Chronic stress, immune imbalance, and thyroid dysfunction are deeply interconnected. This forms a stress–immune–thyroid triad where each system influences the others, affecting energy, mood, and resilience. Research shows that targeted support—including adaptogens, micronutrients can help restore communication across this network. Rather than offering quick fixes, this systems-based approach addresses underlying feedback loops, combining clinical insight, patient engagement, and supportive lifestyle practices to rebuild physiological balance and improve well-being over time.
Laura Lewis, MS
Not all mood swings are related to blood sugar fluctuations, but most blood sugar fluctuations will have an effect on your mood. So, whether you have a chronic mood issue or just a shifting, negative mood, it may be worth considering your nutrition and eating habits. Glucose imbalance could be at the root of your problem.
What is the relationship between blood sugar and mood swings?
The most basic relationship between sugar and mood is the fact that the brain runs almost purely on glucose.
When blood sugar is out of balance, either too high or too low, it can cause negative changes to mood. This is a secondary effect of brain cells shifting from normal function. Classically, too-high blood sugar presents as anger or sadness, while low blood sugar (hypoglycemia) presents as nervousness or anxious feelings, but these emotions are not exclusive to either end of the blood sugar spectrum. [1]
Those with metabolic diagnoses are significantly more likely to also be diagnosed with a mood issue. [2,3] In fact, nearly 70% of examined patients with blood sugar imbalance in one particular study reported depressed feelings, 46.2% reported uncontrolled emotional reactions, 44.7% had constant internal tension, 56.2% reported sleep-wake cycle disorders, and 90% reported fatigue. [2] It is highly likely that mood challenges and metabolic issues are connected due to the complex relationship between glucose and the brain.
While blood sugar dysregulation is typically associated with specific metabolic diagnoses, mood swings can be caused by significant shifts in blood sugar in metabolically healthy individuals too. [3] Therefore, the information presented in this article is valuable for otherwise-healthy individuals and those struggling with metabolic challenges.
High Blood Sugar vs. A Blood Sugar Spike
A “sugar rush” after you eat something sweet or heavy in simple carbohydrates is different from having “high blood sugar”. When we eat foods that are high in sugar, (low in fat, fiber, and protein) there is very little work for the digestive system to do before all of the meal’s glucose is available in the blood, all at once.
If we are metabolically healthy, a sugar rush follows a spike in blood sugar. The pancreas releases an appropriate level of insulin, and our cells take up the glucose from the blood. Blood sugar levels quickly return to the normal range after a spike.
With so much glucose taken up at once, our cells have extra substrate for ATP (cellular energy) production, and we may feel a brief boost in physical energy and a brief boost in our mood. If we don’t eat more for a period of time, however, glucose availability is quickly back to 0. That spike in sugar and energy is likely to be followed by a crash: low energy and low mood.
High blood sugar that stays high (hyperglycemia) is a serious health threat. It is most likely to happen when body cells have become “insulin resistant” or stop responding to the insulin’s signal that glucose is available for pickup from the bloodstream.
Although “high blood sugar” sounds like it would cause an abundance of energy, it is more likely to feel like fatigue. Blood glucose is high because cells are not absorbing the glucose available. In cases of insulin resistance, all that extra sugar in the blood stays in circulation, crosses the blood-brain barrier, and can cause damage to the brain. [4]
Low Blood Sugar and Mood
The fact that the term “hangry” exists, is evidence that many of us can relate to low blood sugar affecting our mood. However, blood sugar below the normal range and hunger are not the same.
Because glucose is the preferred substrate for cellular energy production, when levels in the blood are low, we are likely to feel low physically. Because the brain requires glucose to function, the body has multiple systems in place to keep blood glucose within a normal range, even between meals.
An empty stomach triggers the release of a hormone called ghrelin, which in turn causes familiar hunger pangs. One of ghrelin’s roles is to signal the release of any glucose stored in the liver or muscles and activate gluconeogenesis (the production of glucose from amino acids) to provide your brain with some blood sugar, even when you are in a fasting state. Ghrelin’s other job is to signal your brain to feel “hungry” and start salivating in preparation for a meal.
Listen to those signals!
If you do not eat in response to hunger signals (like when you are dieting, fasting, or haven’t been to the grocery store), your body not only releases stored glucose, it also signals to the adrenal glands to release stress hormones. Your body is now entering physiological starvation mode, which is a stress state. In response to cortisol and adrenaline, you may start to feel shaky and irritable (hence the term “hangry”).
If you are metabolically healthy, and you eat when you are hungry, your brain and body will get a slow and steady stream of glucose. This pattern pulls your mood and energy levels back on track.
For those who are not metabolically healthy, low blood sugar can cause a variety of symptoms beyond mood and energy swings. Low blood sugar may feel like “hanger”, but it can also make you feel sweaty, light-headed, confused, or tingly. [5] In extreme cases, hypoglycemia can lead to loss of consciousness and other serious issues. [5]
How can I prevent blood sugar-related mood swings?
When we eat a high-sugar meal (or a savory one that is rich in simple carbohydrates), glucose floods the circulation. This can trigger an exaggerated insulin response that quickly turns into acute, reactive hypoglycemia. [3] Cells take up a high level of glucose quickly in response to the high-insulin signal, but without a follow-up supply, they suddenly shut down activity. When you hear of a “sugar rush” followed by a “crash” in energy and mood, this is the biological reason.
Alternatively, we can eat meals that contain a balance of fiber, fat, and protein. In a healthy balanced meal, simple carbohydrates still provide a little bit of glucose available immediately in the bloodstream. It is followed by slow and steady glucose availability as the slower-to-digest macromolecules move through the digestive system. There is no rush and crash, just a steady stream of available glucose to be absorbed throughout the body and brain.
If you notice that your mood and energy levels are sensitive to changes in your blood sugar after eating (or not eating), you may want to talk to your healthcare practitioner about potential metabolic conditions. If you are metabolically healthy, and sensitive to blood sugar changes, try carrying healthy snacks. Avoid sugar and simple carbs and eat every two to three hours to maintain balanced blood sugar. Although this strategy has been debated and some practitioners advise against its long-term use.
It sounds counter-intuitive, but many people with chaotic blood sugar levels have had success achieving healthier balance with intermittent fasting.
Disclaimer:
The information provided is for educational purposes only. Consult your physician or healthcare practitioner if you have specific questions before instituting any changes in your daily lifestyle including changes in diet, exercise, and supplement use.
Laura Lewis is a clinical researcher and science communicator with a Master of Science degree and a background in nutrition science and integrative health. She brings a decade of experience translating complex clinical data into accessible insights for healthcare practitioners and patients alike.
Laura has contributed to educational programming and strategic content development across the integrative and functional medicine space. Her strengths lie in evidence synthesis, practitioner engagement, and crafting communications that bridge the gap between scientific rigor and real-world application. At ARG, Laura supports clinical content development and educational initiatives that elevate practitioner confidence and product credibility.