Instant Knockout Reviews In 2023: Is It Worth The Money?

Lindsey Desoto

Updated on - Written by
Medically reviewed by Kathy Shattler, MS, RDN

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Instant Knockout




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  • Contains glucomannan, which may suppress appetite.
  • Includes caffeine for an energy boost.
  • Contains ingredients that may help with fat loss.
  • All natural ingredients.
  • No proprietary blends.
  • May help boost metabolism.

Brand Information

  • Founded in 2014.
  • Owned by Roar Ambitions.
  • Founder is Robert Parker.

Medical Benefits

  • May help suppress appetite.
  • Can help increase metabolism slightly.
  • May help with fat loss.

About The Brand

Roar Ambition is a sports nutrition company founded in 2014 by a digital marketing entrepreneur named Robert Parker. The company prides itself on using all-natural, high-quality ingredients to produce its supplements, which are made in the United States and the United Kingdom.

Roar Ambition owns several well-known brands on the market, including Testo Fuel, Prime Male, and Instant Knockout.

This article looks in-depth at Instant Knockout, one of Roar Ambition’s most popular fat burners, to determine whether it lives up to its hype. Read on to learn more about Instant Knockout reviews.

What Is Instant Knockout?

Created in 2014, Instant Knockout is a popular weight loss supplement that promises to speed up fat-burning while allowing users to maintain muscle mass.

Although anyone looking to lose weight can use Instant Knockout, the product is heavily marketed toward mixed martial arts or MMA fighters and boxers who need to lose weight before a fight.

In fact, the supplement is even used and endorsed by professional mixed martial arts fighters like Diego Sanchez and John Dodson.

Is It Safe To Use Instant Knockout Fat Burner?

Like many other dietary supplements, Instant Knockout has not been approved by the Food and Drug Administration for safety and effectiveness.

However, we are impressed that Instant Knockout is made with natural ingredients and doesn’t use sketchy proprietary blends like many other fat burners. The company lists all ingredients and dosages for full transparency.

Overall, Instant Knockout seems to be safe for most healthy individuals. However, as a stimulant fat burner, it is relatively high in caffeine and may not be ideal for those with caffeine sensitivity. Additionally, even natural ingredients have the potential to interact with other medications you are taking. 

It is also important to note that Instant Knockout is not considered safe for pregnant or breastfeeding women and children.

Always consult your healthcare provider to determine if a dietary supplement is safe for you to take.

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Instant Knockout reviews

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Instant Knockout

  • Contains glucomannan, which may suppress appetite.
  • Includes caffeine for an energy boost.
  • Contains ingredients that may help with fat loss.
  • All natural ingredients.
  • No proprietary blends.
  • May help boost metabolism.

Does It Really Work?

Over the years, the Instant Knockout formula has undergone several tweaks to improve its effectiveness and transparency of ingredients.

The most recent version, Instant Knockout Cut 2.0, contains high doses of glucomannan and green tea extract to help suppress appetite and provide a natural thermogenic boost.

Thermogenic supplements are intended to boost the metabolic processes that naturally burn fat in your body.

Of course, there is no magic pill for weight loss. There are no supplements that are going to increase your daily calorie burn substantially. However, Instant Knockout contains clinically proven fat-burning ingredients that can deliver weight loss results when paired with a healthy diet with a calorie deficit and regular exercise.

Many supplement companies stand behind their products, offering a money-back guarantee if their product doesn’t produce results. However, the return policy set forth by Instant Knockout is strict. Only unused, unopened products can be returned within 30 days.


  • Contains ingredients scientifically proven to aid in fat burn.
  • May help suppress appetite.
  • Contains all-natural ingredients.
  • It may boost your energy levels.
  • Vegan-friendly.
  • Designed for men and women.


  • Lacks third-party testing.
  • May not be ideal for caffeine-sensitive individuals.
  • Pricey.
  • Must take four pills at different times of the day.

Instant Knockout Ingredients

Instant Knockout features a blend of nine natural ingredients, including glucomannan, an appetite suppressant, and potent thermogenic such as cayenne pepper seeds and green tea extract. These ingredients help tap into stored fat and support weight loss.

