Do Ab Belts Work? Here’s Exactly What Ab Stimulators Can & Can’t Do

Do ab belts work?

Belts that use electronic muscle stimulation to supposedly zap your abs into shape have been on late-night infomercials for decades, but I’ve always wondered if they were any good or not.

So I researched the answer to this question, and in this article I present all of the facts & fiction about ab stimulators that I could track down.


Other ab belt topics covered

I also answer several other related questions about these fixtures of “As Seen On TV” product best-seller lists:

  • What is it that ab belts actually do?
  • Do ab stimulators shrink belly fat?
  • Do they cause weight loss?
  • Can they give me six-pack abs like they promise?


Article summary: what ab belts can & can’t do

An ab stimulator can strengthen & tone ab muscles for some people, if used frequently and with sufficient intensity. 

An ab stimulator belt has been shown to decrease waist size in only one research study, and the results don’t represent the general public.

An electric ab belt has not been proven to reduce belly fat or cause weight loss.

The right diet plus exercise remains the most effective way to accomplish those goals.


What’s next

Up ahead, I’ll go into more detail on what ab belts can do for you, and what clinical research testing of ab stimulators has found.

We’ll also look at what buyers of popular ab belts have to say about how well they work.

And I’ll discuss how EMS (electronic muscle stimulation) can be effectively used for the target toning & strengthening of specific muscles, but that the ability to target specific areas for fat loss remains a wishful myth.



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Science resources included

As is my custom here on heydayDo, I will provide links to all of the relevant sports science and medical resources, clinical studies, & nutritional data used in this article.




Do ab belts work? Let’s review the abs stimulator research

Let’s look at what scientific testing has actually determined about EMS devices, starting off specifically with ab belts.

Early studies on the ab stimulator that I found from 2002 were conducted by Bio-Medical Research in Ireland.

Unfortunately these studies are listed as unpublished, so I couldn’t read them.


I know about them because they are referred to in this ab stimulator study from 2005, conducted by the University of Wisconsin-La Crosse.

The UW-La Crosse authors wrote that Bio-Medical Research’s 2002 ab belt study

“…found that use of this system improved isometric strength, isometric and dynamic endurance, and a number of self-perceived outcome measures.”


Those “self-perceived outcome measures” are later described as the participants’ saying that their abs felt toned, and that they also had more positive feelings about their body shape & appearance.

It was Slendertone & Flex Belt’s own research

It’s important to note that Bio-Medical Research (BMR) is the company that owns & markets both the Slendertone and The Flex Belt brands of ab stimulators.

An early version of today’s Slendertone was used in their 2002 ab belt EMS study.


2005 UW-La Crosse ab belt study

The authors of the 2005 ab stimulator study I mentioned earlier set out to independently verify those results from BMR.

They noted the “inherent bias characteristic of in-house studies”, given that Slendertone is one of BMR’s products.

Their study methods replicated those of Bio-Medical Research, using a Slendertone ab stimulator for 8 weeks and testing for abdominal strength.


Results? Smaller waistlines & stronger abs

The Univ. of Wisconsin researchers duplicated the same results as the BMR study, and determined additional positive outcomes as well, concluding that

“This study found that the use of the Slendertone FLEX™ belt 

  • significantly increased abdominal strength and endurance, 
  • decreased waist girth, 
  • and improved self-perceived abdominal firmness and tone.” 

I reviewed the statistical data, and can report that after 8 weeks, the participants using the ab stimulator:

  • reduced their waist size by 3.6 cm (1.4”)
  • reduced their abdomen by 2.6 cm (0.78”)
  • increased ab muscle strength by 40%
  • increased ab exercise repetitions by 100%

On the “no change/didn’t work” side of the ab belt study, the results showed:

  • no loss of weight
  • no change in body mass index (BMI)
  • no reduction in the largest part of their belly


Bottom line: The ab muscles got stronger by a lot considering it was only an 8 week study, and the belly area shrunk some in a couple of places.


