Sudden, rapid weight gain all over the body is typically a symptom of an underlying medical condition rather than simple fat accumulation. Common causes include hormonal imbalances like hypothyroidism, Cushing?s syndrome (excess cortisol), fluid retention, or side effects from medications like corticosteroids. There is no single pill to prevent or stop sudden weight gain. Instead, treatment must target the root cause. For example, thyroid hormone replacement is used for hypothyroidism, while specific medications or surgery address Cushing?s. Please consult a doctor immediately for blood tests, hormone panels, and a medication review to determine the exact cause and receive the appropriate targeted treatment.