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Instant Knockout Cut Review: Evaluating the Benefits and Risks of This Supplement

By Kelsey Costa, MS, RDN

Last Updated on February 29, 2024

Medically Reviewed by Natalie Olsen, MS, RDN

Dietitian Rating:


About This Rating
The average rating of this product is calculated based on the evaluation of the following factors:
  • Support for Claims:3.5
  • Ingredient Safety:3.5
  • Customer Service:3.0
  • Value for the Price:3.8

In this review of the natural fat burner Instant Knockout, we evaluate the evidence on its ingredients and pinpoint critical highlights on purported benefits, potential risks, pricing, and efficacy for weight loss and provide practical advice from a dietitian.

Written by
Kelsey Costa, MS, RDN
Registered Dietitian
Kelsey Costa is a registered dietitian, business owner, writer, and editor with years of experience in health and wellness. She earned a Master of Science in Health and Wellness Management from Merrimack College and completed her dietetic internship with Wellness Workdays, a nationally recognized corporate wellness company.
Medically Reviewed by
Natalie Olsen, MS, RDN, LD, ACSM-EP
Registered Dietitian, Certified Exercise Physiologist
Natalie is a registered dietitian, functional medicine practitioner and certified exercise physiologist with over 15 years experience in the health and wellness industry and holds a Master's degree in Human Nutrition and Functional Medicine through a collaborative program provided by the University of Western States and the Institute of Functional Medicine.
Instant Knockout Cut Review: Evaluating the Benefits and Risks of This Supplement

Key Highlights

  • Instant Knockout contains 9 natural ingredients that may help with weight loss by boosting metabolism, suppressing appetite, and promoting fat-burning.
  • Caffeine and vitamins B6 and D3 provide energy, mood, and workout benefits, but effects will vary from person to person.
  • Ingredients such as green tea extract, glucomannan fiber, and black pepper extract have some clinical backing for weight loss, but optimal doses are uncertain.
  • Those sensitive to stimulants or with medical conditions should be cautious and consult a doctor first due to potential side effects.
  • At 4 capsules per day, one bottle provides a 30-day supply. Returns are only allowed on unopened items within 30 days of US purchases.

Instant Knockout Overview

Manufactured by Roar Ambition, Instant Knockout Cut is designed to be a safe and natural fat-burning supplement meant to promote weight loss through metabolism support. This product may also help to reduce hunger cravings and fuel energy levels for workouts.

Instant Knockout Cut was developed for professional athletes in combat sports and is now backed by several boxing and MMA champions.

Even if you’re not a professional athlete, this supplement could help you reach your goals.

Though it may work for people of all activity levels, the company discloses that the best results will be seen in active adults who maintain a healthy diet and regular exercise.


  • Contains clinically studied ingredients that support weight loss
  • Has a transparent label, showing ingredient concentrations
  • Contains ingredients that can support your exercise and workout routines
  • This product is vegan, and gluten-free


  • Restricted return policy with no trial period to test out the product
  • Stimulant ingredients pose a safety risk for some people

Evaluating the Claimed Benefits

Instant Knockout Cut is marketed as a two-in-one “fat burner”, claiming to suppress your appetite while offering metabolism-boosting benefits.

The brand also claims that this supplement supports energy, mood, and focus to enhance your exercise performance and help you reach your goals.

Below, we’ll explain each claim and whether scientific research supports the ingredients’ role in the purported claims.

Reduces Body Fat

Some evidence suggests that among the active ingredients in Instant Knockout Cut, green tea extract and black pepper extract (piperine) may help reduce body fat, but through different mechanisms. Green tea extract may help by promoting fat oxidation, while black pepper extract may help prevent the growth of new fat cells.

