Skip skinless chicken breast; go for chicken thighs or legs. Brisket is the most calorie-dense cut of beef. Substitute pork shoulder roast for ham or pork loin. Whole milk, not skim. Don’t bother with ‘lite’ or low-fat products.
Add healthy fats: coconut oil, avocados, nut butters. Note: truly natural peanut butter has 2 ingredients – peanuts and salt. Period.
Sugar isn’t a healthy, or efficient, way to add calories. Excessive sugar has been linked to diabetes and heart disease (as if you need more to deal with!), and anyway, a gram of fat has 9 calories vs only 4 in a gram of sugar. And no, fat doesn’t necessarily cause heart disease. Recent research shows that the type of fat makes all the difference.
Crunchy/crumbly, e.g., chips, nuts – You can still get the flavor of chips or crackers by grinding them up and mixing with a little dip. For recipes using ground beef, skip the step of browning it – don’t need crispy bits. For the flavor of bacon without the crunch, use bacon grease.
Sticky, e.g., peanut butter, fresh bread or flour tortillas – mix peanut butter with applesauce or mashed banana. For bread, lightly toast (but not so much that it becomes crumbly).
Flimsy, e.g., lettuce – if you don’t mind wilted lettuce, load on the dressing! Otherwise the easiest way to get your leafy greens is to add fresh or frozen spinach to whatever you can – soups, sauces, casseroles, omelets, even smoothies (usually fruit completely masks the flavor).
Thin liquids, e.g., broth soups, water and other beverages – you have to stay hydrated, so this is very important. Add pureed vegetables or mashed potatoes to soup. Use unflavored gelatin to thicken cold beverages. In smoothies, a banana thickens better than berries, or add peanut butter.
You can almost always use a food chopper or processor to get the desired consistency of whatever your family is having for dinner. Or adapt your favorite recipes to be ready-to-eat: Grind meat and chop ingredients before cooking.
Use small pasta (e.g., orzo) instead of noodles. At some point I found it easiest to have everything the same texture instead of switching between different foods, so I converted to casseroles.
Homemade protein shakes and smoothies are healthier than Boost and Ensure-type products. The highest-calorie powder I have found is Orgain Organic Meal Replacement.
A high-speed blender like Vitamix or NutriBullet does the trick. Pasta and stuffing can get sticky (literally—flour + water = paste) unless there is enough fat or other ingredients. Rice and other grains get thicker the longer they sit. When you get to the point where it takes a while to swallow each bite, you might want to reduce seasonings.
You can still use pureed meals, protein shakes and smoothies through the tube, just add more liquid as needed.