Bell has spent years studying how human beings store and use their adipose tissue, or fat. He has carried out studies showing that people who would be considered slim can have large quantities of fat within them.

'This is particularly true of men who have a slim build but who do little or no exercise,' he said. 'We know now that 40 per cent of people have fat infiltration of the liver, which is linked to so many other health problems.'

He said of Schwartz: 'He is slim, he's not overweight, but you can see there are some areas where there is a bit of a build-up of visceral fat. He doesn't have a lot of subcutaneous fat [the kind that lies just under the skin], but I can see there is quite a bit around the organs and some in the muscle.'

Thanks to this new technique, Bell and others are able to understand why appearances can be so deceptive. Someone like Schwartz, who is young, falls into the category of those who need to start changing their lifestyle. Unknowingly, he is on the way to becoming what is jokingly described as a 'Tofi' - Thin on the Outside, Fat on the Inside. Tofis probably need to worry more about their health than others, because the fat deposits they carry are hidden in the white fat that lies around their vital organs, streaked through their underused muscles, and wrapped around the heart. It is this fat that sends out the chemical signals which eventually lead to insulin resistance, diabetes and heart conditions, rather than the fat lying in dimples underneath the skin.

What really counts, says Bell, is how and where the body's energy supply is stored. Fat cells are extremely intelligent - 'versatile players', as the American obesity specialist Roger Unger called them - which hang on stubbornly even through crash diets. For years, doctors saw fat tissue as a kind of passive storage compartment, but new research has shown that the fat cells, or adipocytes, are dynamic beings.

In Japan, sumo wrestlers have been put through MRI scanners to look at their fat composition. Even though they have a BMI of 56 and are eating up to 5,000 calories a day, they have very little internal fat. 'They have low cholesterol, they have low insulin resistance and a low level of triglycerides [fatty acids],' said Bell. 'Their fat is all stored under the skin, on the outside.'

The NuMetrex Heart Sensing Sports Bra was launched by Textronics in December 2005, and was named 2006 Sports Product of the Year by the Sporting Goods Manufacturers Association. The garment features electronic sensing technology that is actually integrated right into the knit of the fabric, which picks up the heart's electrical pulse and radios it to a wrist watch via a tiny transmitter in the bra. It offers a new level of comfort and convenience for women wishing to monitor their heart rate while they exercise.

Textronics is currently working to expand the NuMetrex clothing collection to include a heart rate sensing shirt for men which will be released to market this fall. Also in development is a larger size heart rate sensing sports bras for women targeted for release in early 2007.

Half the mice were fed a vegetable-free diet and half the mice were fed a diet which included broccoli, green beans, corn, peas and carrots.

After 16 weeks, researchers measured cholesterol content in the blood vessels and estimated that plaques in the arteries of the mice were 38% smaller.

Although there was also a reduction in total cholesterol and body weight in mice fed the vegetable-rich diet, analysis showed that this could not explain the reduction in atherosclerosis.

Lead researcher Dr Michael Adams said: "While everyone knows that eating more vegetables is supposed to be good for you, no-one had shown before that it can actually inhibit the development of atherosclerosis."

The laser is able for the first time to heat up fat in the body without harming the overlying skin.

Using the Free-Electron Laser at selected wavelengths, scientists were able to heat the fat up, which was then broken down and excreted by the body.

Professor Rox Anderson, dermatologist at the Massachusetts General Hospital, led the experiment using pig fat and skin samples about two inches thick.

He said the results showed that selective photothermolysis - heating tissues with light - could have medical applications in the future, including treating acne.

People who survive a toxic encounter with carbon monoxide, one of the most common types of accidental poisoning in the United States, run a risk of death years later because of damaged heart muscle, according to a study published Tuesday.

The Minneapolis Heart Institute Foundation said a look at 230 patients treated for moderate to severe poisoning from the colorless, odorless gas found that 37 percent suffered heart muscle injury. Of that group nearly a quarter died within the next seven years.

"Most of us believed that since this was a one-time exposure to carbon monoxide, that if you were going to have problems you'd have them right away," said Timothy Henry, a physician involved in the study.

Dr Wilma Scholte op Reimer, of the Erasmus University Medical Centre in Rotterdam, the Netherlands, who led the study, said it was "unbelievable" so many carried on smoking after a life-threatening event for which the habit is a major risk factor.

"It makes me wonder if they are truly aware of the risk that they are taking," she said.

Dr Scholte op Reimer said there may be a difference between patients having the general knowledge that smoking is a bad habit, and understanding the risk they themselves faced.

She said it was important smokers had access to support from stopping-smoking programmes, and access to nicotine replacement therapies, if necessary.