Anorexia nervosa produces a wide range of symptoms that go far beyond weight loss. The physical signs include a dangerously slow heart rate (sometimes dropping to 40-50 beats per minute), low blood pressure, loss of menstrual periods, and fine downy hair growing on the body. But many of the earliest and most important symptoms are behavioral and psychological, appearing well before the physical damage becomes obvious.
Physical Signs of Anorexia
The body responds to prolonged calorie restriction in predictable ways. As energy intake drops well below what the body needs, vital signs change: resting heart rate slows, blood pressure falls, and core body temperature drops. Skin becomes dry or scaly. Hair on the head thins and becomes brittle, while a soft, downy hair called lanugo grows on the arms, face, and torso as the body tries to insulate itself. Nails become brittle. Muscle mass visibly decreases.
For women and girls who aren’t on hormonal birth control, menstrual periods often stop entirely. The fingertips and toes may develop a bluish tint from poor circulation. Dehydration is common and contributes to dizziness, fainting, and fatigue. These physical symptoms tend to worsen gradually, which can make them easy to dismiss in the early stages.
Behavioral Warning Signs
The behavioral changes around food are often the first things that family and friends notice. Common patterns include skipping meals, eating unusually small portions, refusing foods with sugar or fat, and a growing rigidity about what counts as “acceptable” to eat. Some people develop rituals around meals: cutting food into tiny pieces, rearranging it on the plate, or eating extremely slowly.
Exercise habits often shift dramatically. A person may begin working out far more frequently or intensely than before, sometimes exercising through injury or illness. Social withdrawal is also typical, especially around situations that involve food. Someone who used to enjoy family dinners or eating out with friends may start finding reasons to avoid those gatherings entirely.
Other behaviors that point toward anorexia include calorie tracking that becomes obsessive, wearing baggy or layered clothing to hide weight loss, and frequent comments about weight or appearance. In the binge-purge subtype of anorexia, a person may also use laxatives, induce vomiting, or misuse diuretics.
Psychological and Cognitive Symptoms
Starvation changes how the brain works. Concentration becomes difficult. Decision-making slows down. Thinking becomes more rigid and inflexible, with a narrowing focus on food, calories, and body size that crowds out other interests. Irritability increases, and emotional responses can feel blunted or unpredictable, with anxiety and mood swings becoming more frequent.
Two psychological features define anorexia at its core. The first is an intense, persistent fear of gaining weight that doesn’t ease even as the person becomes dangerously thin. The second is a distorted perception of body size: the person genuinely cannot see their body accurately. They may believe they are larger than they are, or they may tie their entire sense of self-worth to their weight and shape. These aren’t choices or vanity. They are symptoms of the illness itself, driven in part by the effects of malnutrition on the brain.
Early Signs That Are Easy to Miss
In adolescents especially, the earliest signs can look like normal behavior. A teenager who announces they want to “eat healthier” or starts reading nutrition labels closely might not raise alarm bells. But when that interest becomes inflexible, when entire food groups get eliminated, when portions shrink steadily, and when the person becomes anxious or defensive about eating, those are meaningful warning signs.
A useful screening tool asks five straightforward questions. Do you make yourself throw up because you feel uncomfortably full? Do you worry you’ve lost control over how much you eat? Have you recently lost more than 14 pounds in a three-month period? Do you believe yourself to be fat when others say you’re too thin? Would you say that thoughts about food and weight dominate your life? Answering yes to two or more of these suggests an eating disorder may be present.
Atypical Anorexia: Symptoms Without Low Weight
One of the most underrecognized forms of this illness is atypical anorexia, where a person restricts food intake severely and develops all the same medical and psychological symptoms, but started at a higher body weight and doesn’t appear underweight. Because they don’t “look” anorexic, these individuals are frequently overlooked by family, friends, and even healthcare providers. They may actually receive praise for their weight loss, which reinforces the dangerous behavior.
People with atypical anorexia experience the same fear of weight gain, the same distorted body image, and the same physical consequences of rapid weight loss, including heart rhythm changes, fatigue, difficulty concentrating, anxiety, and nutritional deficiencies. The speed of weight loss matters more than the number on the scale. Losing weight rapidly through severe restriction is medically dangerous regardless of starting size.
Serious Medical Complications
Prolonged anorexia causes damage that can be lasting. The heart physically shrinks. This myocardial atrophy reduces the heart’s pumping capacity and commonly leads to mitral valve prolapse, where a heart valve doesn’t close properly. Irregular heart rhythms become more likely, especially when electrolyte levels are disrupted by purging behaviors or severe malnutrition.
Bone density loss is one of the most concerning long-term effects. In anorexia, the body both breaks down bone faster than normal and fails to build new bone, creating a “double hit” that causes marked weakening. This can lead to osteoporosis even in teenagers and adolescents, and the damage may be permanent. The causes are interconnected: elevated stress hormones, low sex hormones, low body weight, and resistance to growth hormone all contribute.
Electrolyte imbalances, particularly low potassium, create the most immediate danger. Potassium is essential for normal heart rhythm, and severe depletion can trigger life-threatening cardiac events. A resting heart rate below 50 beats per minute while awake, or blood pressure dropping below 80 systolic, are red flags that signal the body is in serious medical distress.
Who Is Affected
Anorexia nervosa affects about 0.6% of adults over their lifetime. It is three times more common in women (0.9%) than men (0.3%), though it occurs across all genders, ages, races, and body sizes. It carries one of the highest mortality rates of any mental illness. The symptoms often begin in adolescence, but anorexia can develop at any age, and late-onset cases in adults are not rare.
Because the illness distorts self-perception, many people with anorexia don’t recognize or acknowledge their symptoms. The behavioral and physical signs visible to others are often the most reliable indicators that something is wrong.