Re: Need high calorie low-fat food ideas
Potatoes are nutritious, pasta is basically just starch. Calories but few other nutrients.
Try some ultra-lean meats. Canned tuna has basically no fat, and he could mix it with a fat-free sauce instead of mayonnaise. Some cuts of turkey or skinless chicken are also good. And, surprisingly, beef liver. It's not fat-free, so he could only have small portions, but it's low fat, and it's high in protein, iron, and vitamin A.
Most vegetables have little fat. They aren't high calorie, but they do have vitamins he needs. Dried fruit is good, too. (Check the labels because some brands of dried fruit have oil added.)
Finally, nonfat dairy. Fat free cottage cheese and yogurt are high in nutrients. You can buy them plain and mix in whatever honey or fruit he likes.