Biomedical Science

Big Data & Plant Compounds: The Science Behind The Best Fat Burners

We review the scientific literature on fat burning compounds and make it simple to understand. Walking you through how ingredients in popular weight loss aids work, or don't and which if any natural fat burning compounds can actually deliver on the promises they make.

The Best Fat Burner

Dr Ian Smith - M.D., PhD

Best Weight Loss Aids

The obesity crisis has become one of the biggest impending disasters facing western society and the looming concerns for healthcare professionals have resulted in huge amounts of research being dedicated to weight loss. Whether that be through healthy lifestyle initiatives at a macro scale, or weight loss aids or "fat burners" being developed on mass to assist individuals trying to lose weight.

Over the last decade large amounts of dietary data has been compiled from across the globe to find correlation between healthier populations to see if anything can be found and in some ways it has been sort of a holy grail for scientists and the health and fitness sector alike as both parties search for the best fat burners. Over the years there have been several successful clinical applications of fat burners, with notable side effects, and some efficacy with natural fat burners has also been established, with fortunately minimal side effects.

However, as a result of these advancements, low regulation and a relatively uneducated market at large there have been substantial issues with poor quality supplements severely outnumbering the few evidence based fat burning supplements at approximately 5 to 1 based on our meta analysis and 1 in 10 being not only ineffective, but directly unsafe[1]. It has also led to a propensity of companies to promote wildly unreasonable claims when marketing a fat burner to the general public and a gross misunderstanding of the clinical applications of said products. This has led to a mistrust of what could potentially be useful tools to assist clinicians and individuals with weight loss. 
We seek to address this issue by not only covering which ingredients actually have functional use, educating the public at large. As well as listing a selection of quality over the counter products which are safe and effective. However, it should be noted that even high quality fat burners are not a replacement for lifestyle changes such as diet and exercise, however several of these natural alternatives to chemical compounds have the potential be of substantial assistance for individuals struggling to lose weight.

Do Commercial Weight Loss Aids Work?

Perhaps this is too broad of a question when tacking fat burning supplements. Weight loss supplements can work, in fact glucomannan has been proven to be particularly effective at suppressing appetite. But, the "fat burning" side of things is where research tends to get shoddy. If you're looking for a supplement to assist in a weight loss program then there are plenty available that should be beneficial. However, if we're talking about a fat burning supplement that can raise base metabolic rate in a substantial manner, then there is nothing that is commercially available, aside from stimulants like caffeine (and nicotine) which are not allowed to be promoted and or sold for this purpose in most western countries. There are some compounds which seem to show mild efficacy, however, they will not function by themselves and will only support as a weight loss aid, which most of the best fat burner supplements make clear in their marketing.

How Can Fat Burner Supplements Help Weight Loss In Adult Populations?

There are several elements to what is deemed a "fat burning supplement" the problem here largely comes from the naming convention. Most fat burners do not really help "burn fat", they mostly function as appetite suppressants, although some contain large amounts of caffeine, which will work, as mentioned before, they aren't allowed to market that element of the process. In general most of the best fat burning supplements work in a combination of the following ways. 

Appetite Suppression

This is relatively simple to understand if something helps reduce calorie intake then weight loss is generally going to follow as a consequence. There are generally speaking 3 ways in which this can take effect, the first being a filling effect from an ingredient like glucomannan (which swells to 50X the size of it's powdered form when in the stomach [2], 2g approximating the size of a bagel). The second is generally the way stimulants work, which effects neurochemical triggers. And the third usually is in relation to dopamine or cortisol regulation, this is where things get a little bit more complicated and are often marked more as craving reduction ingredients over directly appetite suppressants [3], although scientifically they overlap somewhat. 

Craving Reduction

Fat burning supplements generally work most effectively when they help prevent breaking of a calorie controlled diet. Craving reduction thus becomes quite a powerful option. Ingredients like 5htp [4] and even mood regulators can have a notable effect on this due to cortisol’s effect on appetite [5]. Although it should also be noted that the placebo effect itself can be incredibly useful for this sort of weight loss assistance.  

