Welcome to icliniq.com.
Yes, I can understand that weight gain can be difficult for some people - but surely it is possible. Your wife needs to add at least 6 to 7 kg weight.
You need to eat the food that you like as this will help you eat more than usual. So, you need to take the kind of food that you like for example spicy food, veg or non-veg diet, etc.
The calorie intake has to be higher than what you regularly take - this also means that you need to take greater quantity of food.
You need to make a list of foodstuffs that you like and stick it on your refrigerator. For example, bananas, apples, peanuts, milk, chocolates, chips, french fries, ice-cream, almonds. Also, make a list of items for lunch and dinner that you like and cook them frequently.
Exercising: If you are doing any high-calorie burning exercises then you need to switch to other exercises for muscle training and less cardio workouts.
Dietician: constant follow-ups with your dietician will help you with progress of weight gain - always keep a dietician in the loop.
Add-on meal: start intake of one small extra meal other than your regular meals and do this consistently, over two months you will see the difference.
Protein supplements: powder protein supplements available in the market needs to be taken twice daily with milk. Do this consistently to see a change.
Consistency: is the key to success, so do these things regularly and only then you will see the results.
Sleep: you need to sleep for at least eight hours daily for a healthy body, and you can also add on another hour if you like as you do not lose much calories while asleep.
Fruits: make it a point to eat one fruit after lunch and one after dinner. They are great add-ons for good calorie intake and this is a great idea and a must.
This is only a second opinion platform. This professional advice provided by me stands subject to the actual examination of report/image and is based entirely on inputs provided to me. It should be correlated with clinical findings.
For more information consult a family physician online --> https://www.icliniq.com/ask-a-doctor-online/family-physician