Underweight is a term describing a person whose body weight is considered too low to be healthy. The definition usually refers to people with a body mass index (BMI) of under 18.5 a weight 15% to 20% below that normal for their age and height group.
Low weight may be due to improper diet,reduced assimilation from intestine, illness,metabolism ,genetics etc .
Thus first we have to rule out any such condition, with this have a healthy diet with more proteins (legumes,eggs,fish,lean meat),vegetables and fruits,drink plenty of water and go for regular exercise .
A homoeopathic constitutional treatment will definitely help you a lot.
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