healthy childrens meal plan for gainig weight

Hello. I'm 34 year old mother and I'm pretty worried about my two little sons’ health. One is 5 and the other 6 years old.
The thing that is worrying me the most is that they are very skinny and I'm afraid that this could cause a bad impact on theirs general health state.
So, in fact, I'm interested to find out is there any healthy way for them to gain some weight.
A friend of mine recommended me that I should give them more fatty food but I don’t thing this would be that healthy plan. Please tell me- is there any healthy meal plan for gaining weight?

You are totally right- eating greasier and fat-filled food will not help your children to gain some healthy body weight and improve their immune status. The main fact about this you should know is that winning at weight gain comes down to pairing a balanced eating pattern with regular physical activity. I would not suggest giving them some big meals. Rather than struggling to eat a few really big meals, plan three regular meals plus two or three snacks for them.
Make meals a little larger or more calorific with a lot of accompanying food types such as bread, cereal, rice, and pasta: granola, bagels, biscuits and cornbread. Although exercise helps to burn calories, it's crucial to include some form of activity into your plan because it will straighten their muscles and bones.