While many associate illness with weight loss, some individuals experience weight gain during sickness or recovery. This unexpected increase can be confusing. Understanding the various factors contributing to this phenomenon can help clarify the process.
Physiological Mechanisms Behind Weight Gain
Illness often triggers physiological changes leading to temporary weight gain. Inflammation, a natural immune response, can cause fluid retention (edema). This fluid buildup manifests as swelling in areas like the legs, ankles, feet, and face, adding to body weight.
Illnesses requiring bed rest or causing significant fatigue can lead to a metabolic slowdown. Decreased physical activity means fewer calories burned, contributing to weight gain if caloric intake remains unchanged or increases. The stress of being sick also triggers hormonal shifts. The body releases stress hormones like cortisol, which influences metabolism, promotes fat storage (particularly abdominally), and can stimulate appetite.
While some illnesses suppress appetite, others might increase it or lead to cravings. During sickness or recovery, individuals may seek comfort foods high in calories, fats, or sugars. This increased consumption, combined with reduced energy expenditure, can contribute to weight gain.
Medication-Induced Weight Changes
Medications prescribed for illnesses can also contribute to weight fluctuations.
Corticosteroids, such as prednisone, are known for side effects including increased appetite, fluid retention, and changes in fat distribution. These drugs can cause a characteristic “moon face” or “buffalo hump” due to altered fat storage.
Certain antihistamines, commonly used for allergies, have been linked to weight gain. Histamine naturally reduces appetite, and blocking its effects can lead to increased food intake. Long-term antihistamine use is associated with obesity.
Antidepressants, prescribed to manage mood changes with chronic illness, can also affect body weight. Some classes, including tricyclic antidepressants, mirtazapine, and certain long-term SSRIs, are associated with weight gain. This can occur by influencing metabolism or increasing cravings for carbohydrate-rich foods.
Lifestyle Adjustments During Sickness
Behavioral changes and lifestyle factors also contribute to weight gain during illness.
Reduced physical activity is common when sick, as fatigue and malaise limit movement and energy expenditure. Bed rest or staying home more often means fewer calories are burned through daily activities.
Dietary habits often shift when feeling unwell. Many individuals turn to comfort foods, which are high in calories, fat, and sugar, as a coping mechanism. Lack of energy to prepare healthy meals can also lead to reliance on more convenient, less nutritious options.
Sleep patterns can be significantly disrupted during illness, whether through excessive sleeping or insomnia. Both insufficient and excessive sleep can impact hunger hormones and metabolism, contributing to weight gain. The stress of being sick can also lead to emotional eating, where food is consumed to alleviate discomfort or anxiety.
When to Seek Medical Guidance
If weight gain is persistent or significant during or after an illness, consult a healthcare professional. Rapid weight gain (e.g., 2-3 pounds/day, 5 pounds/week, or 5% of body weight/month) warrants medical attention. This can indicate an underlying issue requiring diagnosis.
Seek guidance if weight gain is accompanied by other concerning symptoms. These include severe swelling, lingering fatigue, new or unexplained pain, changes in bowel habits, vision disturbances, hair loss, feeling unusually cold, or heart palpitations. These symptoms could suggest an undiagnosed condition, such as a thyroid disorder, Cushing syndrome, or kidney or heart problems.
Discuss any new or worsening symptoms, including weight changes, with a doctor. If medication side effects are suspected, a healthcare provider can evaluate options and adjust treatment as necessary. Never discontinue prescribed medications without medical consultation.