Whey protein helps to gain quality muscle weight. Weight gainer/ Mass gainer helps to gain muscles plus lots of fats.
Please don expect miracle results by drinking 3 tubs of weight gainer. And also are you eating 5 protein meals a day?
If you don't train hard and correctly you won't gain muscles too.
Whey protein or any protein powder is suitable for all body types. It is also suitable for skinny people who wants to gain weight.
There is no such thing skinny people should take weight gainer. Weight gainer/ mass gainer is loaded with fructose and simple sugars to jack up your insulin to cause your body to convert sugar into body fat. When your body stores more fat, your weight will go up. Hence it's called weight gainer.
Fructose and the simple sugars also cause your triglyceride and cholesterol levels to increase, and putting you at risk of getting cardiovascular disease in the long run.

I have 2 friends who had been drinking weight gainers (popular brands) for years. They went for medical check up. One had fatty liver and both had hi triglyceride and cholesterol levels. One had hi blood sugar level. I put them on low carb diet with plenty of whey protein and healthy fat. In less than 6 months their conditions had been reversed.

Their previous diet was egg whites and lean meat, and low fat. Under my therapy, they ate whole eggs plus lots of oil. (no weight gains)

Good luck to weight gainer drinkers.

Why no one suggested nuts and olive oil to be blend inside his shake ?

beside nuts and olive oil, also add more rolled oat to be blend to intake more calories. this are all good quality food

How does olive oil taste in a shake? Would it taste weird?

Down it like a man! Lol. Get the fruity tasting olive oil

Think I need to eat more meals. Probably tuna sandwich... Thanks for the encouragement and advice.

eat bigger portion of meat in every meal.. and yeah snacks wit protein, nuts, sandwich.. trust me you will know how little u used to eat once u gained the weight haha.. gotta lift hard and eat a lot loh. general rule that you cant go wrong with.

1 way is to count calories. use fitday.com it's free, you should be eating (your weight in pounds) x (20) = the total calories you should eat in a day. I counted calories too using fitday.com and followed strictly to eat that amount of calories or more for about a week or so.. got 1kg gain ahhaa.. provided you train 3 times a week.. squat/deadlift.. yeah.

Just some updates.

After 2 weeks of workout, 4-day programme, do 1 day, rest 1 day, then 3 times whey protein daily, I gained 3 kgs in 2 weeks.

Gotta work harder.