Nutritional deficiencies caused by a lack of a balanced diet.

Lack of physical activity from emphasis on diet only can increase the risk of heart disease.

Lack of variety in foods can cause boredom and frustration, and make it difficult to maintain the diet for more than a brief period.

Severe restrictions on the foods you can eat may make it difficult to establish and maintain a healthy diet in the future.

Many quick weight-loss diets are based on unfounded claims that may do more harm than good.

People with type 1 diabetes need daily injections to help them absorb glucose to use as fuel. Failure to take correct doses can lead to rapid weight loss.

Charity Diabetes UK estimates that up to one-third of young women with the disease miss injections to stay thin.

Doctors warn that the "diabulimia" eating disorder can lead to blindness, heart and kidney disease.

US doctors recently went public on their concerns about the practice.

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 rate of overweight babies has increased quite dramatically in 0- to 6-year-olds over a 20-year period," Dr. Matthew Gillman said.

Gillman was part of the study that looked at more than 120,000 children under 6 in Massachusetts.

"What was most surprising about our study is that we found the rate of among youngest children -- our infants -- was rising over this time," he said.

According to the study, overweight babies between birth to 6-months-old increased by 74 percent. Researchers said that translates into babies becoming overweight adults. It's an increase of 60 percent.

The researchers identified 560 people who were diagnosed with dementia between 1990 and 1994. They then found a group of people of similar age who did not have dementia.

They looked back at the weight of all of the patients over the preceding 30 years.

Among the women in the study, those who later developed dementia started off at the same weight as those who did not develop dementia, but then their weight drifted downward by a few pounds 10 years before the developed any dementia symptoms.

The weight of these women also went downward a few more pounds when the memory loss first manifested.

Chaffee, who has a 26-inch waist, had several health problems as a newborn. One of them, pyloric stenosis, prevents food from emptying out of the stomach. The condition and ulcers he developed in his esophagus reduced his ability to gain weight.

Chaffee weighed 8 pounds when he was 4 months old, and 17 pounds when he reached kindergarten, his mother said. He was up to 85 pounds at age 14, but couldn't participate in some activities, including swimming.

"He sinks like a rock," his mother, Kelley Chaffee, told the Post Register.

Since turning 18 his goal has been to go over 100 pounds. He achieved that on a diet that included 5,000 calories a day in protein shakes.

"Visceral fat is very bad for you," says Richard N. Bergman, a professor at USC's Keck School of Medicine. "It seems to have a more negative outcome on health than overall fat."

The evidence now is so compelling that some experts suggest it's time to forget about scales and weight loss and focus on waists and "inch loss."

Luckily, visceral fat doesn't appear to be a particularly stubborn enemy. Health experts have discovered that consistent, moderate exercise by itself appears to help the body rid itself of vast amounts of deep abdominal fat — even when the scales show the pounds aren't dropping very fast.

This emerging science carries a message for consumers: Measure your waist circumference. And reduce it if need be. Doing something about that paunch could help save your life.

That is probably the best news about visceral fat: It's not all that hard to lose, and losing even a little might make a big difference in cardiovascular health. Sit-ups and liposuction won't work (sit-ups merely tighten the muscle and liposuction only removes subcutaneous fat), but studies show that regular diet and exercise can lead to a substantial drop. "It's easier than reducing any other fat because the abdominal fat is metabolically very active," Sharma of McMaster University says.

In fact, studies show that people who lose only 10% to 15% of total body weight can still lose up to 30% of their visceral fat — and reap fast, important benefits. A 2001 study published in the American Journal of Clinical Nutrition showed that white and black women on a diet-and-exercise program lost 41% and 37% of their visceral fat, respectively, with a total weight loss of about 15%.

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.

The number of overweight children worldwide will increase significantly by the end of the decade, and scientists expect profound impacts on everything from public health care to economies, a study published Monday said.

Nearly half of the children in North and South America will be overweight by 2010, up from what recent studies say is about one-third, according to a report published by the International Journal of Pediatric Obesity.

In the European Union, about 38 percent of all children will be overweight if present trends continue — up from about 25 percent in recent surveys, the study said.

Most people know part of Fogle's story, he said, but don’t realize he started gaining weight in third grade. "I can trace it back to when I was given the best birthday present of my life: a Nintendo."

At that point, Fogle said, he started playing video games more and riding his bike and playing sports less. He became sedentary. With his love of video games, he developed a love of junk food.

"I usually had one hand on the controller and one in a bag of chips," he said. By the time he reached sixth grade, he was bigger than the other children, he said, and his father, a doctor, started to worry.

"They tried restricting my Nintendo time, but I found ways to get around it," Fogle said.

Just when we thought we couldn't get any fatter, a new study that followed Americans for three decades suggests that over the long haul, 9 out of 10 men and 7 out of 10 women will become overweight.

Even if you are one of the lucky few who made it to middle age without getting fat, don't congratulate yourself -- keep watching that waistline.

Half of the men and women in the study who had made it well into adulthood without a weight problem ultimately became overweight. A third of those women and a quarter of the men became obese.

All the 1,000 children studied were born between April 1972 and March 1973.

At age five, seven, nine and 11, parents were asked how much TV they watched. At ages 13 and 15, the teenagers themselves were questioned.

Between the ages of five and 15, children were found to watch an average of 2.33 hours of TV per weeknight. Aged 13 to 15, they watched an average of 24.6 per week. At each age, the amount of TV watched was consistent with the child's BMI.

The links were stronger in girls, which the researchers say may be linked to the differences in lifestyle and physical make-up of between teenage boys and girls.

Clinton said lawmakers should take a greater involvement in the fight -- setting higher standards for school lunches and eliminating junk food in school vending machines.

He called on the fast-food industry to shape up.

"You get good bulk, and it tastes good for the money ... but we cannot sustain it from a health care point of view," he said.

Clinton has made changes since his health scare. He said he has cut down on french fries, eats more fruits and vegetables and incorporates exercise into his mornings. He said he wants to teach that lesson to American children.

"The bottom line is we've got too many kids too overweight," he said, "and they're walking time bombs."

Weight Watchers received the highest overall rating. A nutritionally balanced diet, plus weekly meetings and weigh-ins for behavioral support, give this large commercial weight loss program the highest long-term adherence rate of any diet studied. This plan doesn't exclude any food group and its point system encourages consumption of low-fat, high fiber meals.

Slim Fast, which received the second highest overall rating, is recommended for people who don't like to cook—branded bars and drinks replace part of breakfast and lunch—and dieters need to prepare only one full meal a day. People on the Slim Fast plan lost the most weight in six months using products like 180-calorie shakes.

The Zone is high in protein and includes copious amounts of high-fiber vegetables. Many companies offer home delivery of "Zone favorable meals." It is recommended for those who want a short-term high protein diet plan.

Ornish offers ultra low-fat, high-fiber vegetarian meals, which provide fairly large portions for the low calories.

Atkins Induction and Atkins Ongoing Weight Loss are appropriate for people who want a short-term high protein diet plan. The Atkins diet worked very well in the short term, with results at least as good as our other top-rated diets. But its nutritional deficiencies—too much fat, and too little fiber and too few fruits—depressed its overall Rating and may have a negative effect on some people's health.

Eat high-bulk, low-calorie foods: This is a promising strategy for curbing hunger while keeping calories down. Such foods include fruits, veggies, and other water-filled foods such as soups.

Control blood sugar: One way is to stay away from starchy, easy-to-digest carbohydrates, such as refined flour, white rice, and potatoes, and avoid added sugar.

Eat plenty of high-fiber carbs, such as whole grains, fruits and veggies.

Measure portions and seek encouragement.