Sugar: an underestimated source of fatigue

can't stop sugar - comic

Everybody is scared of the shark. And still, the oyster kill more people per year than the shark. In food, it’s the same. Everybody cares about cholesterol, but the body needs sugar. Right?

This content is a follow up on the article on glycemia and insuline. If you don’t know what those are, I invite you to read it.

Note: what I call sugar here actually include all carbs. They all increase sugar blood level.

The myth of sugar as a necessary source of energy for the body

Many people believe that the body, and specially the brain, works using the sugar that we intake. That is true. But what they usually ignore, is that it is not necessary at all.

Actually, the body doesn’t need to be fed with sugar to work properly. It knows how to synthesize the energies that it requires. I drew the mechanism for the skeptics:

fat to fuel - scheme

Muscles can get their energy from glucose, but also from fatty acids. The brain can get its energy from glucose, but also from ketone bodies.

So what’s the problem with sugar rich food?

When it works properly, the body manages to maintain an approximately steady glycemic level (sugar blood level). This correspond to a teaspoon of sugar into 5 liters of blood. When you compare that with the amount of sugar that some people intake, you cannot but realize how little it is.

glycemia homeostasis - scheme
Homeostasis : the blood glucose level is keep steady

During a normal meal, the blood sugar level goes a little bit over the tolerance level. The pancreas then release insuline in order to lower that level.

For the record, insuline is the hormone that, among others, enables the glucose to be consumed by the muscles or the organs. That consumption of glucose lowers the level.

Glycemia and insulin of a normal meal - scheme
Normal meal: insuline regulates the excess of sugar blood by triggering glucose consumption

During a rich meal, the blood sugar level will spike. Since it can become dangerous for the body, the pancreas kind of panic and release an excess of insuline. To be sure. This reaction triggers a transition from hyperglycemia to hypoglycemia.

Glycemia of a heavy meal
A heavy meal will trigger hyperglycemia. The insuline spike that follows will then trigger hypoglycemia.

When undergoing hypoglycemia, the body is gonna ask for more sugar. If you go for it, the sugar roller-coaster is gonna go for another ride…


All those glycemia changes will trigger body disruptions. Here is the list of the major symptoms.


  • Tired eyes
  • Need a nap
  • Brain fog


  • Anxiety
  • Depression
  • Moody
  • Irritable
  • Sugar cravings

And that’s without taking into account the long term effects, that are more complex.

sugar fucked up - comic

Food glycemic index

The glycemic index indicates how fast will the sugar from food be absorbed and released into the blood. So, the higher the glycemic index, the more it will trigger glucose and insuline spikes. Which is exactly what we want to avoid.

If you search on google, it’s quite easy to find a list of the glycemic indexes for all kinds of food. What you need to remember is the highest glycemic indexes: beer, syrup, sodas, fruit juices, sweets, white flours (bread), cakes, pastries…

What can you do?

If you want to exit that pattern, you need to change your habits. If you drink sodas or fruit juices, you might want to start there, it’s the easiest. Same for alcohol, obviously. Reduce your white bread consumption as much as you can. Then you can also avoid sweet desserts (or replace them by an unsweetened yogurt). Also avoid hidden sugars. when you by already made food, there is always sugar somewhere. Same for the sauces (from tomato sauce to dressings, all of them…), soups, cereals (that are already carbs)… the list a damn long. Buy vegetables and cook yourself. Your body will be grateful. The very minimum is to read the labels of the products you buy.

All the efforts I just mentioned are a good first step against fatigue. With time, your habits can evolve and it will feel completely natural at some point. But changing your habits is often something difficult, so don’t put too much pressure on it. Just go slow, one step at a time. Do what you can, not more. It would be a shame if you give up because of too much ambition. Be proud of each step and congratulate yourself. It’s not an easy road.

What is the sweet food or drink that you can’t get rid of? Leave a message in the comments.

Partagez si vous aimez !

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.