In a paper published in Nature on February 1, the University of California, San Francisco researchers argue that increased global consumption of sugar is primarily responsible for a whole range of chronic diseases that are reaching epidemic levels around the world.

It's going to require public policy that gently guides people toward healthier choices and uses brute force to remove sugar from many processed foods, said Dr. Robert Lustig, a pediatric endocrinologist at UCSF.

Lustig has written extensively about the role he believes sugar has played in driving up rates of chronic illness such as heart disease and diabetes. Excessive sugar, he argues, alters people's biochemistry, making them more vulnerable to metabolic conditions that lead to illness, while at the same time increasing people's craving for sweets.

It's sugar, not obesity, that is the real health threat, Lustig and his co-authors -- public health experts Laura Schmidt and Claire Brindis -- say in their paper.

They note that studies show 20 percent of obese people have normal metabolism and no ill health effects resulting from their weight, while 40 percent of normal-weight people have metabolic problems that can lead to diabetes and heart disease. They contend sugar consumption is the cause.