How to gain weight for underweight skinny people
Underweight can gain weight by high calorie foods and lifestyle
changes. The foods must be judged against a five  point criteria
1. High Calorie,  2. Moderate fats,  3. High Protein,  4. High Fiber
5. High nutrition
High calorie foods may help you gain body fat. Resistance exercise
will help to gain muscle mass.
Weight gain program needs patience. It takes longer for underweight
person to gain weight than to lose weight. Overweight person can gain
weight faster than an underweight person

Being underweight may impact your health:
- Low immune response to infections and diseases
- Women may postpone menstruation, even quit menstruating.
- Elderly woman are at higher risk of osteoporosis and hip fractures.
- Men have higher risk of Erectile Dysfunction.

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