1. Hidden calories — sugary drinks, alcohol, snacks, sauces and oils can add many calories without making you feel full.
2. Low physical activity — sitting for long periods reduces the calories you burn each day.
3. Slow or reduced metabolism — metabolism varies between individuals and can change with age, muscle mass and activity.
4. Poor sleep — inadequate sleep can increase hunger and cravings and affect hormones involved in appetite.
5. Stress — chronic stress can influence appetite, food choices and fat storage.
6. Hormonal conditions — problems such as hypothyroidism or PCOS can contribute to weight gain.
7. Medications — some antidepressants, steroids, antipsychotics, diabetes medicines and others can cause weight gain.
8. Loss of muscle mass — having less muscle can reduce your daily energy expenditure.
9. Fluid retention — rapid increases on the scale aren’t always body fat; salt intake, hormonal changes and certain medical conditions can cause water retention.
10. Underestimating portions — even healthy foods can contribute to weight gain if total calorie intake consistently exceeds your body’s needs.
Important: If the weight gain is sudden, unexplained, or accompanied by swelling, shortness of breath, extreme fatigue, menstrual changes, or other symptoms, it’s worth seeing a doctor for assessment.