Obesity is on the rise with no end in sight. A Trust for America's Health and Robert Wood Johnson Foundation study showed that adult obesity rose in 16 US states and declined in none in the past year.

Now, 12 states have obesity rates over 30 percent, with Mississippi leading the pack at 34 percent. Only one state, Colorado, has an obesity rate under 20 percent.

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Four years ago, there was only one state with obesity rates above 30 percent. Twenty years ago, no state had an obesity rate above 15 percent.

Obesity has now become a major cause of preventable death in the US because it leads to heart diseases and diabetes.

So why has America gotten so fat in the last few decades?

One theory is sugar. The USDA has recently come out against sugary drinks (i.e. sodas) with the introduction of its MyPlate dietary guideline. Even before this development, vocal critics have already put the obesity blame squarely on sugar.

Robert Lustig, professor at UCSF, claims that sugar (more specifically, fructose and sucrose) is toxic and the human liver treats sugar in a similar way that it treats alcohol.

Sugar also disrupts the body's ability to regulate weight gain and satiety and thus makes people obese, according to Lustig. He said a calorie from sugar is not the same as a calorie from another source; instead, sugar calories are inherently more fattening.

He said a study showed that excessive sugar intake even adversely affects a person's ability to lose weight through exercising.

In the last few decades, sugar consumption has risen in tandem with obesity. Now, sugary drinks are the number one food source for caloric intake of Americans, according to Margo Wootan, director of Nutrition Policy Center for Science in the Public Interest.

Lustig said nutrition research decades ago identified fat (saturated fat, specifically) as unhealthy, which is correct. Now, many food products cut down on that.

However, they completely missed the boat on sugar, which has steadily made America fatter and fatter in the last few decades.

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