UNDER AUTOMATIC CONTROL

Stable blood glucose not your job

Too important an activity to be left to chance.

In Summary
  • If you’ve not eaten for a while, you blood glucose will drop a little.
  • Sensing this, stored glucose will be released from your liver to replenish and maintain normal glucose levels until your next meal
Regulation of blood sugar is one of the most exquisite ‘mission control’ activities in your body.
Regulation of blood sugar is one of the most exquisite ‘mission control’ activities in your body.
Image: OZONE

Many nutritionists and dieticians recommend eating several times a day, so as to keep the blood sugar ‘stable’. A leaflet from a leading hospital in Nairobi advises diabetics to eat five times a day—three main meals and snacks in-between.

We have been told that breakfast is the most important meal of the day—that we should flood our bodies with energy and nutrition as soon as we arise. You’ve been warned against leaving the house on an empty stomach; that doing so will send your blood glucose crashing down, leaving you physically weak and mentally vulnerable to overeating later.

A few weeks ago, I wrote an article dissecting our obsession with eating three times a day. A practice that has become so habitual, that we start to feel hungry just before our bodies are expecting a meal. Many of us now eat guided by the clock, rather than by true hunger signals.

Does it make sense for our bodies to demand a steady stream of dietary glucose in order to survive? If this is the case, how and why do we stay alive when we’re asleep and not eating, or when we are undertaking a prolonged fast for religious or cultural reasons?

Throughout human history, food scarcity was often a real concern. Eating three times a day, let alone five times a day was a luxury that our ancestors could not afford. Access to a reliable, steady energy supply in times of food shortage was a necessary adaptation to ensure survival.

Breathing, eating and keeping warm are essential to survival, as is the regulation of your blood sugar. You do not decide when to breathe or how fast or slow your heart beats. You cannot choose not to shiver if you feel cold. These activities that are necessary for life must be under automatic control. All the critical biochemical processes that take place inside our bodies are controlled by hormones (chemical messangers). And so is our blood sugar.

Too much or too little blood sugar can cause dangerous disease states that can ultimately lead to death. Stable blood glucose is so essential and so critical for survival that the task of regulating this steady state befalls a sophisticated control system called homeostasis.

Breathing, eating and keeping warm are essential to survival, as is the regulation of your blood sugar. You do not decide when to breathe or how fast or slow your heart beats. You cannot choose not to shiver if you feel cold. These activities that are necessary for life must be under automatic control. All the critical biochemical processes that take place inside our bodies are controlled by hormones (chemical messangers). And so is our blood sugar.

Regulation of blood sugar is one of the most exquisite ‘mission control’ activities in your body. An average-sized adult has four grammes (approximately one teaspoon) of glucose circulating in their bloodstream. This glucose is critical to ensure normal function of many types of cells.

We have lots of glucose stored in our muscles and liver. It is here for a reason and it cycles in and out of the bloodstream as is required to satisfy the nutritional need for glucose, while still maintaining stable blood glucose levels.

Stored glucose in the liver is used to constantly replenish the four  grammes of glucose circulating in the blood. To ensure the brain has an adequate supply of glucose, the liver releases glucose into the bloodstream at a rate similar to the uptake of glucose from the blood into tissues, thereby stabilising blood glucose concentration between 4.0 and 5.5 mmol/L (70–100 mg/dL). This remains true even in the absence of dietary carbohydrates, or during a prolonged fast. In these situations, when liver glucose (glycogen) levels are usually quite low, glucose can be manufactured from scratch, using non-carbohydrate sources such as fat or protein.

Here’s the truth. If you’ve not eaten for a while, you blood glucose will drop a little. Sensing this, stored glucose will be released from your liver to replenish and maintain normal glucose levels until your next meal.

The reason you feel dizzy and shaky is not because your blood glucose is too low, it’s because it is relatively low - relative to its most recent state. If you tested your blood glucose at this time, it would be lower than what it was just after your last meal. But it would still not meet the definition of hypoglycaemia (clinically low blood glucose – below 4.0 mmol/L).

This, of course, does not apply to anyone taking medication that can interfere with blood glucose control, particularly anti-diabetic medication.

The take home message is that blood sugar control is tightly regulated by biochemical and hormonal signals, and not by your dietary intake. Such an important activity could not just be left to chance.

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