Advanced Underweight Risk Calculator

According to WHO, BMI below 18.5 is underweight. Thinness grades: Mild (17.0-18.49), Moderate (16.0-16.99), Severe (below 16.0). Severe thinness significantly increases health risks and mortality. Normal weight range is BMI 18.5-24.9.

Underweight risks include: weakened immune system, nutrient deficiencies (iron, B12, calcium, vitamin D), osteoporosis, muscle wasting, fertility issues, hair loss, anemia, fatigue, poor wound healing, and increased infection risk. Severe thinness (BMI below 16) significantly increases mortality risk.

To gain weight, eat in a caloric surplus above your TDEE. Gentle: +300 kcal/day (gain ~0.25kg/week). Standard: +500 kcal/day (gain ~0.5kg/week). Aggressive: +700 kcal/day (gain ~0.7kg/week). Our calculator determines your exact TDEE based on activity level and adds the appropriate surplus.

For muscle-focused weight gain: 1.6-2.2g protein per kg body weight. For a 55kg person, that's 88-121g daily. Spread protein across meals (20-40g per meal). Protein is essential to build muscle mass rather than just fat. Good sources: meat, fish, eggs, dairy, legumes.

Nutrient-dense, calorie-rich foods: nuts and nut butters (~600 kcal/100g), avocados, whole milk, cheese, olive oil, fatty fish (salmon), eggs, oatmeal, whole grains, dried fruits, potatoes, and smoothies with protein powder. Avoid empty calories from sugary/processed foods.

Timeline depends on weight deficit. At 0.5kg/week (healthy pace): 5kg deficit = 10 weeks, 10kg deficit = 20 weeks. Faster gains (0.7kg/week) are possible but may add more fat. Slower gains (0.25kg/week) maximize muscle-to-fat ratio. Patience and consistency are key.

Common underweight symptoms: chronic fatigue, feeling cold often, hair loss/thinning, brittle nails, dry/pale skin, dizziness, irregular periods (females), frequent illness, slow wound healing, difficulty concentrating, muscle weakness. Multiple symptoms suggest medical evaluation.

Yes, consult a doctor if: BMI below 17 (moderate/severe thinness), unintentional weight loss, multiple underweight symptoms, underlying conditions preventing eating, eating disorders suspected, or if weight gain attempts fail. Medical evaluation can identify underlying causes and ensure safe weight gain.

Yes! Resistance training stimulates muscle growth, so calories become muscle rather than just fat. Aim for 2-4 strength sessions per week targeting major muscle groups. Combine with adequate protein (2g/kg) and caloric surplus. Without training, excess calories mostly become fat.

If eating large meals is difficult, try 5-6 smaller meals. This makes hitting calorie targets easier. Example with 2500 kcal goal: 6 meals = ~420 kcal each. Add calorie-dense snacks: nuts, cheese, smoothies. Frequency matters less than total daily intake.

Common deficiencies in underweight: Iron (anemia, fatigue), Vitamin D (weak bones), Calcium (osteoporosis), B12 (fatigue, nerve issues), Zinc (hair loss, immunity), Protein (muscle loss). A blood test can identify deficiencies needing supplementation.

While metabolic rates vary, 'too fast to gain' is usually a myth. High metabolizers simply need more calories. Track intake—most people underestimate calories. If truly eating 3000+ kcal without gain, consider: absorption issues (celiac, IBD), hyperthyroidism, or high NEAT (non-exercise activity). Medical evaluation may help.

Weight gainers provide convenient high-calorie shakes (500-1000+ kcal). They can help when struggling to eat enough food. However, whole foods are nutritionally superior. Make homemade alternatives: blend oats, banana, peanut butter, milk, protein powder. Supplements should complement, not replace, real food.

Rapid weight gain (over 1kg/week) typically adds more fat than muscle, may cause digestive issues, and can overwhelm the body. Sustainable pace: 0.25-0.5kg/week. For severe thinness, doctors may recommend faster refeeding under supervision. Otherwise, slow and steady wins.

Unintentional weight loss causes: hyperthyroidism, diabetes, celiac disease, inflammatory bowel disease, depression, eating disorders, cancer, chronic infections, medication side effects, and malabsorption. Losing more than 5% body weight in 6-12 months without trying warrants medical evaluation.