The brain requires a continuous supply of fuel to perform, even during sleep.
Any imbalance in the supply of glucose to the brain and you can experience fatigue, irritability, dizziness, insomnia, poor concentration, and forgetfulness, amongst other symptoms. If you tend to get "hangry" in between meals and feel the need to snack on carbs, you may be riding the blood-sugar roller coaster.
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The body works hard to maintain the level of blood glucose within a narrow range (between 70 mg/dl and 110 mg/dl.), and this is achieved mainly by two hormones: insulin and glucagon.
When there is an increase of glucose in the blood, for example after meals or under stress (yes, cortisol raises glucose!), insulin helps transport glucose from the blood into muscle, red blood cells and fat cells.
If blood glucose drops, glucagon is secreted, causing the liver to convert stored glycogen into glucose (glycogenolysis or fatty acid break-down), or to manufacture glucose from protein or triglycerides (gluconeogenesis), and release it to the bloodstream. Except, of course, if you succumb to the infamous snack attack. Which causes yet another spike in glucose, and the cycle continues.
These highs and lows create stress and inflammation.
Mood swings, depression, hormonal imbalance and weight gain are the short term results of the the sugar roller coaster. In the medium term, the body may become insulin resistant and which could eventually lead to diabetes, when the pancreas can't keep up and finally stops producing insulin.
Probably half of the people I see in my practice tell me they need to eat something (typically sugary or starchy) in regular intervals or else they get "hangry". But grazing throughout the day, particularly on processed or refined carbohydrates, will only exacerbate the effects of the sugar roller coaster.
Our ancestors did not have access to food 24/7 as we do now. Intermittent fasting is becoming popular not only because it can help lose weight and reduce the risk of chronic diseases - thanks to robust changes in energy metabolism characterized by increased insulin sensitivity, reduced levels of insulin and leptin, mobilization of fatty acids, and elevation of ketone levels -, but it can also lead to better sleep and increased energy. (Mattson, et al., 2014) All of the protocols for intermittent fasting emphasize the importance of the nutritional quality of the meals that are consumed and advocate drinking plenty of water, both to stay hydrated and to alleviate hunger. One of easiest protocols advocates having only 2-3 meals daily within a window of eight hours, avoiding food for at least three hours before bedtime. Although intermittent fasting might sound too dramatic and hard to follow for some and almost impossible to endorse in a work environment, there are some salient aspects in relation to resilience and performance.
A meal consumed close to bedtime is indeed associated with sleep disturbances, with the consequent impact on the circadian rhythm and the adrenal glands.
A longer window of overnight fasting allows the digestive system to rest and restore, thus improving its function.
The claim that fewer intakes of food can help modulate glucose and insulin levels, with the consequent positive impact on cortisol (released upon hypoglycemia), is also promising for helping achieve a sustained brain energy supply.
In summary, a good strategy to get off the blood-sugar roller coaster involves:
Staying away from refined carbs and sugars.
Choosing low glycaemic carbs, combined with good sources of protein and fats.
Avoiding snacking. Go for at least a 12-14h window of overnight fasting coupled with 2-3 squared meals.