Sugar is often associated with instant “whiplash” effect. We consume it and, a few minutes later, we feel full of energy. But this effect is misleading: after this rapid peak, our body often experiences an equally rapid fall. Result : fatigue, cravings irritability, difficulty concentrating…Is it just an impression or a biological reality? We take stock with Nathalie Somville, dietitian nutritionist.
Does eating sugar really make you tired?
Yes, sugar can cause fatigue spikes. But it all depends the type of sugar and how it is consumedexplains Nathalie Somville, dietitian.
In everyday language, we often speak of “sugar” in a general way. In reality, there are several types of sugars:
- Simple sugars : white sugar, honey, jam, candies, sodas, etc. They are quickly absorbed by the body, which causes rapid rise of blood sugarfollowed by an often sudden fall. This variation can give a feeling of fatigue, even drowsiness, indicates the dietitian.
- Complex carbohydrates : found in wholemeal bread, pasta, rice, whole grains, etc. They are digested more slowly and provide lasting energy. Blood sugar remains stableand post-meal fatigue is less common.
Why am I tired when I eat sugar?
“As noted above, simple sugar raises blood sugar quickly. In response, the body releases insulin to get this sugar into the cells,” explains Nathalie Somville, dietitian.
This mechanism is completely normal. But with the refined sugarslike white sugar, candies or industrial pastries, the reaction is often too fast and too strong. The result:
- THE blood sugar rises suddenlyinducing an immediate energy peak.
- L’insulin acts excessively to regulate this rise.
- THE sugar level drops quicklysometimes even below the starting level.
It is this sudden fall which causes the sensation of fatiguedrowsiness or “feeling” after a meal or snack.
How to recognize a “slump” after a sugary snack?
The sudden drop in blood sugar results in several symptoms:
- A sudden fatigueOr the desire to sit down immediately,
- Of the difficulty concentratinga feeling of empty head,
- A feeling of weakness or slightly heavy legs,
- A irritability or mood swings,
- A sweet craving which pushes us to quickly return to a sweet food.
“Our brain depends on glucose to function. When it suddenly runs out, it sends a warning signal », explains Nathalie Somville, dietician.
Are all sugars responsible for the crash?
No. As stated above, it all depends the type of sugar and the food that contains it. Some sugars can cause an energy spike followed by a rapid drop, while others provide more stable, long-lasting energy.
The sugars that make you most tired
You will have understood, these are fast sugarsoften found in processed foods. They are absorbed very quickly by the body, which causes a spike in blood sugar followed by a feeling of fatigue, sometimes a few hours later. They are found in:
- THE ultra-processed products (prepared meals, industrial sauces, etc.),
- THE sodas and other sugary drinks,
- THE sweets and pastries,
- THE refined cereals (cornflakes, white rice, etc.),
- THE pastries (croissants, pain au chocolat, etc.).
“These foods are poor in fibers and in proteins. Sugar is absorbed too quickly,” explains Nathalie Somville, dietician. Result: a downturn which can occur quickly after consumption.
Sugars that give more lasting energy
Some sugars are absorbed more slowly thanks to the fiber and nutrients that accompany them. They provide stable energy and prevent fatigue. They are found in:
- THE whole fruit (apple, pear, citrus fruits, etc.),
- THE legumes (lentils, chickpeas, beans, etc.),
- THE whole grains (oats, whole grain rice, whole grain pasta, etc.).
These foods slow the absorption of sugar and stabilize blood sugar levels. Energy is released gradually, helping you stay focused and alert.
Should you completely eliminate sugar from your diet?
No. The goal is not to ban sugar, but to consume it better. Sugar is part of food and provides energy to the body. Removing it completely is neither necessary nor pleasant in the long run.
How to avoid the energy drop linked to sugar?
To limit fatigue after consuming sugar and maintain your energy, a few simple habits are enough.
- Favor natural sugars : whole fruits, legumes, whole grains. They provide energy gradually and avoid blood sugar peaks.
- Never consume sugar alone : always combine it with proteins (yogurt, cheese, eggs), fiber (fruits, vegetables, whole grains) or good fats (almonds, nuts, seeds). These associations slow down the absorption of sugar and prolong the feeling of energy.
- Avoid sugary drinks and ultra-processed foods : sodas, sweets, pastries cause rapid rises in sugar followed by sudden drops.
- Split your meals and snacks : prefer several small, balanced snacks during the day rather than a large sugary dessert after a meal. For example: fruit with a few almonds, or natural yogurt with oatmeal.
- Eat at regular times : Skipping a meal increases cravings and fatigue, warns Nathalie Somville.
- Hydrate regularly : dehydration accentuates the feeling of fatigue!
- Listen to your body : recurring fatigue, drowsiness after meals or sugar cravings are signals that should not be ignored.
Bottom line: sugar can give you a boost, but can also cause a rapid drop in energy. By favoring good sugars, by eating balanced and regularly, you keep stable energy all day long.