By Nutrition

Q: Do grapefruit and vinegar really make your body burn more calories?

A: No. Both may be helpful in weight control efforts, but not because of some magical ability to melt fat or burn more calories. Vinegar has only a few calories per tablespoon, so using it instead of fat to flavor vegetables will save calories.

Grapefruit, with less than 40 calories in one half, can do a lot to satisfy your appetite.

The bottom line is that these foods only make you lose weight as part of a balanced diet in which you take in fewer calories than you burn up each day.

Q: What size portions do my children need?

A: You don’t want to provide children with too little to meet their needs for growth.

On the other hand, servings that are too large tend to overwhelm children and they may have trouble eating all of them. Serving small portions to young children is often the best way for them to learn to eat only until satisfied, instead of overeating. Start kids off with less and encourage them to ask for more if they’re still hungry.

For each year of age, the American Dietetic Association recommends one tablespoon of every food offered at a meal. That means 3-year-olds would start with three tablespoons of every food offered, and if they eat it all they can ask for more. Don’t make the mistake of scolding children for not finishing all you have served.

If you view this a waste of food, serve less instead of forcing them to overeat.

Don’t hand out snacks an hour after dinner if they are suddenly hungry because they ate too little at the previous meal.

Eventually, they will learn to gauge their own appetites and get most of what they need at regular meals.

Q: Does caffeine cause high blood pressure?

A: When we are under stress, our levels of certain stress hormones increase, which also raises our blood pressure.

A number of studies have now demonstrated that the caffeine equivalent of two or three cups of regular coffee also increases the level of these hormones and tends to raise both systolic and diastolic blood pressures by three to six points each.

Caffeine also increases the blood pressure response to stress, and in people with borderline blood pressure, this is enough to cause high blood pressure for two or more hours after consuming caffeine.

Although these effects appear at all ages, some studies show that caffeine’s effect on stress hormones and blood pressure becomes even stronger as we get older.

Q: Since I don’t eat as much fiber as recommended, is a fiber supplement a good option?

A: Supplements can be useful when extra amounts of fiber are needed to help lower blood cholesterol or promote regularity. But fiber supplements cannot be used as a substitute for natural sources of fiber: vegetables, fruits, beans and whole grains.

Different plant foods supply several different types of fiber that, in turn, seem to provide different kinds of benefits.

Q: If snack foods are labeled “baked” does this mean they are low-fat?

A: No. Deciding whether processed foods are low-fat depends not only on whether they are cooked in fat, but also on how much fat is contained in the ingredients.

Baked chips and crackers might be low in fat, but don’t count on it. Check the fat content listed on the nutritions facts panel. Then be sure to adjust the fat and calorie content listed to match the portion size you are likley to eat.

Q: When food lables list “grams” of sugar in a food, what does that mean?

A: A gram is a unit of measuring weight. In the case of sugar, a measuring of one teaspoon weighs about four grams. So, if a label says a food contains 12 grams of suagr, that amount is equal to about three teapsoons of sugar.

- By Karen Collins, 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.