What’s the Secret of the Slim?

According to the World Health Organization, worldwide obesity has nearly doubled since 1980, while 65% of the world’s population live in countries where overweight issues and obesity kill more people than being underweight.

Still, even in today’s world, with its abundance of food, some people manage to stay slim. Why are they able to do that? What’s different about their behaviour? Psychologists are interested in such questions. Knowing the answer would make it possible to use the success formulas of the slim to help those worried about their excess weight. Preventive means could be found as well, enabling one to do something before the bloated waist makes overeating evident.

Being slim has certain advantages over being overweight in health and in fashion, as shown in the caricature “Following the Fashion” by James Gillray in 1794. Image credit: Wikimedia Commons

Uku Vainik, a doctoral student of psychology at the University of Tartu, is studying mental factors that influence people’s eating behaviours. An analysis by Vainik and his colleagues from Montreal, published in the Neuroscience & Biobehavioral Reviews journal, demonstrated that self-control and food-related motivation are the main mechanisms that regulate eating. Memory in general, as well as linguistic abilities, have no importance when it comes to eating.

“More capable self-controllers can more likely plan their lives better, including escaping the temptations of everyday life, and that’s why they are more often at a healthy weight. On the other hand, higher food-related motivation makes the meal more desirable, and that’s why it’s seen as a factor that increases weight”, Vainik explained.

What is this “food-related motivation”? When this parameter is higher, the person is better at spotting images and food smells in the environment; he or she is ready to make a greater effort in the name of food. This trait was probably necessary for survival in the time of hunter-gatherers, making it possible to stay alive when food was scarce.

But in today’s world, with supermarkets full of food, greater food-related motivation can be harmful more often than not, as it makes us too capable of spotting food. And as long as the environment does not improve, we have to use our self-control to manage the situation. Some studies have researched both self-control and food-related motivation. The results indicate that better self-control can provide protection for high food-related motivation. It’s likely that better self-control enables the person to plan his or her behaviour before coming into contact with attractive food, as well as to prevent the situation altogether or eat enough healthier food beforehand, when needed.

According to Vainik, self-control doesn’t always bring positive results. People who strictly limit their eating, including starving themselves, are not very successful in the long run. Their efforts will be undermined by the third component of eating regulation – the sensation of hunger.

When hunger is increased, food-related motivation will increase too, making self-control harder and harder to achieve. In the end, self-starvers often cannot fight the tension anymore and end up eating anything possible, including unhealthy things, rendering self-starving counterproductive.

To some extent, body weight is also affected by one’s combination of genes. Recently, the UT Estonian Genome Center signed a cooperation agreement with Nestlé Institute of Health Sciences to study the molecular and genetic factors regulating body weight. “For example, it is widely known that people who eat identically can gain or lose weight at a different rate in spite of equal physical activity. The exact reasons for this are not yet known”, said Andres Metspalu, Director of the Estonian Genome Center.

Vainik U, Dagher A, Dubé L, & Fellows LK (2013). Neurobehavioural correlates of body mass index and eating behaviours in adults: a systematic review. Neuroscience and biobehavioral reviews, 37 (3), 279-99 PMID: 23261403