeks. However, there are some concerns about its safety being under-researched and the numerous side effects that have been associated with it.
    Source: /
  • Green Tea Extract: Green tea is high in a group of antioxidants called catechins. Studies have suggested that catechins and caffeine both increase energy expenditure by boosting the metabolism temporarily. However, the metabolic increase caused by green tea is limited. One study found that the use of green tea was not enough to counteract weight gain following a very low calorie diet.
  • Oolong Tea: Oolong tea is a partially fermented tea made from the same plant that black and green teas are made from. Studies have suggested that the caffeine and antioxidants found in Oolong tea improve lipid metabolism in the body, and that chronic consumption of oolong tea could decrease body fat content and reduce body weight by a small amount.
  • Capsaicin: Capsaicin, found in Cayenne pepper, is thought by some to play a role in weight loss. Some studies suggest it could suppress the appetite mildly, whilst others suggest that the heat causes a thermogenic reaction in the body, burning more calories for a period of time. However, there are also studies that show cayenne has little or no effect upon weight loss attempts.
  • Caffeine: Numerous studies have shown that caffeine boosts energy levels and alertness, as well as mildly boosting the metabolism, causing a small increase in the number of calories used by the body. The effects shown in studies are small, and some studies are inconclusive.
    Source: /
  • L-Tyrosine: An amino acid that is a building block of protein, this ingredient is found naturally in many foods including meat and dairy products. Some people use it as an appetite suppressant, but there is little evidence that it is effective for this use. Large doses of tyrosine may be useful for increasing alertness, especially in people who are sleep deprived.
    Source: WebMD Resource
  • Vitamin B12: Vitamin B12 is naturally present in many foods, primarily meat, fish and dairy products. It has several roles, including aiding in releasing energy from consumed food, and keeping the nervous system healthy. It may be that a deficiency hinders weight loss, but taking excess amounts could be, according to the NHS, potentially harmful.
  • Bioperine: This patented Black pepper extract is used for increasing the bioavailability of nutritional compounds. In other words, it increases the amounts of nutrients that are absorbed into the body in the digestive tract. It may also increase the absorption of various drugs, which may lead to potential side effects.

So What Does All This Mean?

FenBurn has numerous ingredients that may have small effects upon the body’s fat burning ability, and so may increase weight loss for those who are already on a calorie controlled diet. However, without knowing how much of any individual ingredient is present in FenBurn, it is impossible to compare the diet pill with any relevant studies that look at the individual ingredients. FenBurn seems to have some potential for aiding weight loss and boosting energy, but how effective it could be is currently unclear.

Does Fenburn Have Any Side Effects?

Whilst the makers of FenBurn state that there are no side effects associated with the use of FenBurn, we have found that several of the ingredients have been linked with various side effects.

The Mayo Clinic has recommended avoiding Bitter orange extract as a weight loss aid,

because bitter orange can cause a range of potentially serious health problems.

These include increased heart rate and blood pressure, fainting, heart palpitations, heart attack, and stroke. These have been reported even in healthy people using the ingredient, but the risk increases even further for those who are overweight or obese, or those who already have high blood pressure.

The effects of bitter orange extract are magnified when combined with caffeine, as it is in FenBurn. Caffeine also has its own set of side effects, including headaches, jitteriness, raised blood pressure, increased urination, dehydration, heart palpitations and insomnia.

Bioperine may interact with some medications, and can increase the amount of other drugs that gets absorbed into the bloodstream. This could potentially lead to an increased risk of developing side effects from other medications, or even causing an overdose. It is recommended that people who are already taking medications avoid use of Bioperine and diet pills that use Bioperine, including FenBurn.

The product contains several different ingredients that act as natural stimulants, which boost the energy levels of the user. However, this means that sleep can easily be interrupted if a tablet is consumed too late in the day. It is recommended by the seller that FenBurn is not taken after 3pm, to minimise sleep disturbances.

Caution: Avoid if you are pregnant or breast-feeding.

Any Fenburn Reviews From Customers?

On, the website that sells FenBurn, there are a few reviews. However, other than this, customer feedback is incredibly limited for FenBurn.

