Hi welcome - I always advice first try & practice enough carbs enriched with high quality all types of protein can be received from daily foods, Still you can add FRESUBIN / PROTENEX/ ENSURE with milk two times.

You can simply just gain weight by balanced diet and regular exercise. Exercise will help gain your stamina and diet will help retain your physical health and nourish your body. You can try some weight gain shakes rather than supplementing yourself with market products. For weight gain diet plan and shakes recipe, contact me at NUTRIFIT WELLNESS. Healthy regards from Dietician Shradha Srivastava. Thankyou.