Latest evidence suggests that internal fat, although invisible to the naked eye, is potently more harmful than external fat.

"Being thin doesn't automatically mean you're not fat," says Dr. Jimmy Bell, a professor of molecular imaging at Imperial College, London. Thin people can actually be fat at the same time, having a lot of internal fat stored around vital organs like the heart, liver or pancreas, possibly contributing to heart disease or diabetes.

A Canadian study has shown that people who sleep for an average of 7-9 hours per night are less likely to put on weight than those who have very little or lots of sleep.

The in depth study, which was published in the April 2008 issue of Sleep magazine, took a sample of 276 adults between the ages of 21 and 64.

Results from many previous studies indicate that obesity is strongly associated with several major health risks and that it contributes to the increased incidence or death, including those from various types of cancers. Over the past 20 years the rates of obesity have tripled in developing countries like China, India, and Russia. This is being attributed mainly to a greater abundance of 'cheap calories' and increasingly sedentary lifestyles. Trends toward increasing obesity are however most concerning in United States, where 28% of men and 34% of women can be considered obese (BMI over 30).