One customer had some success with their weight loss, but had hoped for better results, writing:

Just finished my first pack and since taking I have only lost 3lbs It’s better than nothing I guess! I was hoping for more but it’s definitely given me more energy anyway so buying another month and will report back again soon.

Another customer wrote that they lost 2% body fat in 2 weeks, but does not say how much weight that figure actually represented. His muscle mass did not decrease, and apparently the pills “boost your energy massively”. The reviewer noted that the results from his latest cutting stage were the best he has achieved, which he attributed to FenBurn:

During my cutting stage I eat pretty much as normal but cut down on sugar and add 20 minutes extra cardio to my workouts. Losing over 2% body fat whilst maintaining my full muscle mass is my best to date! I can only put this down to Fen Burn as I didn’t change anything else from what I normally do.

So Does Fenburn Work?

It seems that FenBurn may help to marginally increase the rate of weight loss for people who are already dieting and exercising. However, it is unlikely to live up to the claims made about it on the main sales page. It is not possible to tell accurately how well FenBurn works, if at all, because of the lack of clarity about the quantities of each ingredient. It may be that in the few reviews posted, the customers lost weight because of other factors.

Where Can I Buy Fenburn?

FenBurn can be bought exclusively from There are a wide range of price discounts available for those who want to purchase more than one bottle of the product at a time. One bottle costs £34.00, whilst 6 bottles costs £24.99 per bottle. have distribution centres in both the UK and the USA, meaning that postage costs are lower than for many other distributers, who are based in only one country.

What About A Guarantee offer no money back guarantee, but have their own guarantee of the service a customer can expect from them. The full guarantee mentions nothing about returning products.

Watchdog Verdict

There are both good points and bad points to be made about FenBurn; the few customers who have reviewed FenBurn have reported weight loss and significant boosts in energy, but there are still surprisingly few reviews considering that the product has been on the market for several years now. It is not possible to tell if these results are due to the use of the diet pill or other factors.

The lack of ingredient quantities, or an amount of proprietary formula per tablet make it incredibly hard to establish how effective the product is, especially in relation to clinical trials. In any regard, many of the trials that feature Oolong tea or green tea used amounts much greater than could be feasibly placed in a few capsules. For example, one oolong tea study used 8 grams a day. It is likely therefore that the results expected should be less impressive than the results of these studies.

The guarantee offered by is not a money back guarantee, and does not mention returns at all. Instead it is an explanation of the level of service that promise their customers, at least in relation to sales. Whilst this is refreshing to see, the addition of a money back guarantee would be better in our eyes.

Finally, the biggest factor in our decision to reject FenBurn is the possibility of side effects, despite the claims made that this is a side effect free diet pill. Not only are there several different stimulants, which all carry the risk of increased blood pressure, heart palpitations and more severe cardiac related problems, but there is also the risk of Bioperine interacting with any other medications that are being taken at the same time as FenBurn.

Watchdog Rejected Diet Pills

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Disclaimer: Our reviews and investigations are based on extensive research from the information publicly available to us and consumers at the time of first publishing the post. Information is based on our personal opinion and whilst we endeavour to ensure information is up-to-date, manufacturers do from time to time change their products and future research may disagree with our findings. If you feel any of the information is inaccurate, please contact us and we will review the information provided.

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2 comments to “Fenburn”

Like to leave comment?

  1. says:

    Thank you for reviewing our product.

    We would like to confirm that we do have a 30 day money back guarantee on the product, which is given below:

    If you’re not completely happy with your purchase simply return it within 30 days for a full refund or exchange. That’s our satisfaction promise to you.

    We are currently changing the terms and conditions on our website to allow clarity to the entire store, but we always stand by our above statement, that we have a 30 day money back guarantee.

    Our re-order rate on the product is very pleasing, and customers have consistently given positive reviews about our product. We would be happy to answer any further questions on the product.

    • Watchdog Team says:

      Thank you Rob for being proactive and responding so promptly to our review.
      We would like to know more about the money-back guarantee though as we are unable to locate this on your current website. Does the money-back guarantee apply to open or unopened bottles and when does the guarantee start?
      Thanks again for responding so quickly.
      Diet Pills Watchdog Team

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