2023-06-18 11:02:06
Not only can obesity cause all kinds of diseases, it also changes the way the brain responds to food. In people with obesity, the brain hardly registers, if at all, that there is food in their stomach. And that doesn’t change if they lose a lot of weight.
The functioning of the brain has therefore changed forever, it appears research of the Amsterdam UMC and Yale University. “Our research shows that the brains of people who are obese go through a lasting change. This may explain why people with severe obesity often eat more than necessary,” says lead researcher Mireille Serlie. An important neurotransmitter plays a role in this. “We found that obese people produce less dopamine than healthy people in a brain region that regulates food cravings. This hormone is responsible, among other things, for the rewarding feeling that eating and drinking causes.”
Disturbed response to food
Serlie came to this conclusion after finding 58 test subjects – 28 people with a healthy weight and 30 with obesity – willing to have food delivered directly into the stomach. At the same time, the brain activity of the participants was measured with an MRI. It soon became apparent that the brain activity of the healthy people did change when their stomachs were full, while nothing happened in the specific brain area of people with serious obesity. Dopamine release in the brain, measured by means of a SPECT scan, also appeared to function worse in the obese group. “These findings indicate a reduced brain response to the presence of food in the stomach and intestines in obese people. This disrupted response can have major consequences for eating behavior and could explain why obese people continue to eat even when they are full,” Serlie explains.
Interchangeability
The processing of our food is a complex interplay of neurological signals and metabolic signals between the brain, the gastrointestinal system and receptors in the blood that measure all kinds of nutritional values. This interaction creates feelings of hunger or satiety at the right times. Researchers know a lot better how this works in animals than in humans. That is why the results of this research are so interesting: finally there is a reliable study in humans that sheds light on these processes. Particularly surprising is that the consequences of obesity appear to be irreversible.
Even a 10 percent loss of body weight after a 12-week diet program was not enough to improve dopamine release in the obese participants. So it seems strongly that long-term changes occur in the brain, lasting at least three months in obese people. “Remarkably, the responses in the brain remained the same as before the weight loss. This could contribute to the weight gain that we very often see after people have successfully lost weight first. If the brain does not change along with it, it is difficult to maintain healthy eating habits,” concludes Serlie.
Obesity, the numbers
According to the latest figures from Statistics Netherlands, half of the adult Dutch population will be overweight in 2021. These are slightly more men than women (53 versus 47 percent). 36 percent are moderately overweight, so a BMI between 25 and 30 and 14 percent are obese (a BMI over 30). Slightly more women than men are seriously overweight and low-educated people are almost twice as likely to be highly-educated. In general, obesity is most common among people over 50.
BMI
The Body Mass Index has long been the benchmark for determining whether someone has a healthy weight. Anyone with a BMI below 20 is underweight. A BMI between 20 and 25 is considered healthy. Between 25 and 30 we speak of overweight and people with a BMI of 30 or higher are obese. You can also calculate your BMI yourself. To do this, divide your weight in kilograms by the square of your height in meters. Today, however, more and more people are pointing out the dangers of belly fat. A lot of belly fat would be a better indicator of your health than your BMI. In addition, a waist circumference of less than 94 centimeters for men and less than 80 centimeters for women is considered healthy.
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