Increased Thermogenesis

Like craving suppression increase in thermogenesis is where many of the fat burners on the market start to get a little pseudoscientific, marketing claims run rampant, and the things that actually do work are often restricted from being promoted due to marketing regulations, particularly in Europe [6]. Increasing thermogenesis means that your body will burn more calories whilst resting or whilst undertaking anaerobic activities depending on what the ingredients proport to do. A lot of supplements focusing on this base their claims on animal or other low quality studies. 

Increased NEAT (Non-Exercise Activity Thermogenesis)

Generally speaking people's NEAT drops substantially after a large amount of cardio or whilst on a calorie restricted diet. This is the body's natural reaction to wanting to preserve energy when in a caloric deficit. As such stimulants and energy boosting ingredients can help mitigate these effects, the most well known of these being caffeine [7]. Because this also increases muscle usage it helps prevent muscle mass wastage during diets. 

Fat Binding Dietary Supplements

This is probably the least effective form of dietary supplements. Ingredients that pertain to have these effects should not make up a large portion of any effective fat burning supplement. 

The Science Behind The Best Fat Burner Ingredients

There are relatively few properly studied ingredients that are available over the counter that have been clinically proven to aid with weight loss. And even few with robust studies and a concrete scientific understanding behind them. The most promising as it stands are: 

– Glucomannan is a dietary fibre that comes from the Konjac Root. It has found recent use in the creation of incredibly low calorie noodle and rice replacers, due to it being undigestible by humans. The ingredient works via swelling inside the stomach creating a feeling of fullness. It is theorised that the optimal time to take a glucomannan supplement is around 30 minutes before food preparation as this will lead to improved psychological food prep (producing a smaller portion) as well as feeling more satiated during consumption. In studies it has been shown that even high volumes of glucomannan is ineffective in morbidly obese patients without further dietary or physical exercise changes [8], but as little as 1000mg daily[9] has been enough to display notable statistical improvements in outcomes over placebo groups in overweight to obese individual. The poor outcomes in morbidly obese patients can be relatively easily explained through a larger stomach capacity, thus glucomannan displaying reduced efficacy. Also in both of these studies patients were asked not to change their dietary or exercise habits. As such, it is quite plain to see that due to the way glucomannan works, this was not likely to be all too effective as it doesn’t have any effect on thermogenesis or energy levels. Glucomannan has been most effective as an assistant to maintaining a calorie deficit as it reduces hunger cravings and if taken at the correct times can reduce binge eating behaviours [10]. However, dosages should be around or over 2000mg to be effective for normal individuals, weights between 130-200lb and within healthy to moderately overweight BMI. Any less than this and efficacy will be reduced [11]. However, as people typically make better food choices when they do not feel hungry [12] glucomannan’s function as a weight loss aid seems quite simple. As a secondary benefit, it has also been shown to lower high cholesterol levels when consumed in large enough volumes [13] and is licenced for use as such. 

– 5HTP is largely utilised as a craving suppressant in fat burner products. The compound was previously only available via prescription until 1995, with the FDA moving to approve it as an over the counter supplement due to it’s low risk and high efficacy [14]. One of the better studied compounds, it is particularly effective at dealing with hedonic appetite. The most interesting study for our understanding of 5HTP’s role in cravings and food selection was conducted in 2016 [15], with participants undertaking MRI scans after taking 5HTP supplements against a control group. The participants who had taken the supplements showed less response to being shown high calorie, carbohydrate rich foods and an increased interest in high protein nutritionally rich foods. This was particularly prevalent in female participants. This is likely due to the evolutionary nature of male vs female tastes in food, which is hypothesised to be as a result of illness prevention during fertile periods, with sweet foods generally being safer for consumption. 5HTP has been shown to be most effective in treating overweight females [16] and has promoted increased weight loss outcomes.  

– Caffeine is particularly effective for three reasons, it’s increase in NEAT [17], it’s appetite reduction [18] and the fact that is one of the few ingredients that actually increases thermogenesis [19]. 

