Professor Alain Dagher from the Montreal Neurological Institute and McGill’s Department of Neurology began Friday’s talk by explaining why it’s hard to be a koala.
“It has nothing to learn about the world in order to feed itself,” Dagher explained. “The leaves of the eucalyptus tree have all of the nutrients that it needs.”
Because of this, if the koala were to be placed in an environment where there was no eucalyptus, it would likely starve. Omnivores, on the other hand, can eat all foods, a trait that has allowed two species of omnivores—humans and rats—to exist almost anywhere.
However, when entering into a new environment, the brain must learn about its new food sources. Omnivores will use their brain to respond to the body’s needs. If the body needs salt, the brain will trigger a response to seek out salty foods. However, the body will have had needed to be previously exposed to those foods high in salt content. In particular, it’s crucial to learn which foods are high in calories, Dagher explained.
“Nothing in the brain makes sense except in the light of eating,” Dagher said. “You can consider the brain as an organ designed to find food.”
Today, some are going so far as to say that hunger is an addiction to food.
From an early age, we are conditioned to associate hunger and feeding via reward pathways. Babies with empty stomachs experience discomfort, cramps, and anxiety that cause the baby to cry. In response to this, the mother will feed the baby, relieving those pains. This cause-and-effect conditions the baby to associate food with pleasure.
Furthermore, because of the risk associated with going out to seek calories, humans want to store calories to be able to access and use them later. So no matter how satiated a person may feel, the sight of food will still induce cravings.
“The sight of food can induce craving—even when we’re not calorie deprived—and hunger is learned,” Dagher said.
These traits, Dagher explained, are pushing people to label hunger as an addiction to food. When a person is addicted to drugs, the sight of the drug induces cravings. For example, the sight of a cigarette will trigger a person trying to quit smoking.
Furthermore, the ability to control these cravings is based on what are often called the ‘big five personality dimensions’. The five factors are openness, conscientiousness, extraversion, agreeableness, and neuroticism.
“The important ones are conscientiousness, neuroticism, and extraversion,” Dagher said.
Those who have high conscientiousness and neuroticism are more likely to control their emotions, self-regulate, and will therefore be more likely to have a low body mass index (BMI). On the other hand, those who score high in extraversion were more likely to have low self-regulation and high impulsivity. These people are more likely to have higher BMIs and will live on average 10 years less than those with high conscientiousness.
There is also an economic variable for food consumption.
“Cognitive and emotional factors can overcome [your] taste and homeostatic system and control your behavior,” Dagher said. “A good example of this is allostasis, [the ability to predict future needs.]”
According to Dagher, if a person is going on a hike, they will bring water with them, despite not immediately being thirsty, so they are planning for the future. This also applies to going to the supermarket, when we buy groceries for the week. Unfortunately, today, the less healthy foods—and therefore higher caloric foods—are cheaper, making people more inclined to purchase them.
According to Dagher, 40 per cent of the recent increase in weight in the U.S. can be attributed to reduced food prices. As the cost goes down, we eat more.
When this was necessary for basic survival in an agricultural society, it made sense to over-eat when food was cheap, and weight gains and losses correlated with harvest cycles.
“If you’re wired to over consume when food is abundant and you have a society where food is always abundant—as opposed to certain periods of the year, especially processed food—you’re going to have significant weight gain,” said Dagher.
So are we addicted to food? It’s hard to say, explained Dagher, because addiction doesn’t have a clear definition. But in order to further understand trends in obesity, it’s vital to understand how and why we respond to food.