Belly fat & weight loss did not occur.


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2018 UW-La Crosse ab belt study

13 years later John Porcari, who led UW-La Crosse’s previous ab belt study in 2005, conducted another research trial using EMS in 2018.

He tested the newer Slendertone Systems Ab Belt for its effect on the same parameters as his 2005 study:

  • ab strength
  • ab endurance
  • ab girth
  • body shape perception
  • body satisfaction

One difference from his work in 2005 is that this 2018 study tested both high & low-intensity stimulation.

The conclusions were that high-intensity stimulation can significantly increase strength & endurance, more than low-intensity.

Once again, body weight, BMI (body mass index), and overall waist size did not change.



Ab belt studies vs. the real world

There are a couple of shortcomings to point out with regards to the positive results obtained in these ab stimulator studies from Bio-Medical Research and the UW-La Crosse sports science department.

These issues have to do with whether those studies’ results could be achieved by the majority of the general public, the people who’re watching the infomercials here in 2019, and reaching for their credit cards.


1. Bio-Medical Research = Slendertone

I believe BMR believes in their technology; they’ve been around for a long time and their EMS devices have a wide range of proven therapeutic applications.

And for some people, their ab stimulator belt has strengthened & toned abdominal muscles.

This has been proven.


And in 2002 when the FTC – our Federal Trade Commission – came down hard on a few ab belt manufacturers for making false advertising claims on late-night TV (like “six pack abs with no exercise”) , Slendertone was not one of those accused or punished.

Still, that 2002 study that they conducted is for a product of theirs that they aggressively market.

It’s hard to completely ignore the elephant in the room that is conflict of interest.


2. Small sample sizes in all 3 studies

Both the BMR & the two UW-La Crosse studies had very small sample sizes, meaning a low number of participants.

They’re simply not broad enough to be representative of the US population.

This makes it hard to say that their lab results will be the same for everyone who goes out & buys an ab stimulator belt.

Overweight man wearing ab stimulator belt hoping to lose belly fat - heydayDo image

3. No severely overweight people used

A related problem with both of the Univ. of Wisconsin studies is that none of the people who received the ab stimulation were real overweight.

In the 2005 study, the participants receiving the ab stimulator had a BMI (body mass index) of 28 or lower.

And in the 2018 research trial, those in the high-intensity ab stimulator group averaged a BMI of 24.

This means that in 2005 none of them were very overweight, and in 2018 the participants had normal weight (BMI’s 24 & under are considered normal weight).

My questions about this are:

* Does an ab stimulator work as well sending electronic signals through inches of fat as it does on more slender people where the muscles are more easily reached?

* Who’s more likely to buy an ab stimulator?


4. Is the EMS intensity the same?

I also wonder if the ab belts that people can buy on Amazon or through those infomercials have the same degree of voltage intensity as the laboratory models used in those two studies.

This is important.

It has been observed in multiple studies that in order for the benefits of EMS to occur, the electric signal has to be powerful enough to allow

“subjects to obtain muscular contractions in excess of 60% of their maximal voluntary contraction (MVC)”, and

“must typically be in the range of 60-80% of MVC to induce changes”.


I couldn’t determine if the commercially available ab belts are that strong (60-80% of MVC) or not, from reading the product literature I gathered from the 5 most popular ab stimulator belt brands.


In his 2018 EMS study at Univ. of Wisconsin-La Crosse, researcher John Porcari wrote

“Many over-the-counter NMES devices do not deliver a strong enough stimulus to reach this threshold.”


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Some commercial ab belts proven weak & ineffective

In fact, previously back in 2002 the same UW-La Crosse researchers had tested an electronic muscle stimulation (EMS) product with an ab stimulator belt and belts for the arms & legs too.

They were made by manufacturers other than BMR/Slendertone.

In that 2002 study UW researchers concluded that those muscle & ab stimulator belts didn’t work, saying

“EMS had no significant effect on the any of the measured parameters”.