This supplement also contains a relatively high amount of caffeine to boost energy and l-theanine to smooth out the caffeine jitters and prevent crashes. Lastly, Instant Knockout provides 225% of the Daily Value of vitamin D per serving. Increased vitamin D levels[1] are associated with better sports performance and a reduced risk of injury. About one billion people globally are deficient in vitamin D,[2] and a full 50% are insufficient.

Instant Knockout Ingredients

Here’s a detailed look at the most significant ingredients in Instant Knockout.


Glucomannan is a dietary fiber that comes from the root of the konjac plant. It may help with appetite suppression and body weight regulation if taken before eating a meal. There’s also some evidence[3] that glucomannan may help reduce total cholesterol, LDL — or bad cholesterol —  and fasting blood sugar in people with type 2 diabetes.

One 2023 randomized control trial[4] found that consuming gummy candies enriched with 250 milligrams of Konjac glucomannan improved waist circumference and hunger after 14 days.

Glucomannan may work by absorbing water and expanding in the gastrointestinal tract, helping create a feeling of fullness or satiety. 

Cayenne Pepper Seeds

Cayenne pepper seeds contain a powerful, unique compound called capsaicin, which can increase the number of calories your body burns each day and suppress fat accumulation. 

While further studies are needed, capsaicin is believed to work by increasing body temperature and oxygen consumption,[5] resulting in a slight increase in the number of calories you burn.

One 2017 study[6] noted that consuming a capsule containing 2 milligrams of capsaicinoids led to participants burning 116 calories more per day than those who consumed the placebo.

Of note, Instant Knockout does not specify the amount of capsaicin in their product. Therefore, we don’t really know how much is present.

Green Tea Extract

There are many proposed mechanisms behind green tea’s potential to improve body composition. 

For example, the compounds found in green tea may aid in weight loss[7] by reducing food intake and fat absorption. Green tea may also increase energy expenditure through heat production from fat breakdown.

It seems that the catechin and caffeine content[7] in green tea plays a large role in its weight loss benefits.

One 2020 study[7] examined the benefits of 500 milligrams of green tea extract daily for eight weeks on 30 overweight females. Researchers found that green tea extract improved exercise‐induced body composition by further reducing changes in body weight, body mass index, waist-to-hip ratio, and body fat percentage. Furthermore, combining exercise and green tea extract may produce more significant changes in anti-inflammatory markers that are associated with obesity[8] and muscle fatigue[9] than exercise alone.


Most of us are familiar with caffeine’s ability to give us a boost of energy. However, caffeine may help improve our body composition and make losing weight slightly easier.

One 2019 review of studies[10] concluded that increased caffeine consumption could decrease body weight, body fat, and overall body mass index.


L-theanine is an amino acid derived from tea leaves that may improve cognitive performance[11] and help calm you.[12] Combining L-theanine with caffeine may help offset the jitteriness of caffeine. 

Vitamin D3

Vitamin D[13] is vital for good health. In addition to aiding in calcium absorption, your muscles need vitamin D to move, and your immune system needs it to fight viruses and bacteria. Suboptimal vitamin D status can increase the risk of impaired muscle function, stress fractures, and acute illness.

Instant Knockout contains 1,800 International Units of vitamin D, triple the recommended daily amount for healthy adults under 70.

Because vitamin D is a fat-soluble vitamin, it is stored in the body for long periods and poses a greater risk for toxicity. However, the toxic effects of too much vitamin D[14] may be seen even if blood levels do not rise in accordance with the supplementation. Effects such as hypercalciuria, hypercalcemia, and high phosphate levels indicate calcium and phosphorous dysregulation and may occur with too much vitamin D.

However, the amount of vitamin D is unlikely to cause toxicity if your total dietary vitamin D intake from all sources is less than 4,000 IU.[15]

Vitamin B6

Vitamin B6[16] is important for energy production. It can also help increase brain serotonin and dopamine levels, boosting mood and decreasing anxiety, fatigue, and pain.

Instant Knockout contains 294% of the DV for vitamin B6. However, its vitamin B6 content is still way under the established upper limit[17] for adults, which is 100 milligrams.

One 2022 review of studies[18] noted that high-dose vitamin B supplementation might help reduce self-reported symptoms of depression and anxiety.

Vitamin B12

Vitamin B12[19] is important for many aspects of health, including red blood cell formation, energy metabolism, and mood regulation.

