By Karen Collins

Nutrition

Q: Because she wants to keep the food in her refrigerator cold, my mother leaves hot leftovers sitting on the counter to cool before she puts them in the fridge. Is this safe?

A: Once food is cooked, it should not be kept at room temperature for more than two hours, including serving, eating and cooling. Small amounts of bacteria that may be found in or on meat and other perishable foods reproduce rapidly at room temperature.

Q: Is ground turkey lower in fat than ground beef?

A: Not always. The fat content of any ground meat depends on how much fat is ground up along with the lean meat. Regular ground beef may be about 27 percent fat, a figure that represents the amount of fat found in the meat by weight, not by calories. Leaner choices, sometimes labeled ground round and ground chuck, are typically 15 to 20 percent fat. Check labels for the percent fat; if it’s not listed, ask the butcher.

Q: Is it true that some foods have “negative calories?”

A: Some fruits and vegetables are extremely low in calories: a medium stalk of celery has only six and a half-cup of cucumber slices seven.I have not seen any scientific evidence that states precisely how many calories our bodies burn up as we chew and digest these foods. That’s why the idea that these foods aid in weight loss because of “negative calories” is hard to prove. Research does show that when people eat hearty portions of fruits and vegetables, they tend to eat less of other foods. The result: a net drop in total calories that leads to weight loss.

- Collins is a registered dietitian for the American Institute for Cancer Research. Send your questions to “Nutrition-Wise,” c/o Town Crier, 1759 R St., N.W. Washington, D.C. 20009.