Bathwater and bodyfat

Ever draw a warm bath? Then you're ready to become a glucose expert. 

Bathtubs and glucose levels are controlled as tightly as any system in a chemical refinery. Be grateful - blood sugar chemistry is at the very core of our health. 

Your bathroom and body both hide impressive plumbing beneath the surface. The mechanism is so solid we barely notice more than the the hot and cold taps. But it takes something special to deliver a nice bath without scalding.  Our ability to provide enough energy without glucose overload? Even more striking.

Start with the basics: sensors, inputs, and hitting the set point.


Temperature: Poke a finger in the water - you'll know if it's too hot or too cold.

Blood sugar: Your body checks for both low and high glucose. Both sensors - alpha and beta cells - are inside the pancreas.

Changing the inputs

Temperature: Cool down by opening the cold tap and shutting the hot tap. Switch it up for a warmer bath.

Blood sugar: Our bodies mostly rely on the pancreas to turn the two taps. Glucose is one of the few automatic systems that doesn't even involve your brain.

  • The pancreas releases insulin. This hormone tells your muscles and liver to suck up glucose. They'll convert the sugar to something safer - fat or glycogen (a locked up form of glucose). 
  • The pancreas can also release glucagon, which signals the liver to convert glucagon back into glucose.

Adjusting to the set point

Every control system aims towards a goal by adjusting the inputs.

Temperature: Keep the bath temperature steady in the comfort range between chill and scald. Adjust the taps for toilet flushes and sisters with buckets of cold water.

Blood sugar: When glucose levels are too low, you'll faint. Too high and there's cell damage. Maintain glucose levels in the comfort range. Adjust insulin and glucagon to handle changes from eating carbs or exercising.

Advanced glucose management

Good health strategies can be found in the details of our body's glucose system. Let's go deeper to think about how to keep spikes down.

Preventing shocks

Compensating for change is terrific, but why not prevent drastic variation in the first place?

Temperature: Kids always eventually discover the "bucket of cold water" trick. My girls did, my brothers and I threw the water, and I'm certain my ancestors in caveman days had their own version.

Close the door. Trust no one.

Blood sugar: One way to avoid glucose spikes is skipping on the refined sugar. Dodge the donut and there's nothing to fight against. We're only built to pig out on sugar because it has always been rare - until the day before yesterday on the evolutionary calendar.

Smoothing out the spikes

Temperature: A larger tub with more water adds thermal mass. That extra cushion reduces temperature changes.

Blood sugar: Bigger muscles and more blood (or just water in the blood) add "glucosic mass" (I just made up that term). This softens the effect of that glass of OJ.

Steady state

Temperature: Ahh. The temperature feels nice and the bath is full. Got a rubber ducky ready and you're ready to enjoy. That is the temperature you were aiming for.

Blood sugar: There are two perfect glucose levels.

  • Your body aims for a low level while you sleep and it repairs the day's damage.
  • Sleeping glucose levels don't provide enough energy for regular activity. If you needed to suddenly sprint, you'd be out of luck. So your glucose rises when you wake up, even without eating anything.

Steady glucose involves even more systems than we touched on - we'll get to them later. The six we just covered are a useful base to start from. They also highlight how critical steady glucose is - less important systems contain fewer moving parts. Most importantly, they help explain why particular habits (sleep, low sugar, exercise) increase health and suggest other ideas.

All I'm looking for from a bath is cleanliness. My glucose goal is slightly more ambitious - keep the spikes down and bathe in the true fountain of youth.