Most people in the U.S. meet their daily vitamin B12 needs through diet. However, those with diets very low in animal products or who follow a vegan or vegetarian diet may be at risk of deficiency. Those who follow a vegan diet should always take a B12 supplement.

Instant Knockout contains 417% (10 micrograms) of DV for vitamin B12. Currently, there are no reports of adverse effects[20] associated with vitamin B12, even when consumed at high doses.

Black Pepper Extract

Black pepper contains piperine, which is often added to dietary supplements to increase the absorption[21] of various nutrients.

There is some evidence[22] to suggest that piperine may support weight management by preventing the absorption of fatty acids, resulting in a decrease in body fat. It may also enhance intestinal barrier function.

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  • Contains a proprietary blend.
  • Lacks third-party testing.


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Health Benefits Of Instant Knockout

Instant Knockout features a combination of science-backed ingredients that can support your health and fitness goals. 

While it’s important to maintain realistic expectations and recognize that there are no miracle solutions, incorporating Instant Knockout into a healthy diet and exercise routine may provide the following benefits:

  • Metabolic boost.
  • Appetite suppression.
  • Energy boost.
  • Better bone health.

Potential Side Effects

Instant Knockout has a high caffeine content, with 300 milligrams per serving. It also contains green tea extract, which is also high in caffeine.

According to the FDA, most healthy individuals can consume up to 400 milligrams[23] of caffeine daily without experiencing any adverse effects.

However, some people may be sensitive to caffeine and experience the following side effects:[23]

  • Upset stomach.
  • Nausea.
  • Anxiousness.
  • A feeling of unhappiness.
  • Insomnia.
  • Headache.
  • Fast heart rate.

Lastly, always check the ingredients list to ensure your weight loss supplement does not contain any ingredients you have an allergy or intolerance to.

How To Take Instant Knockout

According to the company, users of Instant Knockout should take one capsule with a glass of water four times daily. 

The first capsule should be taken soon after waking up, the second one in between breakfast and lunch, the third one should be taken one hour after lunch, and the fourth one taken one hour before your evening meal. Your last dose should not be taken within five hours of bedtime.

For optimal results, the company recommends taking Instant Knockout at the following times:

  • 8 a.m.
  • 11 a.m.
  • 2 p.m.
  • 5 p.m.

Instant Knockout Review: What Do Real Users Say?

Overall, Instant Knockout has an average score of 3.6 out of a 5-star on Trustpilot. Most customer reviews are either very positive or very negative. Most of the negative reviews are from customers who reacted to specific ingredients or experienced difficulties with customer service.

Here’s a look at Instant Knockout Fat Burner Reviews from actual users.

Using system Cut + Complete almost two months. Also, as a bonus for purchase, I received a Hunter t-booster. Just one word – AWESOME! The only con is that premium quality is quite expensive but with affordable special offers. Highly recommended!


Roar Ambition, the seller, should be held accountable for misleading returns information. After the very 1st tablet, I developed a headache, my stomach was upset, and I had no energy (nothing other than water was consumed, and no other supplements were taken). Four days into the program, the headaches left me feeling very ill, and the company refused to refund me despite the unsuitability of the product. Poor service, misleading information, and false advertising. Roar Ambition will make any excuse possible to avoid taking responsibility for poor-quality products. This is not an authentic product.


Great fat burner, but be careful. I took these with a low-calorie diet and exercise and lost three stones, or about 42 pounds, in 3 months. Stopped taking them to stabilize weight.


Final Thought

Instant Knockout is a fat loss supplement developed by Roar Ambition. Fitness enthusiasts of all skill levels can consume it. However, it primarily targets MMA fighters and boxers who need to shred unwanted body fat before a competition.

The supplement contains ingredients that have evidence to support their ability to increase energy, boost metabolism, and aid in fat burn. Although it may be helpful in your weight loss journey, results will be unlikely without proper diet and exercise.

If you are looking for a decent-quality fat burner and are not sensitive to caffeine, try Instant Knockout. If you are sensitive to caffeine, it’s best to avoid it and opt for a non-stimulant fat burner.

As always, it is recommended to consult with a healthcare provider before making any changes to your diet or supplement regimen.