Green tea contains antioxidants known as catechins, which are believed to promote fat oxidation. (1, 2)

Note: Fat oxidation is important to the body's overall fat-burning process. When the body breaks down fats through oxidation, it results in the release of energy. The body can use this energy for various functions. (3)

Including green tea extract in your diet may help you lose weight by increasing the amount of fat that your body burns, though the evidence is limited. (1, 2)

Research on the effective dose of green tea extract on weight loss varies. Older studies have shown doses of 270 milligrams (mg) to 1200 milligrams (mg) per day to be effective (4). A more recent study showed that 780 mg of green tea catechins may be effective for improving energy metabolism and fat loss. However, further research is needed to confirm these findings. (5)

Instant Knockout Cut contains 500 mg of green tea extract per daily serving (four capsules), so it may provide an effective dose of green tea extract for weight loss.

Piperine is a compound found in black pepper extract. Although limited, human research has shown that piperine blocks an enzyme that creates new fat cells. However, the way it works is not yet fully understood. (6)

There is no clinically agreed-upon effective dose of piperine for weight loss, but typical doses of piperine range from 5 mg to 20 mg per day. (7, 8, 9)

Instant Knockout Cut falls within this range, providing 10 mg black pepper extract (piperine) per daily serving (four capsules).

Suppresses Appetite

The glucomannan fiber present in Instant Knockout Cut has been shown to increase feelings of fullness. Therefore, it may help to reduce hunger and cravings. However, caffeine anhydrous has mixed evidence to support appetite suppression.

Glucomannan is a water-soluble dietary fiber that comes from the Konjac plant.

When consumed with water, it swells up to form a thick gel inside the stomach. This gel delays gastric emptying and, therefore, suppresses appetite.

Ingesting glucomannan fiber may make you feel full for longer after eating, which may also help to reduce your cravings and overall calorie intake.

Studies have shown that glucomannan can help people lose weight and reduce body fat in the short term, but long-term studies have been inconclusive. (10)

The clinically studied dose of glucomannan is 2–4 grams (g) per day. (11, 7)

Instant Knockout Cut only contains 1.8 grams (1800 mg) of glucomannan per daily serving (four capsules).

Caffeine anhydrous is a dehydrated caffeine powder extracted from coffee plants' seeds and leaves.

There is mixed evidence on the effect of caffeine on appetite, though recent research suggests that caffeine may have a minimal or no effect on controlling appetite. (12, 13)

Boosts Metabolism

Instant Knockout Cut may offer both a thermogenic and metabolic boost with caffeine anhydrous, cayenne pepper powder, and Vitamin B6 and B12

Though separately defined, a thermogenic boost (thermogenesis) is related to metabolism because it helps produce heat, and the body burns calories faster when it's warm.

This may be beneficial for weight loss, as well as general health and wellness.

Studies have shown that caffeine consumption may help to reduce body weight, body fat, and body mass index (BMI). (14) This may be due to its metabolism-boosting effects. Doses vary, but some studies have shown metabolic improvements with doses up to 300 mg. (15)

However, the United States Food and Drug Administration (FDA) recommends limiting caffeine intake to 400 mg per day for adults.

Instant Knockout Cut contains 300 mg of caffeine anhydrous per daily serving (four capsules), so this may be a sufficient dose of caffeine to boost metabolism for most people.

Cayenne pepper seeds contain antioxidants, vitamins, and capsaicin.

Capsaicin may assist with weight loss by helping to regulate metabolism, increase diet-induced thermogenesis, and decrease calorie intake. (16)

Clinical doses of capsaicin typically range from 2–6 mg per day. (17, 18)

Cayenne pepper contains about 2.5 mg of capsaicin per gram, so you would need to take at least 800 mg of cayenne pepper powder per day to fall within this range. (19)

Instant Knockout Cut only provides 100 mg of cayenne pepper powder per daily serving (four capsules), so it may not provide a sufficient dose of capsaicin to boost metabolism for most people.

Vitamins B6 and B12 are water-soluble vitamins that help to regulate metabolism, forming and breaking down nutrients in the body.

Both vitamins are associated with lower BMI and improved body composition. (20, 21)

If you are deficient in either of these vitamins, supplementation could help your metabolism return to an average level of function.

