Final answer:
Sleep deprivation can cause obesity due to a surge in appetite from hormonal impairment, specifically, reduced leptin and increased ghrelin levels that lead to overeating and reduced physical activity.
Step-by-step explanation:
One reason why sleep deprivation can lead to obesity is the surge in appetite due to impairment of hormones. Lack of sleep affects the regulation of appetite-controlling hormones like leptin and ghrelin. Leptin is the hormone that signals satiety and suppresses appetite, while ghrelin increases hunger. When you are sleep deprived, your body experiences a drop in leptin levels and an elevation in ghrelin levels, which lead to increased hunger and appetite. This hormonal imbalance can result in overeating, which ultimately contributes to weight gain and obesity.
Moreover, a lack of sleep can lead to fatigue, making it more difficult for individuals to engage in physical activity, which is necessary for maintaining a healthy weight. The combination of increased caloric intake due to a greater appetite and a reduction in energy expenditure from less physical activity creates a situation conducive to weight gain.