DEAR DR. BLONZ: I am a 25-year-old, 6-foot-2, 164-pound man. I am writing because of what I consider to be a racing metabolism, as I have been wanting to put on a bit of flesh to fill what is typically described by friends as my “drawn face.” What kind of foods can I eat so that my body will start to fill out, but do so in a healthy way? -- G.J., Seattle, Washington

DEAR G.J.: While most might consider obesity as the only problem associated with body weight, many, like yourself, cannot fill out their form as they would prefer. Several factors can contribute to the “racing metabolism” you describe, but this is definitely a topic to be raised with your health professional. A contributing factor could be if one or both of your parents are also slim, as that body type may be your genetic legacy. There are also possible medical/hormonal reasons for excess thinness, which is another reason to raise this with your physician before you turn to diet, supplements or exercise for answers.

Assuming there are no health issues to consider, and you get the go-ahead, adding calories in a way that’s healthful and with foods you will enjoy is key. Several calorie-concentrated milkshake products are in the market. These products contain hundreds of calories, and if taken in addition to your regular diet, will help you gain weight. Go slowly to allow your body to adapt to this regimen change.

A weight-training program is another consideration. Although the thought of exercise may run contrary to the idea of losing weight, the bulking up experienced by lifters could give you some say over how your form fills out. Also, remember to stay well hydrated, an important element for any healthy weight.

For a general discussion of body weight, see b.link/avgk54y. For suggestions for some healthful, high-calorie snacks, see b.link/nj5bd7r.

DEAR DR. BLONZ: My neighbor grilled fish recently, and it was a great meal. Leftovers were put in containers to go into the freezer, but they were inadvertently left on the counter overnight. The next morning, as soon as it was discovered, she put them in the freezer. She told me that freezing would kill any bacteria that might have grown during the night. She wouldn’t believe me when I told her that was not a good idea and that she or her family could get sick from eating these leftovers. She said she can defrost and cook them in the microwave. Is this a safe practice? Does freezing kill bacteria? Not to mention what it might taste like. -- C.A., Chicago, Illinois

DEAR C.A.: Freezing suspends growth but does not kill bacteria in this situation. When a food defrosts, microbial growth picks up where it left off on the counter. Eating foods left out in the way you describe represents a roll of the food-safety dice. There’s no safety guarantee even if you were to pay special attention to cooking the food thoroughly after being defrosted. In my opinion, the safest course is to toss the stuff. For more on the food safety temperatures, see b.link/22gnu9n.

Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 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 am concerned about the mineral zinc and whether it is possible to get too much. The multivitamin and mineral supplement I use each contain 100% of the daily zinc requirement. I want to know if this could be a problem. -- F.F., Scottsdale, Arizona

DEAR F.F.: Zinc, like many essential nutrients, is involved in an impressive variety of bodily functions. Not only is zinc integral to a key enzyme in our immune system (glutathione peroxidase), but it also plays a role in our skin, hair, our sense of taste, proper calcification of the bones, and the development and operation of the sexual organs. Additionally, zinc is in several enzyme systems related to digestion, and, finally, zinc plays a role in the normal functioning of insulin -- the hormone that regulates the blood's sugar level.

An informative study in the Journal of the American Medical Association looked at 589 pregnant women with low zinc levels in their blood. Half the women in the study received 25 mg of a zinc supplement daily during pregnancy. The study found that supplementation improved their pregnancy outcomes by significantly increasing birth weight.

It is possible to get too much zinc, but the chance for toxicity is remote if your only source is the zinc in your diet. When taking it as a supplement, it's prudent not to take more than 40 mg a day unless specifically requested by your health professional. (For more on zinc's benefits, see b.link/eexcawg.)

DEAR DR. BLONZ: Often, when having sugarless gum or mints, I end up with cramps, or "the runs." My friend says I could be allergic to the artificial sweetener sorbitol. I doubt this because sometimes I can enjoy sugarless mints with no side effects. I want to be able to continue enjoying them. -- L.H., Richmond, California

DEAR L.H.: Sorbitol is not an artificial sweetener, because it occurs naturally in many fruits. However, while an allergy could be the issue, sorbitol would be a prime suspect for your G.I. discomforts. Sorbitol is a "sugarless sweetener" because it has a sweet taste -- about half as sweet as table sugar -- but doesn't promote tooth decay, and it's not absorbed from the digestive tract like other sugars.

The downside to sorbitol is that it attracts and holds water in the digestive tract, which can lead to diarrhea in some people. In addition, many bacterial flora in the large intestines can digest sorbitol, which release gas as their waste product, with obvious results. Small amounts of sorbitol may pass through without discernible symptoms. In larger quantities, as with several mints or sticks of sugarless gum -- particularly on an empty stomach -- the upset you described can result.

Anyone with problems using sorbitol or a similar synthetic sweetener, xylitol, should limit their intake or consume it only after a meal to slow its passage through the digestive system. (For more on sorbitol, see b.link/bcc7y84.)

Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 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: Why is it best to get vitamins from food rather than from supplements? Does the human body make the distinction, and if so, to what extent? -- R.S., Boston

DEAR R.S.: A vitamin is the same whether it comes from food or from a synthetic formula. To the human body, it's a chemical that fills a need. My response would be different if you had asked whether getting nutrients from whole foods is better.

We now has effective methods to diagnose nutrition deficiencies, and much of this data comes from population studies. However, science has only begun to investigate how certain health or genetic issues might affect what is best for a particular individual. Interactions with medications, and even between nutrients and herbs, must be considered. (For more on drug interactions with supplements and herbs, see b.link/ejz74zb.)

Modern science has come a long way, but we are far from knowing all there is to know. The human body may not be able to distinguish between a particular nutrient from food versus the identical substance provided as a supplement, but nature's whole foods typically contain complementary substances that help the nutrient do its job most effectively. Thus, it is always best to get the entire team, which comes from a nutrient in its whole-food context.

DEAR DR. BLONZ: I work to have a whole-food diet, as you recommend. Still, when I recently purchased vitamin and mineral supplements, I noticed that my mineral supplement contains calcium amino acid chelate, and my vitamin supplement contains D-calcium pantothenate. Why is this calcium compound in my vitamin? I have read that too much calcium can be toxic, so I want to ensure that I'm not taking too much calcium if both products provide similar ingredients. -- S.T., Dover, Delaware

DEAR S.T.: In the same way that its chemical name, ascorbic acid, also refers to vitamin C, the compound known as vitamin B5 can go by its chemical name, pantothenic acid.

The calcium in D-calcium pantothenate is indeed an essential mineral, but it would be best to think of it as a "salt" of pantothenic acid made from two molecules of the pantothenic acid joined with one calcium molecule. When dissolved, the calcium and the pantothenic acid go their separate ways, leaving the B5 to be available as the vitamin. The amount of calcium is negligible.

To illustrate: Say you took the adult daily value of pantothenic acid (5 milligrams) as D-calcium pantothenate. This would add less than one-half of one milligram of calcium to your daily total for this mineral, which has an adult daily value of 1,000 mg. Anything, including calcium, can become toxic if taken in excess. However, there is no issue here.

Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 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.