How to pick the best fat burner

Real talk. All fat burners are not created equal.

There are some targets we all expect our fat burning supplements to deliver on:

  • Firing up our basal metabolic rate
  • Suppressing appetite
  • Boosting energy

We looked at the weight loss supplements making waves around the internet and narrowed the field down to the highest performing three. We chose our 3 best fat burners based on ingredient quality, transparency, and performance.

best fat burner

#3. Phentaslim—OptimumNutra

Medical History

Opening up the floor for our 3 Best Fat Burners, this high performer has a proven track record with 100,000 happy customers in 8 years. What the company lacks in aesthetics (the website looks a little sketchy) it recovers in performance, customer service, and ingredient transparency.


Setting aside the three major goals—what we expect from a supplement that makes our 3 Best Fat Burners list—Phentaslim offers some interesting side benefits. L-Theanine combines with caffeine to boost concentration levels and reduce stress and anxiety. Both score major points in any supplement. OptimumNutra rounded the fat-burning genius out with vitamins, minerals, and antioxidants to boost immunity. Of our 3 best fat burners, Phentaslim is the only one to take that route.

Side Effects

Phentaslim recommends that people avoid this supplement if they are pregnant, breastfeeding, have a BMI of less than 18.5, or are under 18. Our vegan readers may want to scroll further down the list, too. Phentaslim uses a gelatin-coating for its capsules, which makes it unsuitable for you.

It’s important to keep in mind that any product which contains caffeine can cause the following side effects:

  • Insomnia
  • High blood pressure
  • Digestive upsets
  • Increased heart rate
  • Increased levels of anxiety


1 capsule, 3 times a day. Because of the caffeine component, you should aim to take the last capsule no less than 4 hours before sleep.


Phentaslim doesn’t perform to the same level as our next contender. OptimumNutra have put their focus on health, nutrition, and long-term support for successful weight loss. They also offer free shipping and 24/7 online support. That’s a definite win in these books.

#2. Instant Knockout—Roar Ambition

Medical History

Instant Knockout is manufactured by U.K. company Roar Ambition (see what they did there?).

Pro athletes originally used it to drop weight before major events—think MMA fighters and boxers. Arguably one of MMA’s biggest names, Diego Sanchez, lends his name to the product’s marketing. If you want to position yourself as one of the 3 best fat burners available, a pro MMA coach endorsement doesn’t hurt either.


This capsule formulation focuses on the three key areas of any fat burning supplement and excels in all of them. It earns its place on our list of the 3 best fat burners because it executes every step with absolute precision.

To boost your natural metabolic rate, it packs a punch with cayenne pepper seeds, green tea extract, and vitamin B6.

Glucomannan lends dietary fiber to the mix, to reduce cravings and keep you feeling full. Chromium stabilizes blood-sugar levels, to help you avoid over-eating and mood dips.

Fat burning staple, caffeine, helps even pro athletes dial up the energy and focus for intense workouts.

Side Effects

The major side effect to this supplement stems from the 300mg caffeine intake for 4 capsules (the daily recommended dosage).

Unfortunately, the gelatin capsule casing means this is not a vegan-friendly supplement either.


4 capsules total—1 first thing in the morning, and once every 3 hours thereafter. Many Instant Knockout fans recommend taking the tablets on an empty stomach, and as always—assess your tolerance level.


This supplement is no joke. Its high potency formula, clinically effective ingredients, and strong customer reviews land it decisively on our 3 Best Fat Burners list.

#1. PhenQ—BAUER

Medical History

PhenQ was launched by BAUER in 2015. Our #1 choice of the 3 best fat burners has a respected name in the supplements industry, with over 10 years of proven results. They manufacture at FDA approved facilities and use high quality, all-natural ingredients.


This one checks all the boxes.

Boosting your basal metabolic and thermogenic rates?

Yes. The addition of Capsimax—BAUER’s proprietary blend of piperine, caffeine, niacin, and capsicum—have strong thermogenic capabilities to ramp up your body heat and burn more fat.

Providing natural appetite suppression?

Absolutely. Chromium Picolinate—found in meat and whole grains—helps stabilize crazy blood-sugar fluctuations, and reduce carb and sugar cravings. Nopal—which comes from a cactus—brings the fiber content so you feel full for longer.

Giving you a clean, quality energy boost?

Definitely. One of the reasons PhenQ makes the cut in our list of the 3 Best Fat Burners is its balance of natural stimulants. We’ve got caffeine to keep us alert and reduce mind and body fatigue. We’ve also got L-Carnitine. This amino acid converts fat stores to energy, making that converted energy available to the body. Blending L-Carnitine and Chromium Picolinate gives us some serious mood-boosting goodness. No easy feat when you’re dieting.

Side Effects

According to BAUER, there are no reported side effects of PhenQ. Be aware, though, that the supplement contains caffeine, so the usual side effects apply.


One tablet with breakfast, and one with lunch.


You’d be hard-pressed to find a better all-natural fat blaster to round out any 3 Best Fat Burners list. This supplement has the backing of a proven company, with strong results, and hits every target for weight loss in both men and women.

And the winner is . . .

So you’ve met the 3 best fat burners on the market right now. Every supplement that made it onto our 3 Best Fat Burners list is a worthy contender for the champion title. YMMV (your mileage may vary) definitely applies to fat burning supplements.

Exercising restraint in its use of caffeine is where PhenQ gains the edge to take out the #1 spot. It is also the only one of our 3 best fat burners which is vegan-friendly.

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