Frequently Asked Questions

Is it FDA-approved?

No. Like all dietary supplements, Instant Knockout is not approved by the Food and Drug Administration. It is, however, produced in the USA and the U.K. to the highest possible standards in FDA-registered facilities and approved by the Greater Manchester Combined Authority. 

Do I have to exercise while using Instant Knockout?

While the supplement is intended and encouraged to be used by those who exercise, you can use Instant Knockout without exercising.

Do I have to be an athlete to use Instant Knockout?

No. Men and women of all fitness levels can use instant Knockout.

How long will it take for Instant Knockout to work?

It varies from person to person. You can expect to notice results within three to four weeks of consistent use.

Can you buy Instant Knockout from local stores?

No. You can only purchase the supplement from the official Instant Knockout online store.

Does Instant Knockout work?

Instant Knockout contains clinically proven ingredients that may help boost your metabolism and help you burn stubborn fat. However, it must be paired with a healthy calorie-restricted diet and exercise for the best weight loss results.

Is Instant Knockout legit?

Instant Knockout is a good-quality supplement with scientifically proven ingredients for appetite suppression and fat burn. It may also help boost energy levels.

+ 23 sources

Health Canal avoids using tertiary references. We have strict sourcing guidelines and rely on peer-reviewed studies, academic researches from medical associations and institutions. To ensure the accuracy of articles in Health Canal, you can read more about the editorial process here

  1. de la Puente Yagüe, M., Collado Yurrita, L., Ciudad Cabañas, M.J. and Cuadrado Cenzual, M.A. (2020). Role of Vitamin D in Athletes and Their Performance: Current Concepts and New Trends. Nutrients, [online] 12(2), p.579. doi:
  2. Cleveland Clinic. (2022). Vitamin D Deficiency: Causes, Symptoms & Treatment. [online] Available at:
  3. Zhang, Z., Zhang, Y., Tao, X., Wang, Y., Rao, B. and Shi, H. (2023). Effects of Glucomannan Supplementation on Type II Diabetes Mellitus in Humans: A Meta-Analysis. Nutrients, [online] 15(3), p.601. doi:
  4. Fernandes, A.C.S., Muxfeldt, L., Motta, N.G., Skonieski, C., Fagundes, K.R., Sandri, G., de Chaves, D.B., Suthovski, G., Gallina, A.L., Araujo, S.M. and Benvegnú, D.M. (2023). Gummies candy enriched with Konjac glucomannan reduces hunger intensity and waist circumference of overweight individuals. International Journal of Biological Macromolecules, [online] 226, pp.72–76. doi:
  5. Zheng, J., Zheng, S., Feng, Q., Zhang, Q. and Xiao, X. (2017). Dietary capsaicin and its anti-obesity potency: from mechanism to clinical implications. Bioscience Reports, [online] 37(3). doi:
  6. Y, D. (2017). Capsaicinoids Enhance Metabolic Rate in Normal Healthy Individuals using a Novel Metabolic Tracker Breezing Device-An Open Label Placebo Controlled Acute Study. Obesity: Open Access, 3(2). doi:
  7. Bagheri, R., Rashidlamir, A., Ashtary‐Larky, D., Wong, A., Alipour, M., Motevalli, M.S., Chebbi, A., Laher, I. and Zouhal, H. (2020). Does green tea extract enhance the anti‐inflammatory effects of exercise on fat loss? British Journal of Clinical Pharmacology, [online] 86(4), pp.753–762. doi:
  8. Zhang, S., Yang, X., E, L., Zhang, X., Chen, H. and Jiang, X. (2023). The Mediating Effect of Central Obesity on the Association between Dietary Quality, Dietary Inflammation Level and Low-Grade Inflammation-Related Serum Inflammatory Markers in Adults. International Journal of Environmental Research and Public Health, [online] 20(5), p.3781. doi:
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Lindsey Desoto

Medically reviewed by:

Kathy Shattler

Lindsey DeSoto is a Registered Dietitian Nutritionist based out of Coastal Mississippi. She earned her BSc in Nutrition Sciences from the University of Alabama. Lindsey has a passion for helping others live their healthiest life by translating the latest evidence-based research into easy-to-digest, approachable content.

Medically reviewed by:

Kathy Shattler

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