Why Do Weight Changes Happen in Ankylosing Spondylitis?

Ankylosing spondylitis (AS) can affect your weight. It can either cause a loss of appetite, leading to unintended weight loss, or the pain and discomfort associated with AS can limit physical activity, resulting in weight gain.

This article discusses these connections and what you can do to maintain a healthy weight if you live with this disease.   

What Makes AS Worse, Losing or Gaining Weight?

The severity and symptoms of AS can vary from person to person. The relationship between AS and weight further complicates matters.

Research has found that neither being overweight or obese nor being underweight is good if you have AS. Both body types lead to increased disease activity, making symptoms more severe and responses to treatment less successful.

Unintended Weight Loss From Inflammation

Inflammation is the body's immune response to cell damage or infection. Ankylosing spondylitis is a chronic inflammatory condition that directly affects the spine's joints. In severe cases, broader effects include:

• Fatigue and lack of energy
• Fever
  
• Inflammation in the digestive system, such as Crohn's disease and ulcerative colitis
• Loss of appetite

As a result of these symptoms, eating healthy becomes difficult. Dietary changes may lead to unintended drops in weight and can cause malnutrition, a condition in which the body doesn't get the nutrients it needs. These are common complications of AS, and complications are more pronounced in people the longer they live with the condition.

Studies have linked these symptoms to increases in specific inflammatory biomarkers, which offer clues to identifying any underlying disease. Proteins, known as cytokines, are biomarkers that may directly affect appetite centers in the brain. One study found that about 23.8% of AS patients experience malnutrition.

Increased Joint Pain From Being Overweight

The stiffness, pain, and intense fatigue associated with AS can cause people to avoid physical activity and gain weight. Medications prescribed for the condition, tumor necrosis factor (TNF) blockers, can also cause weight gain as a side effect.

The added weight from being overweight or having obesity puts excess strain on the joints. People with AS experience more pressure on the vertebrae (the bones in the spine), which increases pain. This increased strain contributes to advanced disease progression and damage to affected areas.  

How to Reach a Healthy Weight With AS

Weight changes with AS can impact the progression of this disease. Maintaining a healthy weight is recommended to manage this condition.

If you aim to gain weight, here’s what you can try:

• Boosting your physical activity to stimulate your appetite
• Eating small meals throughout the day, especially if you get full quickly
• Eating nutrient-rich snacks throughout the day, such as nuts or dried fruit
• Incorporating healthy, unsaturated fats into your diet
  
• Making eating a social event and dining with others

If you aim to manage AS and lose weight, try the following:

• Avoiding foods with added sugars, salts, or refined grains
• Controlling your portion sizes during meals
• Emphasizing fresh fruits and vegetables
• Getting enough sleep
• Incorporating regular exercise
• Limiting saturated fat content
• Managing stress and anxiety
  

Obesity as a Risk Factor for AS

Research has found that the biomarkers associated with inflammation due to AS are also associated with obesity. This connection indicates that clinical obesity may be a risk factor for AS.

While the exact relationship is still being researched, there’s considerable overlap between clinical obesity and AS. A cross-sectional analysis of weight status in people with axial spondyloarthritis (AS is a severe form of spondyloarthritis) found that 22% of the subjects experienced obesity, compared to 15% of the general population participating in the study.

Summary

Ankylosing spondylitis (AS) has a complex relationship with body weight. In some, it causes unintended weight loss and malnutrition. Others with AS may gain weight due to inactivity from the condition. Being diagnosed with clinical obesity or overweight can make AS worse. Maintaining a healthy body weight by practicing moderate exercise, good sleep habits, and adhering to a well-balanced diet is vital in managing this disease.    

A Word From Verywell

It’s challenging to live with a chronic inflammatory condition like AS. Without a cure, there is always the risk of flare-ups and periods of pain and discomfort. However, with medical help and lifestyle changes, you can effectively manage this condition. The key is to be proactive; if you’ve been diagnosed with AS, talk to your healthcare provider and learn ways to manage your condition.