Cayenne Pepper Extract
- Often referred to as Capsimax is an ingredient that did unfortunately have it’s reputation tarnished by a lot of wild claims by the fat burner industry a decade ago. Whilst it does have some efficacy in clinical trials in average patients [20] it was not nearly as impressive as the unreasonable claims that were made of the ingredient. However, dosed at around 100mg it has been shown to have statistically significant results in aiding weight loss overall in overweight patients [21] and in direct fat loss specifically when applied to healthy participants who were participating in training [22]. Overall making it a good inclusion and one of few fat burning supplements to actually deserve the claim. 

Green Tea Extract
– Green Tea extract was noted to be effective in obese trial participants [23]. However, it’s main efficacy, in theory, is that it improves the bodies ability to oxidise fat cells during aerobic activity [24]. Making it’s primary function beneficial only for use that coincides with at least moderate physical activity. With this in mind it should help the body metabolise fat rather than muscle when in a caloric deficit, leading to the retention of lean muscle mass. 

L -Theanine
– The amino acid L Theanine functions in two ways; one being that it reduces the stress hormone cortisol [25], thus assists with craving reduction, and secondly it assists with the browning of white adipose tissue, in other words helps the body convert fat stores during anaerobic activity [26].  

It should be noted that there are other commercially available products, that whilst effective have noted side effects and are not legal for promotion in this context. 

The Best Fat Burner Supplements Commercially Available In 2023

There are a wide range of fat burning supplements on the market right now and we've realistically narrowed it down to perhaps one dozen that would actually be effective. And significantly less if we're looking at stimulant free fat burners. 

We've cut that list to the 3 best fat burners for now based on the reputations of the manufacturer as well as the ingredients list. Although we intend to add some more niche products to this list in the future.

This list whilst not exhaustive, it should cover a quality fat burning supplement for most use cases.

Instant Knockout Cut - Best Fat Burner With Caffeine

Instant Knockout Cut was originally designed to help MMA fighters cut weight for weigh ins without loosing lean muscle mass. It's been a staple of the fitness industry for more than a decade and has gone through several formula changes over that time as the science has moved on. 

The main focus ingredients are caffeine and glucomannan. With the former being proven to raise BMR, reduce appetite and keep energy levels high during a calorie deficit and the latter being designed to reduce hunger overall. It also includes several other performance and energy boosting ingredients including a large dose of vitamin D which has been proven repeatedly to increase athletic performance (especially when on a reduced calorie intake) and help boost willpower and mood whilst dieting. 


Ingredients In Instant Knockout Fat Burning Supplements

Instant Knockout contains as we've mentioned the two most beneficial ingredients for any fat burner, caffeine and glucomannan, but beyond that is has some other particularly beneficial inclusions.  

Vitamin D - As mentioned Vitamin D is particularly beneficial for increasing cardio performance. 

Vitamin B Complex - Included in a lot of fat burning supplements, especially those that are designed for people already undergoing a training regimen, due to it's benefits to improved anaerobic performance. 

Green Tea Extract – Whilst not one of our favorite ingredients, it does have some benefits to weight loss aids. And as it’s the least prominent ingredient in instant knockout that’s a completely valid addition. 

L-Theanine – Typically only found in premium fat burner pills L Theanine is a particularly efficient at suppressing appetite, but only at dosages of 100mg or above, most fat burners don’t actually have it in a high enough volume to be effective, although instant knockout does supply the recommended dosage. 

Cayenne Pepper Extract – Cayenne powder, or capsimax is one of the few ingredients that was hugely popular in the late 90s to have actually stood the test of time, whilst it is predominantly a thermogenic ingredient, it is perhaps the only one that isn’t a stimulant that has reasonable scientific backing. The dosage of 100mg in Instant Knockout is ideal, and larger amounts show diminishing returns although a lot of competitor products do rely on this too heavily. 

Instant Knockout Rating 5/5

High in glucomannan and caffeine, Instant Knockout focuses on the areas of a fat burner that actually work. It's priced competitively and the company that produces it has a stellar reputation. 

It's price point does mean that it is best bought in bulk, as the product is designed to be taken over a 3 month period and offers a money back guarantee this is less of an issue. We highly recommend Instant Knockout.


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