Unexplained Weight Gain
Unexplained weight gain -- more than 2kg/month or 7% of body weight without a clear cause -- warrants medical evaluation, per current obesity management guidance.
Symptoms
Weight gain that occurs faster than expected from diet and activity changes alone, sometimes alongside fatigue, cold intolerance, mood changes, or changes in skin and hair -- clues to an underlying cause.
Causes and risk
Thyroid dysfunction, certain medications (some antidepressants, antipsychotics, steroids, and diabetes medications), Cushing syndrome, menopause, and PCOS are all recognized medical causes of weight gain beyond diet and activity alone.
How it is evaluated
Baseline evaluation includes TSH/free T4, glucose and A1c, and a full medication review; Cushing syndrome screening (a 1mg dexamethasone suppression test, 24-hour urinary free cortisol, or late-night salivary cortisol) is used when clinical suspicion is present, per Endocrine Society-aligned guidance.
Treatment
Treatment addresses the underlying cause first; for weight management itself, lifestyle intervention is foundational, with FDA-approved medications (including GLP-1-based options) considered per the American College of Physicians 2026 living guideline, which does not endorse supplement-only weight-loss regimens.
When to seek care
Rapid, unexplained weight gain with swelling in the legs, shortness of breath, or reduced urination could signal heart or kidney trouble and should be evaluated promptly.