Brief Answer:
Get evaluated for organic causes.

Detailed Answer:
Welcome to Healthcaremagic.
Hi, I am Dr Anshul Varshney , I have read your query in detail , I understand your concern.
If you are unable to gain weight, you should be evaluated for organic causes behind it. A lot many times, not able to gain weight is due to many issues like Malabsorption syndrome, Intestinal Tuberculosis, Acid reflux, Hyperthyroidism. So, a symptom based evaluation is required to rule out these causes.
People having Malabsorption syndrome like celiac disease are allergic to wheat products causing weight loss, pain abdomen, loose stools, anemia. In such scenario, we order Anti TTG Antibody test which helps in diagnosing celiac disease.
In case you have fever, weight loss then you would require evaluation for intestinal tuberculosis, for which you need to get initially an Ultrasound abdomen.
In people suffering from Hyperthyroidism, basal metabolic rate is high leading to weight loss. They also have tachycardia, anxiety, frequent loose stools, exopthalmos. So, if you have any of these then a thyroid profile is required.
If no cause is found, or you don't have any such symptoms that your issue might be just constitutional that is it's your body's habitus.
For this, you should not take any medications because most of the weight gain medications contains steroids, which cause rapid increase in weight but you will be fighting with the side effects all your life.
You just need to increase protein, fruits like banana , XXXXXXX in diet. Take more of milk and milk products. You should exercise regularly. You may take good protein powder as a nutritional supplement in moderated doses. But make sure that the protein powder should be medicated one and not the famous ones for body building.
This is the only safest and most effective way to gain weight.

This is my personal opinion based on details available here. If you still have any other query, you may please ask me.
Stay Healthy.
Dr Anshul Varshney , MD

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Brief Answer:
You can buy Proteinex.

Detailed Answer:
Hello, There are lot protein powders available in the market with various names. Most commonly used one is Proteinex. You may take it but remember that excess of everything is bad. So, you should be taking it in moderated doses only.
If you have any further query, please ask me.
Stay Healthy.

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Brief Answer:
Can be taken .

Detailed Answer:
Hello. Yes Whey protein is considered good and safe if taken in moderated doses. Make sure you buy whey protein after searching properly about the brand to get 100% genuine whey protein.
I hope it helps

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