Dear XXXXXXX.
I am happy that you are conscious about your weight at age 28.
At age 28, your height 172 cm appears appropriate for weight of 62 Kg. People whose BMI is within 18.5 to 24.9(like your case) possess the ideal amount of body weight, associated with living longest, the lowest incidence of serious ilness, as well as being perceived as more physically attractive than people with BMI in higher or lower ranges.
So your weight is medically normal and healthy.

I would like to know the reason for which you would like to increase weight.
All are born with some potential for weight and height, that gets modified by hormonal effects, diet and environment. Parental heights and weights at respective age do have some binding on weight and height.
You just need to maintain weight and not gain weight.
On an average you should need to meals and 2 snacks a day amounting to around 2500 cal per day.With daily light exercises to keep you fit.

people eat heavy proteins, excess egg/meat, excess fats and even steroids to gain rapid weight, which in your situation doesn't appear sound.
If the reason for weight gain is cosmetic ( like say movie shooting), illness (recovery from TB), matching with spouse etc, all may have different natural or unnatural ways of weight gain. Commercial formulas that often claim rapid weight gain, do contain harmful chemicals often.

Please write back the exact reason, and whether you would really like to increase weight and why, so i can guide you further.

Thanks.

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