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Why Our Brains Love Sugar - And Why Our Bodies Don't

How sugar affects our brain chemistry making us want more and more.

“That glazed doughnut is calling my name. Oh yes, it is! It’s so sweet and pink and full of sprinkles. I long to taste those delicious sweet tidbits melting in my mouth, giving me a rush of pleasure and energy and making everything okay even when it isn’t.”

How many of us have had this feeling around mid-afternoon on a particularly grey and miserable day, when nothing seems to be going our way? I know I have! Longing for the comfort of a sweet treat, a blanket, a cup of coffee, and a reality show on the TV. Just wanting to check out for a while when life gets too demanding and difficult. And if we do this occasionally, we can just call it a “Mental Health Day” and leave it at that. We don’t need to buy into those Sugar Nazis foretelling gloom and doom if we eat one doughnut, especially if we turn off the TV for a bit and eat it mindfully

On the other hand, if this is our way of life or our habitual way of coping with stress, or, even worse, if we starve ourselves for a week or two, then give in and binge with half a dozen donuts, all the while feeling intense shame and self-disgust, we can get ourselves into a lot of trouble. In this case, we may be addicted to sugar. And, unlike other addictions, we can’t just stop eating or stay away from all the things that remind us of sugary food, because we have to eat to live and the sugary stuff is all around us, from the grocery aisle to Pinterest! Just look at the facts below.

The facts

  • The average American eats 156 lbs of added sugar a year. That’s more than I weigh, and, I must admit, the thought of eating my whole body weight in sugar each year is really gross!
  • We consume almost 500% more soft drinks than we did in the 1940s, according to a US Department of Agriculture Study published in 1999. Approximately half of the added sugar we consume today comes from soft drinks, sports energy drinks, fruit drinks, and the like. On the positive side, consumption is 40% down since its all-time high in the 1970s.
  • Research studies have linked excess sugar consumption to dangerous levels of LDL cholesterol (the bad type!), increased plaque deposits in the arteries, and breast and colon cancers. High fructose corn syrup — that insidious ingredient found in many salad dressings, ketchup, coffee creamers, etc. has been linked to increased heart disease and stroke. There is evidence that some tumors have insulin receptors that feed on glucose.

Is sugar craving an addiction?

Whether sugar actually is an addiction is controversial. The self-help industry has been singing this tune forever, cashing in on our fears and feelings of being incompetent and unhealthy. Yet scientific evidence is more recent, and mostly with rats, and the brains of people who are already obese. That doesn’t necessarily generalize to what will happen to Thin Sally or Athletic Larry if they eat donuts for a couple of weeks.

On the other hand, if you find brain chemicals convincing, the following is food for thought:

Neuroscientists have shown, using fMRI to scan the brain‘s activity in real-time, that sugar leads to dopamine release in the nucleus accumbens — an area associated with motivation, novelty, and reward. This is the same brain region implicated in response to cocaine and heroin.

Nora Volker, a researcher at the National Institutes for Drug Abuse has shown, using brain imaging, that there are similarities in the brains of obese people and those of drug addicts and alcoholics. This is indirect evidence, as we don’t know that sugar consumption caused this effect.

  • Nicole Avena, Ph.D., a Princeton researcher has shown that rats deprived of food for 12 hours and then given sucrose added to their regular food on a regular basis showed signs of bingeing, and increased searching for the sucrose (craving), These effects continued even after the sucrose had been withdrawn for one month. Withdrawal also occurred including symptoms of depression, anxiety, and increased aggression. Interestingly, the rats did not become obese — they cut down on regular food to compensate for the sucrose. Also, these effects were not shown in rats deprived of food and given just their regular food without sucrose.
  • Research suggests that sugar can lead to changes in dopamine receptors, such that tolerance develops — more of the substance is needed to get an effect. A decrease in some types of receptors (D2) occurred, which suggests an overall decreased ability to get pleasure from other substances and experiences. This could make the person or animal more dependent on sugar for pleasure and reward since the light of other experiences is dimmed.
  • Sugar consumption also leads to the release of endogenous opioids in the brain; leading to a rush of pleasure, similar (although not of the same magnitude) as injecting heroin. Interestingly, heroin addicts show increased cravings for sweets when they are first abstinent. This effect, known as cross-tolerance, shows that addiction to one substance makes it easier to become addicted to another substance that may use the same brain chemistry.
  • While we don’t know for sure that the same effects would occur in humans as animals, it is possible that eating too many sugary foods could lead to cravings, withdrawal, tolerance (needing more to get an effect), and preoccupation with finding the favored food. For me, this suggests the need to cut down on added sugar in all of its processed forms and start substituting it with the natural sugars found in fruit that do not have these toxic effects. Overcoming any kind of addiction or unhealthy habit takes time and commitment. In the next post, I will suggest some strategies that work.
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