Thanks for posting your query.
First you need to sort out the reason of being underweight
. it may be due to nutritional deficiencies for that additional high calorie supplements like Boost Plus is prescribed but it may be due to abnormal absorption of diet due to many reasons.
Continuous large amount of High calorie supplements can disturb Stomach and cause stomach fullness, nausea
. In such cases it may be stopped for certain periods or dosage and frequency is reduced.
Vegetables and juices are important part of balance diet but adequate amount of protein is also necessary which is present in meat/dairy products, legumes and nuts. You may like to visit your doctor to rule out malabsorption
and its causes.
Hope it helps.