Can obesity and stress influence your appetite? New study shows it’s all in your head
[Dec 1, 2022: Marisol Martinez, Johns Hopkins Medicine]
Researchers found that stress impacts the brain’s responses to food, and that both lean and obese adults react to food cues in areas of the brain. (CREDIT: Creative Commons)
In a series of experiments using functional magnetic resonance imaging (fMRI) to measure brain activity across networks in the brain, Johns Hopkins Medicine researchers looked at how stress might increase appetite in obese and lean adults.
The researchers found that stress impacts the brain’s responses to food, and that both lean and obese adults react to food cues in areas of the brain associated with reward and cognitive control.
The findings of the study were published in PLOS ONE.
For the study, the researchers analyzed data from 29 adults (16 women and 13 men), 17 of whom had obesity and 12 of whom were lean. Participants completed two fMRI scans, one following a combined social and physiological stress test.
Participants were given a food word reactivity test during both scans. This test involved looking at how people’s brains reacted to food words, such as menu items on a chalkboard.
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To maximize the appetitive response in the brain, the researchers asked participants to imagine how each food looked, smelled and tasted, and how it would feel to eat it at that moment. They were also asked how much they wanted each food, and if they felt they should not eat that food, to see how they approached decision-making related to each food.
“The experiments showed that obese and lean adults differ somewhat in their brain responses, with obese adults showing less activation of cognitive control regions to food words, especially to high-calorie foods, like for example, grilled cheese,” says lead researcher Susan Carnell, Ph.D., associate professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine.
The study also showed that stress impacts brain responses to food. For example, obese individuals showed greater activation of the orbitofrontal cortex, a brain reward region, after the stress test.
“We also found evidence for links between the subjective stress experienced and brain responses in both groups. For example, lean individuals who reported higher stress following the test showed lower activation of the dorsolateral prefrontal cortex, a key brain area for cognitive control,” says Carnell.
What is stress?
According to the Cleveland Clinic, stress is a normal human reaction that happens to everyone. In fact, the human body is designed to experience stress and react to it. When you experience changes or challenges (stressors), your body produces physical and mental responses. That’s stress.
Stress responses help your body adjust to new situations. Stress can be positive, keeping us alert, motivated and ready to avoid danger. For example, if you have an important test coming up, a stress response might help your body work harder and stay awake longer. But stress becomes a problem when stressors continue without relief or periods of relaxation.
What happens to the body during stress?
The body’s autonomic nervous system controls your heart rate, breathing, vision changes and more. Its built-in stress response, the “fight-or-flight response,” helps the body face stressful situations.
When a person has long-term (chronic) stress, continued activation of the stress response causes wear and tear on the body. Physical, emotional and behavioral symptoms develop.
Physical symptoms of stress include:
Aches and pains.
Chest pain or a feeling like your heart is racing.
Exhaustion or trouble sleeping.
Headaches, dizziness or shaking.
High blood pressure.
Muscle tension or jaw clenching.
Stomach or digestive problems.
Trouble having sex.
Weak immune system.
Stress can lead to emotional and mental symptoms like:
Anxiety or irritability.
Often, people with chronic stress try to manage it with unhealthy behaviors, including:
Drinking alcohol too much or too often.
Overeating or developing an eating disorder.
Participating compulsively in sex, shopping or internet browsing.
What are some strategies for stress relief?
You can’t avoid stress, but you can stop it from becoming overwhelming by practicing some daily strategies:
Exercise when you feel symptoms of stress coming on. Even a short walk can boost your mood.
At the end of each day, take a moment to think about what you’ve accomplished — not what you didn’t get done.
Set goals for your day, week and month. Narrowing your view will help you feel more in control of the moment and long-term tasks.
Consider talking to a therapist or your healthcare provider about your worries.
What are some ways to prevent stress?
Many daily strategies can help you keep stress at bay:
Try relaxation activities, such as meditation, yoga, tai chi, breathing exercises and muscle relaxation. Programs are available online, in smartphone apps, and at many gyms and community centers.
Take good care of your body each day. Eating right, exercising and getting enough sleep help your body handle stress much better.
Stay positive and practice gratitude, acknowledging the good parts of your day or life.
Accept that you can’t control everything. Find ways to let go of worry about situations you cannot change.
Learn to say “no” to additional responsibilities when you are too busy or stressed.
Stay connected with people who keep you calm, make you happy, provide emotional support and help you with practical things. A friend, family member or neighbor can become a good listener or share responsibilities so that stress doesn’t become overwhelming.
Stress is a normal reaction the body has when changes occur, resulting in physical, emotional and intellectual responses. Stress management training can help you deal with changes in a healthier way.
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Note: Materials provided above by Johns Hopkins Medicine. Content may be edited for style and length.
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