If you feel like your weight fluctuates when you are stressed, this idea is not just in your head. Stress and weight gain are related, and not just because you can not maintain your typical healthy routine when you are going through such periods.
Whenever you are stressed, your body starts to struggle, causing it to release the hormone adrenaline to help you cope with the perceived threat that you feel anxious about. To accumulate energy to face this threat, the body also releases glucose, or sugar, into your bloodstream. When the adrenaline rushes and your blood sugar levels drop, the hormone cortisol is added to provide you with more energy to continue addressing the threat.
Since cortisol stimulates the release of insulin in order to maintain blood sugar levels, it can also trigger your cravings for sugar and your appetite in general. Giving in to these desires can lead to weight gain. In fact, research shows that people with higher weights tend to have an increased cortisol response to stress, says Vidhya Illuri, endocrinologist.
Cortisol can not only make you hungry, but it can also slow down your metabolism at the same time (another mechanism that will help you save energy in order to cope with everything that is happening).
Cortisol can also reduce muscle mass, according to a study in The Journal of Clinical Endocrinology & Metabolism. This decrease in muscle mass can also make weight management more difficult.
Stress can also affect the hunger hormones leptin and grehlin, which send signals to your brain that determine how hungry you feel. Basically, cortisol boosts these other hormones so you will make sure you eat enough to face the perceived "threats" again.
Some reasons that affect weight gain during this period are also: excessive consumption during a meal and then not eating for a very long time, fast food, alcohol, not consuming full meals, poor sleep, etc.
What to do:
Focus on exercise and physical activity; keep notes of your eating habits; cook healthier versions of your favorite dishes; hydrate, prioritize sleep; take care of yourself as much as you can; talk to a psychologist etc.