Those parameters were:

  • increased muscle strength
  • decreased weight
  • decreased body fat
  • improved muscle firmness & tone

And in their subsequent 2005 research trial they again mentioned their previous 2002 study, saying they

“found no improvement…using one of these commercially available stimulators. The lack of positive results was attributed to the poor quality of the stimulators themselves.”


Bottom line: Are the ones on Amazon as good as the ones used in those science studies?

Going off the results of the UW-La Crosse studies and reading the FDA’s page on muscle stimulators, I believe that the Slendertone brand might be.

And maybe the Flex Belt, since they have the same parent company, Bio-Medical Research.



Where EMS has proven itself

Athlete receiving electronic muscle stimulation from physical therapist while performing calisthenics

Here are three clinical research studies demonstrating the benefits of electronic muscle stimulation (EMS).

Soccer players increased kicking strength

In this study of soccer players, knee extension torque & ball speed from stationary kicking significantly increased after 5 weeks of electronic muscle stimulation on the players’ quadriceps muscles.


Even elite athletes increased strength

A systematic review was conducted of over 80 research studies relating to the effect of electronic muscle stimulation (EMS) on physical performance in elite athletes.

After EMS periods of 3-6 weeks, several important sports performance parameters all increased significantly.

A few of these areas were:

  • maximal strength
  • jumping
  • power
  • speed strength
  • sprinting

What surprised the researchers the most was the amount of gains that these elite athletes experienced. They noted

“the analysis shows that trained and elite athletes, despite their already high level of fitness, are able to significantly enhance their level of strength”.

Usually performers at their level are already at the top tier of performance, where not much room to improve is left.


Ab belt decreases postpartum pooch

Post-natal diastasis recti abdominis muscles (aka DRAM) is the technical term for the pooch belly that pregnant women often get after giving birth.

The two halves of their rectus abdominal muscle separate, causing the belly to bulge out in between them.

In this study, an ab stimulator belt was used on women with DRAM who were all approximately 2 months postpartum, who also did ab exercises.

The control group only did ab exercises.

After 8 weeks, both groups experienced significant improvement in reducing DRAM and in all other study categories.

The group receiving the ab stimulation improved more than the exercises-only group.

The improvement categories were:

  • DRAM (pooch belly) decrease
  • Body mass index (BMI) decrease
  • waist/hip ratio decrease
  • ab muscle strength increase

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Review of best-selling ab belts

As of the time I’m writing this article, these are the most popular ab stimulators being sold on Amazon:

The Flex Belt Abdominal Toner

Flextone Abs Stimulator Muscle Toner

Antmona Abs Stimulator & Muscle Toner

Slendertone Evolve Abs

OSITO EMS Muscle Stimulator Therapy Machine

The links open those ab stimulator product pages in separate tabs, if you want to compare prices & features.


Here are their current rating scores, according to the verified buyers who left a review: (out of 5 stars)

The Flex Belt Ab Toner        3.7⭐     65% (4&5-star reviews)

Flextone Abs Stimulator     3.7⭐     60%

Antmona Abs Stimulator    3.7⭐    63%

Slendertone (sev. models)  4.6⭐    80%**

OSITO Muscle Stimulator   3.9⭐    71%

** – Slendertone pulled their older models, and this one currently only has two reviews. Their previous ab belts had a 3.6/5 rating.


My personal take

I’ve product-tested & evaluated hundreds of pieces of home fitness equipment, and I’ve read & curated thousands of online owner reviews.

So that’s where I’m coming from with my observations below.


Weak buyer ratings & reviews

Those ab muscle stimulator star ratings and percentages of 4 & 5-star owner reviews are pretty poor when compared to numbers I see in other health & fitness categories.

And remember, these are the most popular/best sellers in the ab stimulator product category too.

