METRO BEIJING / METRO BEIJING
Junk food mania
Why are processed snacks so addictive?
Published: May 12, 2015 05:53 PM

Processed snack foods are often high in sugar, fat and calories. Photo: Li Hao/GT

 

"I think some foods are magic, you just can't stop eating them," said Huang Ying, a 26-year-old Beijing shop assistant and self-confessed junk food addict. "Last night while watching TV, I ate about 1 kilogram of fried melon seeds. I didn't even realize [I had eaten so much] until there were almost none left in the bag!"

Other snack foods she finds impossible to put down, said Huang, include potato chips, peanuts and cookies. She said that half of her shopping trolley when she goes to the supermarket is made up of junk foods, and she also frequently buys snacks on the Internet, from fried broad beans to marble chocolate to jelly drops and dried fruits.

"I tend to like small, bite-sized snacks," said Huang.

"I thought because they are so small, it would be easier for me to control the quantity that I ate, but I've realized I'm wrong."

According to a Yahoo Health report last month, processed food companies engineer their products to trigger the neurological pleasure centers in the brain, with many junk foods loading up on salt, sugar and fats.

A study published in Nature Neuroscience in 2010 suggested that binging on junk foods is as addictive as cocaine or heroin. Because of their high calorie and high fat contents, excessive consumption could lead to obesity and other related health complications, according to the study.

Nutritionists suggest that people should learn to curb the desire for junk foods and replace them with healthy foods such as fruit. Photo: Li Hao/GT

 

Why so irresistible?

"There are reasons why people love junk food and call it 'magic,' said Shi Jie, a Beijing-based nutritionist.

"The taste, the texture, the smell and even the sounds produced by these foods all make people want to keep eating."

Shi said that many processed junk foods use excessive seasonings to create strong flavors, with spicy and sour flavoring agents that trigger the appetite particularly popular in China.

"Strong flavors stimulate people's taste buds and send signals to [pleasure centers] in the brain," she said.

According to Shi, when strong flavors hit the taste receptors on the tongue and mouth, a series of neurological reactions in the brain affecting the entire body are triggered. Heartbeat, production of saliva, and perspiration all increase, and the stomach and intestines become more active.

At the same time, the brain releases endorphins, a chemical that produces a feeling of euphoria. 

Potato chips and other fried snacks also frequently contain high quantities of monosodium glutamate (MSG), an additive that enhances savory flavors, said Shi.

"Chips and other puffed snacks are usually heavily covered by seasoning, so you can't help licking your fingers when eating them, which can bring extra pleasure," said Shi. "The heavy amount of MSG cheats your nose and makes the food more attractive and appetizing."  

Junk foods are also often constituted and packaged in such a way to entice consumers into eating more, said Shi.

Shi gave the example of M&Ms, which due to their small individual portion size, can deceive people into thinking they are eating less than they actually are.

"When people eat, they subconsciously estimate how much they have eaten in order to control their food intake," said Shi.

"When you eat foods that require a lot of chewing, your brain tells you that you have eaten enough and creates the feeling that you are full."

Conversely, when one doesn't have to chew strenuously, as with M&Ms, it takes longer for the brain to send a signal that one is full, said Shi, causing the person to eat more. 

The shapes of foods also influence their addictiveness. In 2013, according to a Yahoo report, Cadbury reshaped their chocolate bars to be rounder, with the effect that testers thought the chocolates tasted sweeter, even though the recipe hadn't changed. The report noted that the rounder shape "fool[ed]" people's taste buds, causing them to overeat."

Dangers of addiction

In 2010, a study conducted by scientists at the Scripps Research Institute in Florida and published in Nature Neuroscience found that the addictive properties of junk foods were comparable to those of drugs like cocaine and heroin.

The scientists divided a set of laboratory rats into three groups, one of which was given healthy food, another was given restricted amounts of high sugar and fat laden food, and a third that was given unlimited amounts of high-calorie junk food, including cheesecake and chocolate snacks.

They found that the rats given unlimited amounts of junk food subsequently needed more stimulation to achieve the same level of pleasure as the animals on healthier diets when electronically stimulated. When the scientists changed the diet pattern of this group to a healthy one, they found that the rats simply refused to eat.

Paul Kenny, the lead researcher on the study, told the Telegraph that the findings proved that junk food is "addictive."

"It presents the most thorough and compelling evidence that drug addiction and obesity are based on the same underlying neurobiological mechanisms," he said.

Huang likewise compared her dependence to processed snack foods to that of a drug addiction.

"I think every drug addict knows that drug abuse is wrong but they can't control themselves," said Huang.

"I know that eating too much unhealthy snacks leads to becoming overweight, but when I run out of snacks, I feel nervous and anxious, even irritable."

Shi said that excessive consumption of unhealthy snack foods could lead to malnutrition, obesity, diabetes and cardiovascular diseases.

Given that many people snack when surfing the Internet or watching TV, the combination of an unhealthy diet and prolonged periods of inactivity could further increase the risk of health problems, Shi said.

Beijing-based psychologist Li Jianzhong said left untreated, compulsive overeating may also lead to mental health disorders, such as bulimia nervosa and depression.

"I think food addictions and people's mental and physical conditions are closely related," said Li.

Healthier alternatives

Li said that a simple way to control one's desire for eating junk foods was to desist from buying too much, and to remove a set quantity from a package before one started eating to control the intake.

For those who believed they were addicted to junk foods, Shi advised replacing unhealthy snack foods with healthier ones.  

"People who can't stop eating junk foods might just be used to their unhealthy diet pattern," said Shi.

"[They should] try to get their sugar fix and pleasure from eating natural foods instead of processed ones."

Shi recommended fruits, juices, and snacks made from grains that are high in fiber and low in fat as good alternatives to unhealthy junk foods. 

It was also important that those addicted to junk foods be alert to what they are eating and strictly limit their daily consumption of unhealthy foods, said Shi.

"If eating too much junk food has already led to an increase in body weight, then it is necessary to quit," said Shi.