Yes, anorexia nervosa can cause hypoglycemia, and in severe cases it can be life-threatening. Blood sugar below 70 mg/dL is considered low, and studies of hospitalized anorexia patients have found that half experience at least one hypoglycemic episode, with the highest rates occurring on the day of admission. About one in five of those patients drops below 50 mg/dL, a level classified as severe hypoglycemia that can lead to confusion, seizures, or loss of consciousness.
Why Starvation Lowers Blood Sugar
Your body maintains blood sugar through two main systems. The first is glycogen, a stored form of glucose packed into your liver and muscles. When you eat normally, your liver keeps roughly a 24-hour reserve of glycogen that it breaks down between meals to keep blood sugar stable. The second system is gluconeogenesis, a process where your liver builds new glucose from amino acids, fats, and other raw materials.
In prolonged starvation, both systems eventually fail. Glycogen stores deplete within a day or two of not eating enough. Gluconeogenesis can compensate for a while, but it depends on a steady supply of building blocks from food and from your body’s own tissues. As malnutrition deepens, those supplies shrink. The liver itself starts to suffer: in patients with a BMI at or below 13, acute liver injury has been documented in which liver cells essentially consume themselves through a process called autophagy. At first, this self-digestion is protective, helping the liver survive nutrient deprivation. But when starvation continues past a critical point, it destroys liver cells, crippling the organ’s ability to produce glucose at all.
How the Body Tries to Compensate
The body doesn’t give up easily. Several hormonal shifts work to keep blood sugar from dropping during chronic food restriction. Insulin secretion decreases, which slows how fast cells pull glucose out of the bloodstream. Growth hormone rises, which stimulates the liver to produce more glucose. Cortisol increases as well, making cells somewhat resistant to insulin so that glucose stays available in the blood longer. A hunger hormone called ghrelin also rises and appears to play a key role in maintaining glucose levels. In animal studies, mice that couldn’t produce ghrelin experienced profound drops in blood sugar during starvation, while those with normal ghrelin levels maintained more stable glucose.
These adaptations can hold blood sugar in a normal range for weeks or even months of restriction. That’s why someone with anorexia might not show low blood sugar readings early in their illness. But the compensatory systems have limits. As the body runs out of fat and protein to convert into fuel, and as the liver sustains damage from prolonged starvation, these defenses collapse. When they do, blood sugar can plummet rapidly.
When the Risk Is Highest
Hypoglycemia in anorexia tends to cluster around two critical periods: at the lowest points of starvation and, paradoxically, during the early stages of refeeding.
During severe starvation, the danger is straightforward. The liver’s glycogen is gone, gluconeogenesis substrates are depleted, and the liver itself may be damaged. Blood sugar drops because the body simply has no way to produce enough glucose. This is when hypoglycemic coma becomes a real possibility. A review of case reports found that out of nine patients with anorexia who developed severe hypoglycemia, six died.
During refeeding, the mechanism is different but equally dangerous. When someone who has been starving begins eating again, the incoming food triggers a surge of insulin from the pancreas. Normally, the liver would counterbalance this by releasing stored glycogen. But in a malnourished person, those glycogen reserves are empty. The insulin pushes glucose into cells faster than the liver can replenish it, and blood sugar crashes. This is one component of refeeding syndrome, a broader set of dangerous fluid and electrolyte shifts that can occur when nutrition is reintroduced too quickly.
Nocturnal and Postprandial Episodes
Blood sugar drops in anorexia don’t only happen during obvious crises. Continuous glucose monitoring has revealed that patients can spend remarkably long stretches in hypoglycemic territory without realizing it. One case study using a continuous glucose monitor documented over 12 hours per day spent in hypoglycemia, with drops occurring both after meals and overnight.
Nocturnal hypoglycemia is particularly concerning because it happens during sleep, when a person can’t recognize symptoms or respond by eating. Overnight, the body relies entirely on the liver to maintain blood sugar, and a malnourished liver may not keep up. Postprandial hypoglycemia (drops after eating) appears to involve an exaggerated insulin response. In some cases, this pattern persists even after a patient begins regaining weight, suggesting that the pancreas’s insulin-release mechanism takes time to recalibrate after rapid weight changes.
What Hypoglycemia Feels Like
Mild hypoglycemia typically causes shakiness, sweating, a fast heartbeat, irritability, and difficulty concentrating. You might feel suddenly anxious or lightheaded. These symptoms overlap with general feelings of hunger or anxiety, which can make them easy to dismiss, especially for someone already accustomed to ignoring hunger signals.
As blood sugar drops further below 54 mg/dL, symptoms become more serious: confusion, slurred speech, blurred vision, difficulty walking, and extreme fatigue. At the most severe levels, hypoglycemia causes seizures or loss of consciousness (hypoglycemic coma). In one reported case, a patient with anorexia who resumed eating developed severe hypoglycemic coma alongside acute liver injury about a week after restarting food, illustrating how refeeding and liver damage can combine to create a medical emergency.
Why It’s a Medical Emergency in Severe Anorexia
Hypoglycemia is dangerous for anyone, but it carries outsized risks in people with anorexia for several reasons. First, the body’s backup systems for correcting low blood sugar are already exhausted. A healthy person who becomes hypoglycemic will mount a hormonal response (releasing glucagon and adrenaline) that quickly mobilizes stored glucose. In severe anorexia, there is little stored glucose left to mobilize. Second, the heart is often already compromised by malnutrition, with reduced muscle mass, slow heart rate, and electrolyte imbalances. Hypoglycemia adds cardiac stress on top of an already fragile system, increasing the risk of fatal heart rhythm problems. The case of a 44-year-old woman with a five-year history of anorexia who presented in hypoglycemic coma and later experienced sudden cardiac death illustrates this intersection of risks.
Third, liver damage from starvation creates a vicious cycle. The liver is the organ most responsible for correcting low blood sugar, and when it’s injured, recovery from a hypoglycemic episode is slower and less certain. In a series of 12 patients with anorexia who developed acute liver failure, all had a BMI of 13 or below, and half arrived in hypoglycemic coma.
Signs to Watch For
If you or someone you know is living with anorexia, certain warning signs suggest blood sugar may be dropping to dangerous levels. Waking up drenched in sweat, feeling confused or disoriented in the morning, sudden episodes of trembling or heart racing between meals, and unexplained fatigue that comes in waves rather than steadily can all point to hypoglycemia. These symptoms are more concerning in someone with very low body weight, a long duration of illness, or known liver enzyme elevations.
Hypoglycemia in anorexia is not a minor nutritional side effect. It reflects a body running out of its last reserves, and its presence often signals that multiple organ systems are under serious strain.