Why You Should Never Take A Bath After Eating
As it turns out, showering or bathing right after eating a meal may not good for your digestive system. That's because taking a warm shower or bath can trigger a process called hyperthermic action, which increases your body's internal temperature by a few degrees (via Healthline). This process can help boost your immune system, stimulate your sweat glands to flush out toxins, and relax your nervous system. But while hyperthermic action is normally good for you, it can disrupt your digestion if this process begins when your stomach is full.
Eating a heavy meal already raises your internal body temperature, which can increase blood flow to your digestive organs. A warm bath or shower might therefore confuse your body, stimulate hyperthermic action instead of directing blood flow to your digestive tract, causing your digestion to slow down. This may lead to stomach cramps, bloating, heartburn, and fatigue. Waiting at least 20 minutes after eating before taking a warm bath or shower is the best way to prevent this from happening.
Cold showers can boost your metabolism
While warm showers and baths may slow down digestion after eating, cold showers can have the opposite effect. Instead of elevating your body temperature or redirecting blood flow away from your digestive tract, taking a cold shower can actually speed up your metabolism and improve digestion (via Well+Good). That's because cold showers force your body to regulate its own internal temperature, which requires quite a bit of energy. When you get cold, your body involuntarily shivers to generate heat and warm you back up. This expends a decent amount of energy, burning calories in the process and giving your metabolism a boost.
"Cold is much more of a shock, [which] kicks the cardiovascular system into high gear to ramp up metabolism for the day," Dr. Jessica Krant told Shape. Limited research has also shown that cold air or water can actually activate brown fat, or healthful fat, which can speed up your metabolism and help you burn more calories.