Scientists never really thought that a person could become hooked on sweets like they were a drug. Now a batch of findings is making researchers reexamine the concept.
Sugar addiction has long been joked about. Most researchers, however, believed you could not get hooked on sweets and lose control over consuming them, as if they were drugs. Studies are now making some scientists revisit the idea. The results do not indicate that donuts are in the same category as addictive drugs like heroin, alcohol or nicotine, but they do suggest that some brain actions and characteristics associated with the intake of sweets and drug addiction may overlap. The findings are leading to:
• A better understanding of how the brain controls food intake and how this system may go awry.
• New ideas on how to treat people with extreme compulsions to overeat sweets.
Studies that focused on brain chemicals, known as opioids, provided some of the first clues that an overlap may exist between sweets and drugs. Some addictive drugs like heroin or morphine activate the opioid system to produce a pleasurable response that many believe helps fuel a longing for more drugs and is key to the addiction process.
In one study, compounds that blocked the activity of opioids made animals less interested in eating meals, particularly sweetened versions. Researchers found similar results in tests of humans with eating disorders like bulimia, marked by a habit of binging on foods that are typically sweet. The blockers cut in half the consumption of sweets packed with sugar and fat including candy bars and cookies. The intake of low sugar, low fat snacks such as popcorn, saltines, breadsticks and pretzels did not decrease. Some believe that the studies hint that sweets, like some drugs, have a pronounced affect on the brain’s opioid system (see image), although direct proof is still lacking.
Whether through opioids or some other brain chemical, the scientists suspect that sweets like drugs can activate an “incentive system” in the brain that helps reinforce behaviors. Activation by food is generally beneficial. It makes us want more and keeps us alive. Sweets, however, packed with calories, may create extra activity that helped us in primitive times when food was scarce, but is not needed today.
Recent behavioral tests in rats further back the idea of an overlap between sweets and drugs. Drug addiction often includes three steps. A person will increase his intake of the drug, experience withdrawal symptoms when access to the drug is cut off and then face an urge to relapse back into drug use. Rats on sugar have similar experiences.
Researchers withheld food for 12 hours and then gave rats food plus sugar water. This created a cycle of binging where the animals increased their daily sugar intake until it doubled. When researchers either stopped the diet or administered an opioid blocker the rats showed signs common to drug withdrawal, such as teeth-chattering and the shakes. Early findings also indicate signs of relapse. Rats weaned off sugar repeatedly pressed a lever that previously dispensed the sweet solution.
Plans are under way to study binge eaters and further determine whether molecular and behavioral signs common to drug addiction exist. If confirmed, the research could lead to new ideas for treating eating disorders. It also may give you more incentive to steer clear of that tub of chocolate fudge icecream. Well maybe.