Systemic Lupus Erythematosus (SLE), commonly known as lupus, is a chronic autoimmune condition where the body’s immune system mistakenly attacks its own healthy tissues. Lupus causes a wide array of symptoms, and fluctuations in body weight are a common experience. Understanding that weight changes can be an expected part of living with this condition helps validate a patient’s experience.
Mechanisms Behind Unintended Weight Loss
Weight loss in lupus is often unintentional and results directly from active disease. A major factor is the high level of chronic inflammation during a lupus flare. This inflammation increases the body’s overall metabolic rate and energy expenditure, burning calories faster than normal as the immune system works overtime.
This sustained metabolic stress can lead to cachexia, characterized by involuntary weight loss and the wasting of both fat and muscle stores. Cachexia is driven by the underlying disease process and pro-inflammatory mediators, forcing the body to break down its own tissues for energy. Active lupus often causes gastrointestinal symptoms like nausea, diarrhea, and abdominal pain, which reduce the desire to eat.
Loss of appetite (anorexia) is a frequently reported symptom during periods of high disease activity, contributing to poor nutrient intake. Complications such as inflammation in the digestive tract or mouth sores can make eating painful or difficult. Lupus can also affect the body’s ability to properly absorb nutrients, further contributing to weight loss.
Understanding Medication-Related Weight Gain
While the disease can cause weight loss, the primary treatment for active lupus often causes weight gain. Corticosteroids, such as prednisone, are effective anti-inflammatory medications but are notorious for causing significant weight changes. Up to 70% of people on long-term corticosteroid therapy report weight gain.
Corticosteroids mimic cortisol, the body’s natural stress hormone, which has multiple metabolic effects. A common side effect is a substantial increase in appetite, leading to greater calorie intake. The medication also alters how the body processes and stores carbohydrates and fats, driving fat accumulation.
Fluid retention is another major contributor to weight gain from corticosteroids. The medication changes the electrolyte and water balance, causing the body to hold onto excess fluid. This weight gain often involves the redistribution of fat to central areas, leading to a characteristic “moon face,” a widening of the abdomen, and sometimes a “buffalo hump.” Other medications used to manage lupus, including some antidepressants, can also contribute to weight gain.
Interpreting Weight Changes: Flare vs. Side Effect
Distinguishing the cause of a weight change is important for managing lupus, as it dictates whether treatment needs adjustment. Unexplained weight loss, especially a rapid loss of more than 5% of body weight, is a classic sign of active, uncontrolled disease. This weight loss is typically accompanied by other flare symptoms, such as high fever, profound fatigue, and severe joint pain.
In contrast, weight gain appearing shortly after starting or increasing a corticosteroid dose, like prednisone, strongly suggests a medication side effect. This weight change is often accompanied by increased hunger and visible signs of fluid retention, such as swelling in the ankles or face. Tracking symptoms and medication changes alongside weight helps the healthcare team determine if the fluctuation is a sign of a disease flare or a treatment side effect warranting a medication taper or substitution.
Managing Healthy Weight Fluctuations
Maintaining a stable, healthy weight requires a proactive approach between the patient and the rheumatologist. If you experience sudden or unexpected weight changes, communicate this immediately with your healthcare provider. They may need to review current medications and screen for other conditions, like thyroid problems, that affect weight.
Dietary Management
During periods of low appetite associated with a flare, focus on consuming smaller, more frequent meals composed of nutrient-dense foods, such as lean proteins and whole grains, to prevent malnourishment. When managing fluid retention from steroids, staying well-hydrated and reducing sodium intake can help the body manage excess water.
Physical Activity
Gentle, low-impact movements like walking, swimming, or yoga are excellent for maintaining muscle mass and promoting a healthy weight without placing undue stress on painful joints.