INS and obesity due to melanocortin 4 receptor deficiency: social behavior, anxiety, COVID-19, pandemic, psychological impact, depression, mental health, comfort food, neurophysiological mechanism, intrinsic reward mechanism, hyperpalatable food, obesity, inflammation, visceral weight gain, cardiovascular, adipose tissue, complications, calories, nutrient density, hunger, insulin resistance, cancer, body mass index (BMI), intensive care unit, SARS-Cov-2