There is a spectrum between eating while stressed, eating for comfort, and of course, compulsive and disordered eating. Binge eating and emotional eating are two different things, and it is important not to confuse the two. With social media today, the term binge eating, especially during self-quarantine, is thrown around loosely. In my academic career, I studied and researched extensively different impulse control and eating disorders related to binge eating, so I understand how these times can be triggering for someone who suffers from this behavior. That's why it is important to separate it from emotional and stress eating.
Neurochemically, there are multiple hunger-related signaling factors in the hypothalamus that trigger a hunger response and a satiety response. These include leptin, serotonin, dopamine , and norepinephrine. Dysregulation in these chemicals can lead to eating past fullness. Similarly, people who are overly rewarded by dopamine tend to overeat and in general eating sugary, carb-filled food tends to be a dopamine-releasing experience. People who frequently overeat tend to become more reward-sensitive in the brain.
Developmentally, two things can trigger overeating; in utero an extreme calorie deprivation has a correlation with people who overeat when they are older. Growing up in a family where food is always used as a reward, or a punishment (i.e., going to bed without dinner) can cause safety behaviors with food later on, such as overeating. Growing up in a family that eats as a form of comfort promotes it as a learned behavior to you as well. As adults, people are often socialized to have "comfort" foods which can lead to stress and emotional eating behaviors as it is normalized.
However, the most commonly recognized theory on why we emotionally eat and stress eat is that during high points of stress (emotional arousal) people become insensitive to their own hunger and satiety cues. This can even mean you may confuse your own emotional signals of stress with hunger, which can lead to overeating. A combination of a predisposition to overeating and a habit of overeating during stressful times can lead to emotional eating.
It is important during these times of uncertainty to be kind to yourself. If you stress about how much you are eating you will only worsen the cycle. If you overeat one day, remember that it's just one day and you can go back to what feels best for your body the next day. Eat when you feel hungry, and don't worry about whether it is stress or worry driving it. There are consequences to what you eat, but they shouldn't dictate your entire life. Eat to live, don't live to eat.
Tan, C. C., & Chow, C. M. (2014). Stress and emotional eating: The mediating role of eating dysregulation. Personality and Individual Differences, 66, 1-4.
Turton, R., Chami, R., & Treasure, J. (2017). Emotional eating, binge eating and animal models of binge-type eating disorders. Current obesity reports, 6(2), 217-228.
Blumenthal, D. M., & Gold, M. S. (2010). Neurobiology of food addiction. Current Opinion in Clinical Nutrition & Metabolic Care, 13(4), 359-365.
Michopoulos, V., Powers, A., Moore, C., Villarreal, S., Ressler, K. J., & Bradley, B. (2015). The mediating role of emotion dysregulation and depression on the relationship between childhood trauma exposure and emotional eating. Appetite, 91, 129-136.
Francis, L. A., & Birch, L. L. (2005). Maternal influences on daughters' restrained eating behavior. Health Psychology, 24(6), 548.