A diet that's high in sugar, simple carbohydrates (white flour, potatoes, sugary drinks) and saturated fat is one of the chief causes of the obesity epidemic. More than one-third of American adults are obese, and kids are following the trend. An alarming 21 percent of adolescents 12 to 19 years old are obese, as are 18 percent of children 6 to 11 years old − double the obesity rates from the 1980s [sources: CDC, CDC].
What's the connection between Type 2 diabetes and junk food? Americans, on average, consume 22 teaspoons of sugar a day, much of it in the form of high-fructose corn syrup served up in soft drinks and candy bars [source: Boseley]. When the body breaks down these simple carbohydrates, blood sugar levels spike. That forces the pancreas to quickly release insulin so that cells can absorb and store those sugars. Frequent blood sugar spikes eventually wear out the body's insulin-producing cells, triggering Type 2 diabetes [source: Harvard School of Public Health].
Type 2 diabetes carries a host of health complications including heart disease, painful nerve damage, kidney damage, an increased risk of Alzheimer's, and foot infections that can require amputation [source: Mayo Clinic].
Even our mental health can be affected by a poor diet high in refined sugars, processed meats and high-fat dairy desserts. Researchers have found a strong connection between a junk food diet and higher rates of depression [source: Zeratsky]. High fat and sugar levels are known to increase inflammation and oxidative stress in the brain – which can disrupt the brain's chemical signaling [source: BBC News].
And what about junk food addiction? A growing body of research shows that obese adults and children exhibit classic signs of addiction − out-of-control binge eating, increased tolerance and withdrawal symptoms − that are usually associated with alcohol and drugs [source: Gray].
The U.S. federal government has tried to enact tougher regulation of junk food, particularly its marketing and availability to children. The U.S. Food and Drug Administration now requires restaurant chains and movie theaters to post calorie counts directly on their menus, and sugary soft drinks have been removed from most school vending machines [source: Tavernise and Strom].
Still, fast-food chains continue to spend billions of dollars marketing their high-calorie, low-nutrition foods to even the youngest children. In 2012, McDonald's alone spent 2.7 times as much money on advertising as all fruit, vegetable, bottled water and milk producers combined [source: UCONN Rudd Center for Food Policy & Obesity].