By Lina Begdache, assistant professor of nutrition, Binghamton University, State University of New York
If you experienced unwanted weight gain or loss during the pandemic, you are not alone. According to a survey by the American Psychological Association, 61% of American adults reported unwanted weight changes since the pandemic began.
The results, released in March 2021, showed that during the pandemic, 42% of respondents gained unwanted weight – 29 pounds on average – and almost 10% of those people gained more than 50 pounds. On the other hand, almost 18% of Americans said they experienced unwanted weight loss – on average, a loss of 26 pounds.
Another study, published on March 22, 2021, assessed weight change in 269 people from February to June 2020. Researchers found, on average, that people gained 1.5 pounds a month.
I am a nutritional neuroscientist and my research investigates the relationship between diet, lifestyle, stress and mental anguish, such as anxiety and depression.
The common denominator for changes in body weight, especially during a pandemic, is stress. Another survey by the American Psychological Association in January 2021 found that about 84% of American adults experienced at least one emotion associated with prolonged stress in the previous two weeks.
Findings about unwanted weight changes make sense in a stressful world, especially in the context of the body’s response to stress, better known as a fight or flight response.
Fight, flight and food
The fight or flight response is an innate reaction that has evolved as a survival mechanism. It enables humans to react quickly to acute stress – like a predator – or to adapt to chronic stress – such as food shortages. When faced with stress, the body wants to keep the brain alert. It lowers the levels of some hormones and brain chemicals to reject behaviors that will not help in an urgent situation and increases other hormones that do.
When under stress, the body reduces levels of neurotransmitters such as serotonin, dopamine and melatonin. Serotonin regulates emotions, appetite and digestion. Therefore, low levels of serotonin increase anxiety and can change a person’s eating habits. Dopamine – another wellness neurotransmitter – regulates goal-oriented motivation. Decreasing levels of dopamine can translate into less motivation to exercise, maintain a healthy lifestyle or perform daily tasks. When people are under stress, they also produce less of the sleep hormone melatonin, causing trouble sleeping.
Epinephrine and norepinephrine mediate the physiological changes associated with stress and are elevated in stressful situations. These biochemical changes can cause mood swings, affect a person’s eating habits, reduce goal-oriented motivation and disrupt a person’s circadian rhythm.
Overall, stress can unbalance your eating habits and motivation to exercise or eat healthily, and this past year has certainly been stressful for everyone.
Easy calories, low motivation
In both studies, people reported their weight and the researchers did not collect any information about physical activity. But, one can cautiously assume that most of the weight changes were due to people’s gain or loss of body fat.
So, why did people gain or lose weight in the past year? And what explains the dramatic differences?
Many people find comfort in high-calorie foods. That’s because chocolate and other sweets can make you happy by increasing serotonin levels in the short term. However, the blood clears the extra sugar very quickly, so the mental stimulus is extremely short-lived, causing people to eat more. Eating for comfort can be a natural response to stress, but when combined with less motivation for exercise and consumption of foods low in calories and nutrients, stress can result in unwanted weight gain.
What about weight loss? In short, the brain is connected to the intestine through 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 that happens, people experience fullness.
The pandemic left many people confined to their homes, bored and with too much food and little to distract them. By adding the stress factor to this scenario, you have a perfect situation for unwanted weight changes. Stress will always be a part of life, but there are things you can do – like engaging in positive self-talk – that can help you avoid the stress response and some of its unwanted consequences.