AS Symptoms - Loss of Appetite

Reviewed by: HU Medical Review Board | Last reviewed: February 2019 | Last updated: October 2021

The most common symptom of ankylosing spondylitis (AS) is pain in the joints, which occurs due to the inflammation in the joints and in the entheses (the points where ligaments and tendons attach to the bones). The joint pain commonly begins in the sacroiliac joints, those located where the base of the spine meets the pelvis, although different people with AS can have their symptoms begin in different joints of the body. In addition to joint symptoms, AS may cause other extra-articular (beyond the joint) symptoms, including eye inflammation (uveitis), fever, fatigue, and loss of appetite.1,2

It's important to note that each person with AS can have a different set of symptoms, or presentation, of the disease. Symptoms of AS most often begin in late adolescence or early adulthood (before age 45), although some people experience the onset of symptoms in childhood or later in life.1

Why does ankylosing spondylitis cause loss of appetite?

Although AS is known for causing inflammation in the joints, inflammation is increased in the whole body in a person with AS. Some of the systemic (whole body) effects of chronic inflammation include fever, fatigue, and loss of appetite.

The inflammatory response is the immune system's natural reaction when cells are stressed or damaged, or when there is a foreign invader (like a viral, fungal, or bacterial infection). Although inflammation in AS is viewed as having negative consequences, it is a necessary process in the body to recruit defense systems, remove damaged or diseased cells, and trigger repair mechanisms.3

In addition to the inflammation from AS causing a loss of appetite, fever and fatigue (other extra-articular symptoms that can occur in someone with AS) can also cause someone to not feel like eating.

The challenge of diagnosing ankylosing spondylitis

Diagnosing AS is not a simple or straightforward process. On average, it can take 8-11 years from when symptoms begin to when a person receives a diagnosis.4 One of the reasons diagnoses in the early stages can be so challenging is that early signs, like low back pain or loss of appetite, are common and can be caused by a variety of other conditions. It can be very challenging for a diagnosis of AS to be made when patients only have non-joint (non-articular) symptoms.5

Tips for managing weight loss with AS

When a person loses their appetite, they lose the desire to eat and do not experience hunger. In medical terms, this is called anorexia. Brief periods of anorexia may not cause significant problems, but a prolonged loss of appetite can lead to weight loss, a reduction in energy, and increased fatigue. If anorexia continues, it can lead to serious complications.6

Strategies to help manage loss of appetite include6:

  • Eating small meals or snacks throughout the day (every 1-2 hours).
  • Avoid skipping meals, even if you only eat a few bites.
  • Preparing a variety of foods.
  • Making foods visually appealing.
  • Having high-protein, high-calorie snacks on-hand.
  • Engaging in light exercise (like walking) before meal time to stimulate appetite.
  • Eating with others in a pleasant, relaxed atmosphere.

After a person is diagnosed with AS and treated appropriately, the underlying inflammation is reduced and the appetite generally returns to normal.

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