The recommended daily amount of vitamin B6 is 1.7 milligrams (mg), and 2.4 micrograms (mcg) for vitamin B12. (22, 23)

Instant Knockout Cut contains 5 mg of vitamin B6 and 10 mcg of vitamin B12, which is over 100% of the daily value for both vitamins.

Supports Energy, Mood, and Focus

With caffeine anhydrous, L-Theanine, vitamin B6, and vitamin D present in Instant Knockout Cut, this supplement may help support energy, positive mood, and focus. This, in turn, can enhance your exercise performance and motivation toward goals.

When taken in average doses of 300 mg per day (equal to about 2–3 cups of coffee), caffeine has been shown to block the effects of a neurotransmitter called adenosine. This raises the brain's dopamine, which can improve mood, reduce fatigue, and increase alertness. (24)

Moderate doses of caffeine of at least 5 milligrams per kilogram of body weight may also decrease pain during workouts and reduce your perceived level of exertion, making workouts feel easier. This may result in improved exercise performance. (25)

However, this benefit appears only to be seen when caffeine is taken in a single dose, about 60 minutes before a workout.

Instant Knockout Cut contains 300 mg of caffeine anhydrous per daily serving (four capsules), so this may be a sufficient dose of caffeine to provide such benefits.

L-theanine promotes relaxation. Some people take L-theanine with caffeine with the goal of “canceling out” some of caffeine’s negative side effects. However, one older study showed it did not appear to significantly affect alertness, anxiety, or jitteriness associated with caffeine consumption. (26)

L-theanine is typically taken in a 100–200 mg dosage. Instant Knockout contains 100 mg of L-theanine per daily serving (four capsules).

Vitamin B6 is necessary for the conversion of tryptophan to serotonin. If someone doesn't have enough vitamin B6, they might not be able to produce enough serotonin, which could lead to a mood disorder, such as depression. (27)

However, some older studies have not shown supplementation with vitamin B6 to prevent or treat depression. (28, 29)

With 5 mg of vitamin B6 (294% of the Daily Value) per daily serving, taking Instant Knockout Cut could help to prevent vitamin B6 deficiency. However, it is important not to take too much B6, so be aware of the total amount of vitamin B6 being taken daily in other supplements and energy drinks. [source]

Instant Knockout makes very general claims about vitamin D supplementation and exercise performance.

While the company does not specifically claim that vitamin D can support mood, vitamin D fits under this benefit as it has been shown to reduce negative emotions. (30)

The dose of vitamin D for this purpose appears to be less than or equal to 4,000 IU/day for at least eight weeks. The effects have been more pronounced in those who have a major depressive disorder or suffer from vitamin D deficiency. (30)

Instant Knockout Cut contains 45 mcg (1800 IU) of vitamin D3 (225% of the Daily Value) per daily serving (four capsules).

Vitamin D3 has been shown to raise serum levels more effectively than vitamin D2, so taking Instant Knockout Cut could help prevent vitamin D deficiency. (31)

Expand Full Ingredient List

Instant Knockout Cut contains nine main ingredients, including:

  • Vitamin D3: 45 mcg (1800 IU)
  • Vitamin B6: 5 mg
  • Vitamin B12: 10 mcg
  • Glucomannan (Amorphophallus Konjac): 1800 mg
  • Green Tea Extract (Camellia Sinensis): 500 mg
  • Caffeine Anhydrous: 300 mg
  • L-Theanine: 100 mg
  • Cayenne Powder (Capsicum Annuum): 100 mg
  • Black Pepper Extract (Piper Nigrum): 10 mg

How to Take Instant Knockout

The recommended and maximum dosage for Instant Knockout Cut is four capsules per day, spread throughout the day.

It is recommended to take one capsule first thing in the morning, one before lunchtime, one in the afternoon, and the last before the evening meal.

If you take your last dose of Instant Knockout Cut too late at night, it could interfere with getting adequate sleep — a side effect of most stimulants.