The main complaints that I repeatedly saw were either:


1) “The ab belt didn’t work for very long”. Work in this context meaning it didn’t operate properly due to bad wiring, bad charger, cheaply made, etc., or

2) “The ab belt didn’t work”. Here, didn’t work means the ab belt failed to do anything to/for their abs.


Note: The ironic thing I noticed about most of these 2nd type of complaints was that the people were saying this after only 1 or 2 sessions(!), let alone after 8 weeks of 5 times per week like the schedule used in the successful research studies. 


Lots of knockoff brands & fake reviews

In looking at this product category in its entirety on Amazon, two things struck me: lots of copycat cheap imported brands, and lots of fake or incentivized* 5-star reviews.

Comes with the territory I suppose.

* incentivized  receiving free stuff for writing a 5-star review


Recommendation: Do your due diligence if shopping for an electronic muscle stimulator.

Read reviews from legit owners.

Look for brands that have been cleared by the FDA (as you’ll read about next.)

Woman receiving electronic muscle stimulation for her abs by a medical professional


What the FDA says about ab belts

The FDA (our Food & Drug Administration) has actually dedicated a page on its website to electronic muscle stimulators; that link takes you there.

This is because they regulate the direct-to-consumer sale of devices like ab belts, due to some of the shady advertising claims I wrote about earlier.

They explain that electronic muscle stimulator makers are required to demonstrate that they’re safe & effective for the things that the manufacturer is claiming in their marketing hype.

On that page of theirs, the FDA answer 10 questions they asked themselves, which help explain why they need to regulate the manufacturers of muscle stimulation devices.

It’s a pretty quick read and worth checking out if you’re planning on buying an ab belt.

A few of their quote-ables include:


Q. Do they really work?

A. “…no EMS devices have been cleared at this time for weight loss, girth reduction, or for obtaining rock hard abs.”


Q. Is FDA concerned about the unregulated marketing of these devices?

A. “Yes. FDA has received reports of shocks, burns, bruising, skin irritation, and pain associated with the use of some of these devices. Some injuries required hospital treatment.”


Q. Will it give me the same kind of effect that lots of sit-ups, stomach crunches and other abdominal exercises will?

A. “Using these devices alone will not give you “six-pack” abs…(it) will not…create a major change in your appearance without the addition of diet and regular exercise.”



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Ab stimulator FAQ

Here are answers to some of the common questions asked about the ab stimulator belt.


Does an ab belt reduce belly fat?

It is not possible to spot reduce fat from a specific part of our bodies.

This has been proven many many times over in studies like this one published in the Journal of Strength & Conditioning Research where the authors concluded

“Six weeks of abdominal exercise training alone was not sufficient to reduce abdominal subcutaneous fat and other measures of body composition.”


Translation: Ab muscle stimulation by itself doesn’t reduce belly fat.


So when you hear or read where someone is claiming you can “target” your belly fat with their _____ (whatever it is they’re trying to sell you), ignore them.

What they’re saying is untrue.


How much should I use the ab belt?

The research study where the ab stimulator provided the significant muscle strengthening & toning results had the participants use the stimulator 5 times a week.

For the first week they wore it for 20 minutes per session, for weeks 2-4 30 minutes, and for weeks 5-8 of the study they were wearing the ab belt for 40 minute sessions.


Does the ab belt cause muscle soreness?

Soreness can occur for some people after using an ab belt, since it is working your muscles by contracting them repeatedly, similar to like strength training or doing crunches does.


Does an ab stimulator burn calories?

Ab stimulators do not reduce calories. A better way to improve the appearance around your midsection would be to put yourself on a full body workout using weights. Doing this the muscle you add will burn more calories than the fat you’ll be getting rid of can.

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Wrapping Up

I hope this article on what ab stimulator belts can & can’t do is useful to you, and I wish you well on your fitness journey.

Let’s go.

– greg

About heydayDo

heydayDo author Greg Simon
Hi I’m Greg Simon. Fitness training & nutrition researching since 1982. Organic food & wine grower. Surfer. Congenital heart disease survivor (so far). Read more…
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