By Lina Begdache, Assistant Professor of Nutrition, Binghamton University, New York State University
If you have experienced unwanted weight gain or weight loss during the pandemic, you are not alone. According to a poll by the American Psychological Association, 61% of American adults have reported unwanted weight change since the pandemic began.
The results, released in March 2021, showed that 42% of respondents gained unwanted weight during the pandemic – averaging 29 pounds – and nearly 10% of people gained more than 50 pounds. On the other hand, nearly 18% of Americans said they experience unwanted weight loss – an average of 26 pounds.
Another study, published on March 22, 2021, assessed the weight change of 269 people from February to June 2020. The researchers found that people gained an average of 1.5 kilograms per month.
I am a nutritional neuroscientist, and my research explores the link between diet, lifestyle, stress and mental distress such as anxiety and depression.
The common denominator for changes in body weight, especially during a pandemic, is stress. In another survey conducted by the American Psychological Association in January 2021, it was found that approximately 84% of American adults experience at least one emotion related to prolonged stress during the preceding two weeks.
The findings about unwanted weight changes make sense in a stressful world, especially in the context of the body’s stress response, better known as the fight-or-flight response.
Fight, flight and food
The fight-or-flight response is an innate response that has evolved as a survival mechanism. It empowers people to respond quickly to acute stress – such as a predator – or to adapt to chronic stress – such as a food shortage. When the body encounters, the body wants to keep the brain alert. It lowers the levels of some hormones and brain chemicals to turn off behaviors that will not help in an urgent situation, and it raises other hormones that will.
When under stress, the body lowers the neurotransmitters such as serotonin, dopamine and melatonin. Serotonin regulates emotions, appetite and digestion. Thus, low levels of serotonin increase anxiety and can change a person’s eating habits. Dopamine – another neurotransmitter that feels good – regulates purposeful motivation. Decreasing levels of dopamine can translate into lower motivation to exercise, maintain a healthy lifestyle, or perform daily tasks. When people are under stress, they also produce less sleep hormone melatonin, which leads to sleep problems.
Epinephrine and norepinephrine mediate the physiological changes associated with stress and are increased in stressful situations. These biochemical changes can cause mood swings, affect a person’s eating habits, reduce purposeful motivation, and disrupt a person’s circadian rhythm.
In general, stress can be your eating habits and motivation to exercise or keep a healthy way out of balance, and this last year has definitely been a stressful way for everyone.
Easy calories, low motivation
In both studies, people reported their own weight, and the researchers did not collect any information about physical activity. But we can cautiously assume that most of the weight changes were due to people gaining or losing body fat.
So why did people gain or lose weight last year? And what explains the dramatic differences?
Many people find comfort in high-calorie foods. This is because chocolate and other sweets can make you happy by increasing serotonin levels in the short term. However, the blood cleanses the extra sugar very quickly, and the mental boost is very short-lived, leading to people eating more. Eating for convenience can be a natural response to stress, but when combined with the lower motivation to exercise and consumption of foods with low nutritional value, calorie-dense foods, stress can lead to unwanted weight gain.
What about weight loss? In a nutshell, the brain is connected to the intestines by a two-way communication system called the vagus nerve. When you are stressed, your body inhibits the signals that travel through the vagus nerve and slows down the digestive process. When this happens, people experience fullness.
The pandemic confined many people to their homes, bored and with lots of food and little to distract them. If you add the stress factor to this scenario, you have the perfect situation for unwanted weight changes. Stress will always be a part of life, but there are things you can do, such as engaging in positive self-talk – which can help ward off the stress response and some of its unwanted consequences.