Life Lines by Dr. Dolittle

Sponsored by the American Physiological Society

The evolution of sugar addiction

Photo of Santa Claus captured by Jonathan Meath – Jonathan Meath, CC BY-SA 2.5

I have been opening Christmas cards and pondering the science of sugar addiction, admittedly while snacking on sugar cookies – ‘tis the season after all! Excess consumption of highly palatable (i.e. quite tasty) foods as well as sedentary lifestyles are thought to be at the root of the current obesity epidemic. In fact, it is thought that as many as 30% of people living in developed countries are either overweight or obese. While I cannot speak to his exercise habits as I have never actually been to the North Pole, I began wondering whether Santa Claus may actually have a sugar addiction? And if he does have a sugar addiction, is it really his fault? After all, delivering presents is hard work and it is not like kids are setting out healthy meal options for him. Think about it…how many cookies does he consume each Christmas Eve? It is truly mind blowing to think about.     

I found a review published in Frontiers in Psychiatry that explored the question of sugar addiction and how it may have evolved in humans. Considering the obesity epidemic is a rather new one, what happened in our history that could have caused it? Our rather sedentary lifestyles are often blamed for this trend as it reduces the energy we use. Another idea is that perhaps the quality of our food has changed such that people are eating more palatable foods, which are higher in sugar and fat. It is these foods that are thought to be addictive. I mean can you really eat just 3 cookies as the serving size suggests?  

From an evolutionary perspective, fat tissue in animals is very important for survival as it provides a readily available source of energy when food may be scarce or hard to find. It is thought that prehistoric people who were better equipped to store fat, may have been more protected during times of fasting that those who were not as adept at storing fat. That all changed, however, during the agricultural revolution when humans began to grow their own food in large quantities and then again in the industrial revolution that allowed for mass production of food and a turn towards more affordable – and palatable – ingredients.

So, where does that leave us today? Well, the authors of the paper in Frontiers in Psychiatry suggest that our brains may still be wired to consume excess food when it is readily available to prepare ourselves for a potential fasting period – that often doesn’t come in the modern world. In fact, researchers have identified several genes associated with obesity and our love for sugar (I must have extra copies). For many, sugar intake also activates reward centers in the brain that make us feel good about eating it – similar to drug addiction. However, this reward system appears to be impaired in people and animals who are obese, which may lead to overconsumption.

This reminds me of another story I came across a couple of years back about a zoo that had to regulate the fruits they were feeding primates and pandas because the animals were gaining weight and developing tooth decay. It turns out the fruits they were offering the animals were the same as those widely available in the grocery store, which are genetically modified to be larger and contain a lot more sugar compared to wild ancestral fruits. Although, the sugar in fruits (fructose) is healthier that that found in candy. The problem was that the animals were choosing to consume mainly fruits and would ignore other foods resulting in an imbalanced diet.  

So, is sugar addictive? It would appear so. Although, researchers argue over whether sugar intake alone could contribute directly to obesity – the consensus being it does not, although sugar-sweetened drinks specifically are linked to weight gain.

Maybe I will just have one more cookie…    


DA Wiss, N Avena, P Rada. Sugar Addiction: From Evolution to Revolution. Frontiers in Psychiatry. 9:545, 2018. Doi: 10.3389/fpsyt.2018.00545

Sydney Morning Herald

Categories: Agriculture, Aquaculture, and Livestock, Diet and Exercise, Exercise, Intelligence and Neuroscience, Urbanization

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