While most people know that the U.S. Food & Drug Administration (FDA) regulates, well, food and drugs, some people may not realize the federal agency also regulates medical devices. According to its website, it does this to assure the "safety and effectiveness" of such devices, and it endeavors to monitor the sale and use of everything from simple tongue depressors to complex programmable pacemakers. 

Among the more recent medical devices that have received FDA approval are electronic ab stimulators - devices meant to help users strengthen, tighten and tone their core muscles. 

What are ab stimulators?

The first thing to understand about ab stimulators is that they are part of a broader family of muscle stimulators known as electronic muscle stimulators, or EMS devices. 

EMS devices are often used for physical therapy or rehabilitation purposes. Doctors provide or prescribe them to patients as treatment for muscle spasms, to improve range of motion, to prevent muscle atrophy, or to aid with muscle recovery after a patient has experienced a significant injury or major surgery. "Electronic muscle stimulators have been used by physical therapists to treat injured muscle tissue for decades," says Lori Shemek, PhD, a certified nutritional consultant based in Dallas and author of "How to Fight FATflammation."

More recently, a type of EMS device was also FDA approved to help people obtain firmer abdominal muscles. These devices are known colloquially as ab stimulators. Shemek explains that such devices use electrical pulses or stimulation to force one's muscles to contract. "This contraction is what produces ab growth," she says.

Do ab stimulators work?

Because of this, "ab stimulators really work," Shemek says. She explains that ab stimulators can help strengthen and tone ab muscles, "but there is no evidence that it will substantially change a person’s body such as give you those 6-pack abs without also incorporating a healthy diet and sufficient exercise." Even when ab stimulators work as intended, she says, it takes "about 2 months to see any perceptible change."

Natalie Allen, MEd, RDN, a clinical associate professor and a team dietitian in the athletics department at Missouri State University, notes that some ab stimulators also claim to reduce waist size and improve posture, "but studies are limited and do not show significant improvements in these areas." Indeed, per the FDA, many of these devices do not have some of the advantages they claim to have. "At this time, FDA is not aware of scientific information to support many of the promotional claims being made for numerous devices being widely promoted on television, infomercials, newspapers, and magazines," the agency notes. 

At the same time, the federal agency does say that when electrical current is applied to muscles through ab stimulators, "it may eventually result in muscles that are strengthened and toned to some extent, but will not, based on currently available data, create a major change in your appearance without the addition of diet and regular exercise."

In addition to ab stimulators like the FDA-approved Slendertone Flex that uses electrical pulses, there are also FDA-approved devices like the Emsculpt Neo that function a bit differently. "Unlike traditional ab stimulators, the Emsculpt Neo utilizes a different form of stimulation known as high intensity-focused electromagnetic energy combined with radio frequency," explains Lisa Espinoza, MD, an aesthetic physician and medical director at La Chele Medical Aesthetics in Pennsylvania.

What are the disadvantages of ab stimulators?

While both of these devices are FDA approved, many available ab stimulators are not, and may carry some risks. The FDA notes that it has received "reports of shocks, burns, bruising, skin irritation, pain and interference with other critically important medical devices (such as pacemakers) associated with the use of unregulated (ab stimulator) products." It adds that unregulated ab stimulators may also have safety problems associated with cables and leads which "can lead to accidental shock and electrocution by users and other household members, including children."

Even when such devices don't cause serious harm, Espinoza says many unregulated ab stimulator devices promise results that are often "too good to be true," and that it's best to receive physician-monitored care or use physician-recommended devices when considering the use of electronic muscle stimulators.

Shemek agrees, stating that it's also important not to overuse ab stimulators and to take breaks between use. "Muscles need time to recover, which is an important and even critical part of why the abs become larger and stronger," she says. Allen recommends an overall more natural approach to goals of becoming physically fit. "Walk, run, hike or bike," she advises, "and focus on a healthy diet loaded with fruits, vegetables and lean protein to improve overall health and lose weight everywhere, including your abs."

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