DEAR DR. BLONZ: I have a math issue regarding body weight and body fat. If a pound contains 454 grams, and there are nine calories per gram of fat, please explain how a pound of body fat is said to contain only 3,500 calories. You and many others use this figure but the math does not add up. -- D.L., Poway, Calif.

DEAR D.L.: There are indeed 454 grams in a pound, as you point out. So how do we come up with 3,500 calories from a pound of body fat when 454 x 9 = 4,086 calories? To start with, consider that fat is our most calorie-dense substance and it is capable of providing an energy equivalent to nine calories per gram. It is utilized as the primary form of energy storage because humans, like other animals, need to be mobile. Imagine the image of a human with energy stores in the form of carbohydrate or even protein; if such were the case our bodies would need to take up over twice the space they do now.

Getting back to the math problem, the answer rests with the fact that adipose tissue in the body is not 100 percent pure fat. This tissue contains a small amount of water and some structural material, accounting for close to 15 percent of tissue weight. It is this nonfat portion that helps explain why a pound of body fat is said to contain approximately 3,500 calories worth of stored energy.

DEAR DR. BLONZ: I was wondering what your thoughts were regarding the use of sports drinks as a beverage for active children. -- E.F., Oakland, Calif.

DEAR E.F.: I would not consider a sport drink to be a universal go-to beverage for children; water fits that description. Next might be a nutrient-rich 100 percent fruit juice, ideally one from any of a variety of berries. Sports drinks can be helpful for those involved with hour-plus workouts or athletic events, in that they can help replace the sodium and potassium lost through perspiration. A small amount of sweetener helps make the drink more palatable, and it provides a small boost of the type of fuel that is in short supply during an extended workout. You don't want too much sugar as that can work at cross purposes by slowing absorption. I also advise against giving exercising children any drinks that contain stimulants, such as caffeine.

The journal Pediatrics found that an effective beverage contained, per 8-ounce serving, 14 grams of sugar (6 percent carbohydrate) and 110 milligrams of sodium (18 mmol/l sodium). See tinyurl.com/h9nne for more information. This is the same formula found in Gatorade and some other sport drinks. Check the Nutrition Facts label on any products before you buy.

I recommend that you make your own sports drink from fresh juices. Such a beverage provides the same nutrients as store-bought sports drinks, but contains genuine flavors and the added benefits of the fruit's phytochemicals. My recipe can be found at tinyurl.com/krkj8mx. You know your child best, so you should adjust the recipe accordingly.

Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.

DEAR DR. BLONZ: A friend of my daughter's has celiac disease and she will be coming for a holiday dinner. My question is: Do oats have to be eliminated from celiac diets, or is wheat the only problem? Is there any problem with the vinegar I might use in my salad dressing? -- S.P., Oakland, Calif.

DEAR S.P.: Gluten is a complex protein found in all forms of wheat, barley, rye and triticale, or any products that might be made from these grains, including modified food starches. Celiac disease, also referred to as celiac sprue, is an autoimmune disorder in which the body has an acute genetic intolerance to gluten. The intolerance is such that the presence of gluten causes severe intestinal inflammation, with the immune system damaging the small intestines in a way that prevents nutrients from being absorbed. Note that celiac disease is a different clinical entity from non-celiac gluten sensitivity, or gluten intolerance, where the body can experience transient negative gastrointestinal reactions to gluten without the severe intestinal tissue damage.

As regards oats and celiac, they were once on the prohibited list, but then there was some research indicating that individuals with celiac disease may be able to tolerate certified wheat-free rolled oats. There have been studies that conclude "yes" to oats, while others have concluded the opposite. There is then the issue of individual differences between celiac patients: Some tolerate oats while others cannot.

The essential element is that the oats have no cross-contamination from handling or processing in plants that also handle wheat or rye. Those with celiac disease should get assurances to that effect, either from the product label or directly from the manufacturer. Your acquaintance should talk about oats with the professional handling this aspect of her health care to decide whether an oat experiment may be in order.

As for vinegars, most tend to be made from other materials, including apples, corn, rice and grapes, and these have no gluten. One vinegar of concern is malt vinegar, as this has gluten-containing malt added. Again, you should check the label or with the manufacturer if you have questions.

For more information, check out the information page from the National Institutes of Health at tinyurl.com/385xee or the website of the Celiac Disease Foundation at celiac.org.

DEAR DR. BLONZ: Is it OK to mix soy and cow's milk together? I searched the Internet and found all kinds of conflicting answers. -- S.L., Moraga, Calif.

DEAR S.L.: Assuming no allergies are present, there's absolutely no problem that I am aware of. After reading your question, I did some Internet searches and found a lot of anti-soy misinformation on this matter, so I am glad you asked.

Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.

DEAR DR. BLONZ: I would like an explanation of the connection between Type 2 diabetes and obesity. After annual tests, I was told that I was a borderline diabetic. I am only slightly overweight, nothing serious at this point, but I certainly have no interest in going any further down this road. -- F.S., San Francisco

DEAR F.S.: A basic understanding of the relationship between what we eat, our blood sugar level, insulin, diabetes and body weight will serve us well. Digestion involves enzymes acting on foods to break them down into absorbable pieces. In the case of carbohydrates, it means breaking the complex carbohydrate down into its building blocks, which are primarily glucose, as a prelude to absorption. (There is no delay for carbs already in the form of glucose, sucrose or fructose.)

Once absorbed, glucose is often referred to as "blood glucose" or "blood sugar." It serves as a source of energy, but needs to get inside the cells to do its work. To gain entry, glucose requires insulin, a hormone produced and released by the pancreas in response to a rising blood glucose level. Any excess glucose will be changed into fat, the body's most concentrated form of energy, and be put away in storage in the body's fat cells.

Diabetes is present when there's insufficient insulin to get the glucose out of the bloodstream and into the cells. Type 1 diabetes is when the pancreas is unable to produce the insulin. In such cases, replacement insulin needs to be provided, usually by injection.

More common is Type 2 diabetes, which occurs when the pancreas is still able to produce and release insulin, but is unable to keep up with the demand and the blood glucose levels remain elevated. Treatments in such cases can include diet and lifestyle adjustments, or medications to stimulate the pancreas to release more insulin. Type 2 diabetes used to be known as "adult onset" diabetes because it was only seen in adults. With the increasing prevalence of childhood obesity, we now see cases of Type 2 diabetes in children.

The connection with obesity relates to the fact that, as a person gains weight, his or her fat cells increase in size. Scientists have learned that enlarged fat cells are associated with a decreased sensitivity to insulin. This "insulin resistance" means that the body needs more insulin to clear the same amount of glucose out of the bloodstream. The obesity, in essence, overworks the pancreas and eventually it is unable to keep up. Between 80 and 90 percent of those with Type 2 diabetes are obese. This also helps explain why those with Type 2 diabetes often experience dramatic improvements when they lose a few of their excess pounds.

As there can be short- and long-term complications when one's blood glucose remains elevated, the goal with any diabetic condition is to keep the glucose level within normal limits. This can be done with diet, exercise and medication, including insulin. The diet aspect involves the avoidance of eating in a way that brings about a rapid rise in your blood glucose level. Along with this goes regular blood glucose monitoring.

You appear to be at a point where monitoring and lifestyle changes can have a positive impact on your future wellbeing. I encourage you to speak with your family physician and a registered dietitian, who can help you map out strategies for weight control and food selection. It may also help to contact your local chapter of the American Diabetes Association. To find a chapter in your area, check diabetes.org.

Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.