The Glucose–Mood Axis
The brain depends on a continuous glucose supply, yet it cannot store glucose itself. Maintaining consistent blood sugar regulation is essential for regulating emotions, preventing mood swings, and cognitive performance. Blood sugar fluctuations – hyperglycemia followed by reactive hypoglycemia – can mimic or exacerbate psychiatric symptoms.

Symptoms of dysglycemia include:
- Anxiety, restlessness, or panic
- Irritability or anger outbursts
- Fatigue and brain fog
- Cravings for sugar or stimulants
- Sleep disturbances and morning headaches
Chronic glycemic instability contributes to oxidative stress, HPA axis dysregulation, and alterations in neurotransmitter synthesis – particularly serotonin and dopamine. Most Americans consume far too many carbohydrates and not enough necessary fat and dietary cholesterol. On average, most Americans are consuming about 225-300 grams of carbohydrates, making it very difficult for the rest of the body to keep up with the high demand, especially the pancreas, where insulin is produced. An overabundance of carbohydrates can create dysglycemia, which impacts the brain and leads to mental health and neurological concerns.
Insulin Resistance and Depression
Insulin resistance, a hallmark of metabolic dysfunction, reduces glucose transport into neurons, leading to “energy starvation” of the brain. Research indicates a strong bidirectional relationship between depression and insulin resistance (Gruber et al., 2023). Inflammatory cytokines, such as TNF-α and IL-6, further impair insulin signaling, thereby perpetuating neuroinflammation.
Individuals with metabolic syndrome often exhibit hippocampal atrophy, decreased brain-derived neurotrophic factor (BDNF), and poor stress tolerance – factors that increase vulnerability to mood disorders.
Cortisol, Stress, and Blood Sugar
Cortisol acts as a glucocorticoid hormone that mobilizes glucose during stress. Short-term activation is adaptive; however, chronic cortisol elevation from prolonged stress or poor sleep drives muscle catabolism, insulin resistance, and visceral fat deposition.
High cortisol simultaneously suppresses serotonin synthesis and impairs GABA signaling, heightening anxiety and mood instability. Nutritional strategies that stabilize blood sugar – such as regular balanced meals and complex carbohydrates – help regulate cortisol rhythms.
Chronic cortisol elevation from prolonged stress dysregulates the hypothalamic–pituitary–adrenal (HPA) axis, impairing the brain’s ability to maintain balance between stress and recovery. Persistently high cortisol levels damage neurons in the hippocampus, reducing memory and emotional regulation, while simultaneously enhancing activity in the amygdala, which heightens fear and anxiety responses. This imbalance leads to sleep disruption, blood sugar instability, and neurotransmitter depletion – particularly of serotonin, dopamine, and GABA – all of which are crucial for mood stability (Hersey et al., 2022). Over time, these physiological changes contribute to depression, anxiety, irritability, and cognitive decline, reinforcing a cycle of chronic stress and mental health vulnerability.
The adrenal glands are designed to maintain high cortisol levels only for brief periods. Once we have exhausted that capacity, the cortisol levels start to fall. This dramatic reduction in cortisol can also leave us feeling apathetic and having low energy, brain fog, and anxiety/depression symptoms.
The Role of Reactive Hypoglycemia
Reactive hypoglycemia occurs 2–4 hours post-meal and results from excessive insulin release. Symptoms can mimic anxiety attacks due to catecholamine release. Clinically, these clients often benefit from:
- Eating balanced meals every 4-5 hours. (This gives the digestive tract enough time between meals and time for leptin/ghrelin and insulin to reset to base level as it should.)
- Including protein and healthy fats at each meal.
- Limiting refined carbohydrates and caffeine.
- Supporting adrenal health with B vitamins, magnesium, and adaptogenic herbs.
Ketones and Cognitive Clarity
For some individuals, mild nutritional ketosis – achieved through lower-carbohydrate, higher-fat diets – can stabilize mood and enhance focus by providing ketones (β-hydroxybutyrate) as an alternative brain fuel (Borrego Ruiz & Borrego, 2025). Ketones exhibit neuroprotective and anti-inflammatory effects and increase mitochondrial efficiency. However, ketogenic interventions should be personalized, particularly in individuals with adrenal exhaustion or eating disorder histories.
The above is a course excerpt from Nutritional Psychology: Bridging Brain, Body, and Behavior, a 2-hour online continuing education (CE/CEU) course that explores the relationship between food and mood, and how lifestyle factors influence mental health outcomes.
Professional Development Resources, a small Florida nonprofit educational corporation 501(c)(3) organized in 1992, is approved by the American Psychological Association (APA) to sponsor continuing education for psychologists. Professional Development Resources maintains responsibility for all programs and content. Professional Development Resources is also approved by the National Board of Certified Counselors (NBCC ACEP #5590); the Association of Social Work Boards (ASWB #1046, ACE Program); the Continuing Education Board of the American Speech-Language-Hearing Association (ASHA #AAUM); the American Occupational Therapy Association (AOTA #3159); the Commission on Dietetic Registration (CDR Prior Approval Program); the Florida Board of Clinical Social Work, Marriage & Family Therapy, and Mental Health Counseling, Board of Psychology, Office of School Psychology, Board of Speech-Language Pathology & Audiology, Board of Occupational Therapy, and Dietetics and Nutrition Practice Council; the New York State Education Department’s State Board for Psychology as an approved provider of continuing education for licensed psychologists (#PSY-0145), State Board for Mental Health Practitioners as an approved provider of continuing education for licensed mental health counselors (#MHC-0135) and marriage and family therapists (#MFT-0100), and the State Board for Social Workers as an approved provider of continuing education for licensed social workers (#SW-0664); the South Carolina Board of Professional Counselors and Marriage & Family Therapists (#193); the Texas Board of Examiners of Marriage and Family Therapists (#114) and State Board of Social Worker Examiners (#5678); and is CE Broker compliant (#50-1635 – completions are reported next business day, currently reporting for 50+ boards). Learn more about us.
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