A body scanner could help fitness fans work out exactly how much of their bodies are made up of fat.
The scan can pinpoint the exact distribution of fat
Doctors could use the device - developed by UK scientists - to look for abnormal fat which may be putting their patients at risk.
Scientists at Lancaster University and the Institute of Food Research in Norwich used radiowaves to detect fat beneath the skin.
It is hoped that such machines could be commonplace in leisure centres one day.
The device works on the principle that the human body is a mixture of water and fat.
The amount of fat on a person can be calculated by working out their density using their exact volume and weight.
Other methods pass a tiny electrical current through the body - the level of resistance to the current can be used to estimate fat content.
However, none of these methods is particularly practical to be used in seriously-ill patients - or ordinary members of the public who need an easy way to find out the truth about their bodies.
The new method, revealed in New Scientist magazine, involves passing coils which create a radio-frequency electromagnetic field over the body.
The make-up of the object within the coil alters the phase of the field - and this can be measured and used to estimate the water content - and hence the fat content.
When this information is coupled with an exact measurement of the body's volume collected by four lasers sweeping across it, the researchers can in theory create a rough picture of not only the amount of fat, but also its location on the body.
Dr Henri Tapp, from the Institute of Food Research, told BBC News Online: "The technique is called magnetic induction tomography - it has been around for a while, but it is the first time it has been used this way.
"At the moment, we're still building the thing, and we'd offer it to other researchers with an interest in body composition.
"But, because the technology is relatively inexpensive, at some point in the future, we should be able to put something like this in a leisure centre and members of the public could use it on a regular basis.
"However, this is some years off yet."
While traditional measures of obesity, such as body mass index, can help doctors predict the risk of diseases such as diabetes or heart disease, there is increasing evidence that the precise location of that fat - whether it evenly distributed or located around the waist - also has a bearing.