Devices in this category typically hit the skin with cold or thermal energy, in an effort to disrupt and diminish underlying fat cells. The machines can cost from $60,000 to about $110,000 — and that doesn’t include recurring use fees that some companies charge doctors for replacement treatment heads. Capital expenditures on the machines in the United States are expected to top $200 million by 2019, compared with around $73 million this year, according to projections from the Decision Resources Group, a health care analytics company. A session can cost consumers from $200 to several thousand dollars, depending on the type of device and the extent of the area to be treated.

“Physicians know there are patients who are willing to spend more money on noninvasive procedures than they would on an invasive procedure like liposuction,” April Lee, an aesthetics industry analyst at Decision Resources, told me. “As long as there is new technology, there will be people willing to try it.”

Oddly, the treatments aren’t aimed at the seriously overweight. Experts told me the ideal candidates are those who are already reasonably fit, exercise regularly, eat sensibly and just want to address an unwanted nubble here or there.

“If you are trying to lose 10 to 15 pounds, this is not for you,” says Dr. Mathew M. Avram, a dermatologist at Massachusetts General Hospital. “This is just sculpting areas to improve the appearance.”

The Food and Drug Administration vets the machines, but that doesn’t guarantee their effectiveness. For those manufacturers able to prove that their gizmos are comparable to devices that have already received federal clearance, the agency does not typically require rigorous, long-term scientific proof of benefit.

Image The Slendo Massager.

In fact, some methods for corroborating machines’ fat-busting claims in marketing — like before-and-after photos, or tape measures — can be quite unreliable. A person inhaling and sucking in her abdomen could have a waistline that is several inches smaller than when she is exhaling.