The science behind hunger, desire, and overweight
The world seems to be at a paradoxical crossroad on the issue of hunger. On the one hand, almost 800 million people or a whopping 10% of the world's population are facing severe hunger and undernourishment. They are hungry but have little or no food to eat. On the other hand, almost 2.1 billion people are obese or overweight. That means when they are hungry, they have too much to eat. Both ends of the stick suffer from the irresistible hunger stimulus in opposite dimensions. One thrives from overfeeding as a result of excess. The other group wallows in painful short supply.
It would seem then that the world's hunger problem would be solved, perhaps dubiously if we could all conquer the hunger for food. A wonder pill or magic formula may be invented in the future that could deal with the challenge of hunger once and for all. It will deal a double death blow to the lucrative weight loss industry.
But then the question arises: Is this a realistic wish or is it a fool’s paradise? Before we arrive at that Utopian destination, it will be most instructive and beneficial to first get a deeper understanding of the science and the psychology of hunger.
The dictionary defines hunger as a compelling need for food or the painful sensation and state of weakness caused by the need of food. The irresistible craving for food is one of the common denominators of the entire human race as well as the animal kingdom.
Rich or poor, king or servant, strong or weak, sad or happy, big or small, we all get hungry, whether we like it or not. Hunger is a default position in the human body mechanism and is so normal that we hardly ever ask why we get hungry. People hardly question the reason and the psychology of hunger.
Science searches for answers
Thankfully, science is getting closer to a more complete understanding of the mechanisms behind hunger.
The instinctive hunger for food to fuel our bodies for basic survival is known as homeostatic hunger, and it is driven by simultaneous signals. When our energy levels are running low, the body hormones are triggered and the level of ghrelin, a particular hunger hormone starts to increase. That, in turn, creates a physiological sensation that propels the frantic search for food. It automatically starts dropping as soon as eating commences and a different set of signals are sent to the brain that takes away the hunger pangs.
The hunger battle then is both mental and physical. Hunger and cravings are propelled by the body and mind. The signals all come from within us and are not conditioned by the presence of food or other appealing external stimuli. Our brain then is the control tower in the hunger chain, not our abdomen or taste buds. The hypothalamus is the section of the brain tissue that stimulates us to search for food. It can quickly interpret the signals flowing from the special cells lining the small intestine and the stomach when their contents are low.
Another important hunger signal is our level of blood glucose. Insulin and glucagon are hormones made up in the pancreas and help to retain the blood glucose levels. Strong signals or alarm elks are wired to the hypothalamus in the brain, when hunger deprives the body of vital energy.
After eating, the blood glucose level rises and the hypothalamus picks up the signals and puts up signage indicating full. Even when our bodies send these strong hunger signals, our bodies may choose to ignore them. This is where medicine, science and sometimes unorthodox health programs attempt to interject these signals and disrupt the communication flow between the body and the brain, all to mask the hunger signals or magnify them as the case may be.
This control factor and ability to confuse the hunger hormones plays a key role tackling obesity, which the World Health Organization has classified a global health epidemic. A recently published Lancet survey, revealed that over two billion people in the world are now overweight or obese.
Worldwide obesity has more than doubled since 1980. In 2014, over 41 million children were obese, while a startling 39% of the entire world adult population was overweight. Contrary to common assumptions, more people around the world are dying more from obesity than malnutrition and being underweight. According to the WHO, the major cause of obesity is simply the lifestyle induced excess consumption of calories and energy-dense foods, disproportionately balanced against decreasing physical activities and exercises.
Dr. Christopher Murray, director of IHME and a co-founder of the Global Burden of Disease (GBD) study, revealed that “obesity is an issue affecting people of all ages and incomes, everywhere. In the last three decades, not one country has achieved success in reducing obesity.” He called for urgent steps to be taken to address this public health crisis.
Although the USA has about 78 million overweight adults and 13 million overweight children, it is only the 12th most obese nation in the world. Palau, Nauru Samoa and Tonga, all in the Pacific Islands are amongst the top five most obese nations in the world. Oil rich Qatar and Kuwait are also in the top 10. This has been attributed to their penchant for calorie loaded foods and increasing number of fast foods restaurants in the region.
Luckily, science is offering some hope in this battle of the bulge! A new study by a team of scientists at the Beth Israel Deaconess Medical Center (BIDMC), has been conducting a study on how certain external signals trigger cravings and influence eating habits. By manipulating a particular class of neurons and creating a new imaging approach, the research team has pinpointed a route by which neurons that trigger hunger and, in turn, influence other distant neurons that determine how we respond to food-related signals.
The research findings confirm that the insular cortex of the brain dictates our level of attraction to food. This brain part goes on overdrive in obese and overweight people. Visual food cues were also found to further activate the cortex and propel the desire for food. Willpower may play a role in moderating the cortex, but other medicinal interventions or optical switching of the individual brain cells might be required.
Gary Keller in his book titled One Thing, explained the fascinating way the brain works and manages our hunger. The brain makes up 1/50 of our body mass but consumes an incredible 1/5 of the calories we burn for energy.
Gary Keller pointed out that “most of our conscious activity is happening at our prefrontal cortex, the part of the brain that is responsible for focus, handing short term memory, solving problems and moderating impulse control. The last in and first out theory works in our brains too. If there is a shortage of resources to the brain such as skipping a meal, the older more developed areas of the brain, such as those that regulate breathing and our nervous responses get first helpings from our blood stream.” So in defence of the human body, the brain plays some games even within itself!
What is certain is that the mind and the brain will continue to play a pivotal role in fighting hunger, conquering obesity and resisting negative desires. Science may help in increasing food supply to satisfy hunger or in devising means to divert hunger for overweight class of people. But the battle of the stomach will remain in its natural place: inside every one of us.