Safety and Side Effects

This supplement is recommended only for adults ages 18 and over. Do not take this supplement if you are pregnant or nursing. Do not take this supplement if you are sensitive to stimulants or have a history of heart conditions or high blood pressure.

Because Instant Knockout contains green tea extract and caffeine anhydrous, those with sensitivities to stimulants should avoid this product.

Caffeine anhydrous is a highly concentrated form of stimulant. For this reason, it can be especially dangerous if you have a history of heart conditions. You may react differently to it than to natural forms of caffeine.

It is unclear how much caffeine is provided by the green tea extract, as caffeine content in green tea extract varies by brand. Because this supplement appears to contain multiple forms of caffeine, it is important to not exceed to maximum daily dosage.

Excess caffeine can lead to restlessness, nausea, agitation, rapid heart rate, and elevated blood pressure.

That is why the FDA recommends limiting caffeine intake to no more than 400 mg daily (an equivalent of about three to four cups of coffee). (32)

Additionally, do not take this supplement with other products that contain stimulants or caffeine, such as coffee or tea, as this may cause you to have an unsafe intake of caffeine.

Rapid intake of caffeine of over 1,000 mg or higher has been associated with seizures and even death. (33)

Beyond the potential side effects from stimulants, there are also potential side effects from the glucomannan fiber that is included in this supplement.

Glucomannan has been associated with gastrointestinal side effects like increased belching, bloating, stomach fullness, and diarrhea. However, most clinically studied doses of glucomannan are higher than the dose present in Instant Knockout Cut. (34)

In the amounts present in a daily serving of Instant Knockout Cut, negative side effects from vitamin D3, vitamin B6, vitamin B12, L-theanine, cayenne powder, and black pepper extract are unlikely for most people.

Be sure to consult your doctor before using this supplement, especially if you have any known medical conditions or are currently taking medications.

Instant Knockout Cost

Instant Knockout is available to purchase from the company’s official website through the following pricing options:

  • 1-Month Supply: $65 + $8.95 for shipping
  • 2-Month Supply: $130 + free shipping in the USA and UK
  • 4-Month Supply/Ultimate Shredding Stack: $195 + free shipping worldwide

One bottle of the product contains 120 capsules. At four capsules a day, it provides a one-month (30-day) supply.

Returns are only available for unopened and unused products. Returns must be made within 30 days of receipt in the US and within 14 days of receipt in the UK and elsewhere.

Without the chance for a trial period, this strict return policy means you must be ready to part with the money if the product does not work for you.

Buy Instant Knockout Cut

How Instant Knockout Compares to Alternatives

The fat burner supplement market offers a wide variety of products with different ingredients and ways in which they promise fat loss and claim similar benefits as instant Knockout.

However, some may lack evidence to support their claims and contain potentially dangerous ingredients.

Consumers should be cautious when choosing a fat burner supplement and should always consult a doctor before starting any new weight-loss regime.

Here’s how Instant Knockout compares to two other popular brands:


Leanbean is an all-natural fat burner supplement that promises to help women lose weight quickly and easily.

Similar to Instant Knockout Cut, Leanbean claims to help boost metabolism, reduce appetite, and increase energy levels.

However, LeanBean is a low-stimulant supplement, meaning it does not contain high amounts of caffeine like many fat burners.

The main ingredients in Leanbean include glucomannan, choline, vitamin b6, vitamin b12, chromium picolinate, chloride, zinc, green coffee, turmeric, garcinia cambogia, acai berry, and piperine.

Leanbean contains a higher dose of glucomannan fiber (3000 mg) compared to Instant Knockout Cut. However, Leanbean requires a serving of six capsules per day instead of four, like Instant Knockout.

A one-month supply (180 capsules) of Leanbean costs $59.99, which is a little cheaper than Instant Knockout.

Leanbean may be a better choice than Instant Knockout if you want a low-stimulant supplement.


