The American Dietetics Association has some advice for people who want to gain weight. Yes, they’re out there, those people who have as much trouble putting weight on as most of us have keeping it off.  Theories run rampant, including one developed at Washington University that pinpoints a family of bacterial in your intestines that determines whether you use all the calories you take in or not.

The Dietetics Association has posted some tips on gaining weight without sacrificing nutrition. That’s what a lot of folks do, eat a high-calorie diet of junk food, desserts and other empty calories.

Here’s what the Dietetics Association suggests:

– Follow the MyPyramid guidelines and eat a variety of foods from all food groups.

– Pick foods with concentrated calories. Fortify soups, casseroles and milk with dry milk powder.

– Enjoy higher-calorie condiments, such as a spoonful of sour cream on a cup of chili. Or garnish salads with sources of healthy fats such as olives, avocados, nuts and cheese.

–if you tend to have a small appetite, try eating five to six small meals throughout the day.

– Drink beverages before and after meals, not with them. That leaves more room for food during your meal.

Of course the Dietetics Association wants you to contact a registered dietitian to keep you on track.