Another all-natural fat burner is Skald Oxydynamic Fat Scorcher (Skald). Like Instant Knockout, Skald claims to promote fat loss, appetite control, increased energy, and elevated mood.

The Skald product’s safety is emphasized, yet the company does not reveal the amount of each ingredient included in its product.

The proprietary (patented) blend of ingredients includes caffeine anhydrous (110 mg), N-Acetyl-Tyrosine, green tea leaf extract, juniper (Juniperus communis) berry extract, white willow bark extract, Verbascum thapsus leaf powder, elecampane root powder, and Bioperine black pepper fruit extract.

Skald only requires a serving of two capsules per day, instead of four like Instant Knockout

A one-month supply (60 capsules) of Skald can be purchased for $49.00, which is also significantly lower than Instant Knockout.

Overview Table

Instant Knockout Leanbean Skald
Key Claimed Benefits Appetite control, Boosts metabolism, Helps you cut, Thermogenic boost, Energy Energy & metabolism support, Reduce hunger, Improve blood sugar Energy and respiratory support, Appetite control, Fat loss, Improved mood
Suggested Daily Amount 4 Capsules 6 Pills Up to 3 Pills
Key Ingredients

Glucomannan, Cayenne Pepper, Green Tea Extract, Caffeine, L-Theanine, Vitamin D3

Glucomannan, Choline, Vitamin B6 & B12, Chromium picolinate, Chloride, Zinc, Green coffee, Turmeric, Garcinia Cambogia, Acai berry, Piperine Proprietary blend that contains Juniper Berry Extract, White Willow Bark, Elecampane, Catechin, Caffeine Anhydrous, N-Acetyl L-Tyrosine, Mullein, BioPerine
Third-Party Tested No No No
Vegan Yes Yes No
Regular Price $65 per bottle (1-month supply) $59.99 per bottle (30-day supply) $49 per bottle (60-day supply)
Lowest Price per Bottle $48.75 per bottle when you buy 4 $47.48 per bottle when you buy 4 $35.28 per bottle when you buy 6 bottles and subscribe
Shipping Cost Free Free shipping in UK for 2 bottles; Free worldwide shipping for the bundle, otherwise $7.95 $5 or free when you order 3 or more bottles
Return Policy 30 days for USA/Canada & 14 days for UK and everywhere else only on unopened products 90 days for the bundles (4 bottles), otherwise it’s 7 days for unopened products plus a processing fee 60-day money-back guarantee, including for used products

The Bottom Line

Instant Knockout Cut appears to be a promising fat-burning supplement, including all-natural ingredients that are relevant to weight loss and metabolism.

While the most effective ingredient appears to be caffeine anhydrous, most of this product's other ingredients are backed by solid research.

This product may aid in weight loss by reducing body fat, suppressing appetite, and boosting metabolism.

It may also support your energy, mood, and focus—helping you improve your athletic performance and reach your goals.

If you are an active adult looking to lose weight faster, this could be a safe fat-burning supplement to use in combination with a healthy diet and lifestyle.

Still, it is best to check with your doctor before trying this supplement, especially if you may be sensitive to stimulants like caffeine or have certain medical conditions, such as heart issues.

A Word from a Dietitian

Weight loss supplements are only intended to support, not replace, a healthy diet and active lifestyle.

Changing your diet and increasing your physical activity is crucial if your goals are to improve your exercise performance, body composition, and overall health.

Making the shift toward a plant-based diet may be helpful. Focus on fruits, vegetables, lean proteins, whole grains, and healthy fats. This way of eating can help support your metabolism by providing the nutrients your body needs to function at its best.

If you are trying to lose weight, including foods that promote fat oxidation in your diet may be helpful. Foods that are rich in antioxidants, such as fruits and vegetables, are good choices for promoting fat oxidation.

Try incorporating regular strength-building and cardiovascular activities for a minimum of 150–300 minutes per week to help you reach your goals.

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At WellnessVerge, we only use reputable sources, including peer-reviewed medical journals and well-respected academic institutions.

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