DEAR DR. BLONZ: Our only child just turned 13. He continues to grow, but there is a bit more of him than we would like. Our doctor has mentioned that he is in the upper percentiles for his age, but did not seem overly concerned after a recent visit.

There is no obesity in the family; my husband and I have a few extra pounds here and there, but we eat well and go for walks most days. Our son is active and eats pretty well, but spends a bit more time online than most in his circle. When pressed, he admits to being aware of the issue, but shows little motivation to make changes. -- Anonymous, via email

DEAR ANONYMOUS: In general, it's best to avoid excess weight than face the challenge of taking it off after it's become a long-term resident. At the same time, it is not uncommon for children to go through periods where they carry a little extra weight; these often precede an impending growth spurt and are not necessarily indicative of long-term problems.

That said, childhood obesity remains a problem in this country, affecting about 1 in 5 children aged 2 to 19. This means more children are setting a course toward heart disease, diabetes, hypertension, cancer and other chronic health problems that can plague them as adults. (See the Center For Disease Control and Prevention's "Childhood Obesity Facts" page at b.link/nqr37x.)

There can be genetic factors, but that's not the sole cause. Activity patterns and food choices are key. For those in their early years, it's essential to keep track of time spent being physically active versus that spent online with social media, gaming and television. An informative study in the journal Pediatrics reported that a child's metabolic rate, the rate at which the body burns calories, tends to slow when the child is planted in front of a screen. Surprisingly, this rate decrease was significantly larger than the normal metabolic slowdown observed during rest.

Online activities -- social media, app-based video games, etc. -- can be mentally stimulating, but tend to be physically passive. Purveyors of these activities devise clever ways to push ads and links using language, music and graphics tailored to their young audience. Likewise, the food industry has an expansive children's market; one need only look up and down the aisles at the market to see which items are purposefully placed at kids-eye level. Fast-food restaurants, of course, have long offered kid-focused freebies.

Bribing children to "eat their vegetables" or "clean their plates" using treats or computer time as a reward can distort the value of healthful eating. A family strategy might be considered that includes "budgets" for various types of food, online time and physical activities.

Design goals and rewards tailored for each individual, plus some rewards that will appeal to all. Whether it's a desired family trip, a large purchase or special family activity, work out the details together, ensuring everyone follows the same rules. The idea is to set up a win-win situation with pride of accomplishment along the road to better health.

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 eat lots of fruits and vegetables, and go with organic produce whenever possible. But increasing food costs are making this difficult. I have a good relationship with the head of the produce department at my grocery store, and she assures me that while the store is part of a chain, they source locally whenever possible, and only from places that are conservative with their use of agricultural chemicals.

She also mentioned IPM as a backup to organic. I understand that conventional produce is not dangerous, but how does IPM fit in? My concern is that some cumulative risk will emerge down the road. -- J.T., Tulsa, Oklahoma

DEAR J.T.: The hazards from pesticides are well behind other dangers in our food supply, such as mishandling, bacterial contamination and the presence of naturally occurring toxins. In other words, the most significant risks in our foods are placed there by nature, not technology.

There is no practical way of measuring how, or if, an amount of residue deemed safe today might affect your health down the road. But researchers, and those involved with consumer protection, keep studying the issues to stay on top of emerging science. One problem is that we cannot judge the effects of residues' interaction with each other or what happens when pesticide exposures occur in conjunction with health problems, medications and other unknown stressors the body is coping with. That may be why, despite assurances, survey after survey reveals that consumers like yourself continue to be wary of produce that is not organic.

A critical takeaway here: There is little question that it's better to eat conventionally grown produce than to cut back on these healthful foods because you can't afford organic. The produce market is not a hazardous place where we need to fear every bite. At the same time, this does not justify blind support for unnecessary synthetic pesticides, herbicides and fungicides. We should always eat as though our life depends on it, but also must be aware of the environmental impact of our food choices.

My compliments to your produce manager for mentioning IPM, which stands for integrated pest management. This approach limits the use of synthetic chemicals whenever possible, although they remain in a farmer's toolbox to be called upon when needed. For more on IPM, check the EPA's page at b.link/pskb1n. And here is a list of regional IPM Centers: b.link/j7ppwz. Stores typically mark which items are organically grown; it would be helpful if they would also label the foods from farmers using IPM. A poster explaining this alternative would be a teachable moment and help customers express their preferences.

Other steps to minimize any risks from produce: Wash your fruits and vegetables, and buy produce grown locally or regionally. Shop at farmers markets when possible. Consider focusing on fruits and vegetables that are in season where you live, as those grown in other countries might not be held to the same level of scrutiny.

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 READERS: Often, the letters I receive reflect the rise in diet and health advice found online and through social media. While I welcome the increase in helpful, evidence-based information, it has, unfortunately, been rivaled by skillfully marketed stuff best described as "wacky."

Reasonable consumers must therefore take on the chore of sorting the science-based information from the worthless -- and sometimes dangerous -- cyber junk. Here are some of my "rules of the road" when looking for answers online.

-- Seek objective, evidence-based confirmation for the safety and efficacy of any health-related product, treatment or dietary supplement. The accepted standard: competent, reliable scientific evidence published in a reputable, peer-review journal. Websites that end in ".edu" (educational institutions) and ".gov" (government resources) are reasonable places to start.

-- To support a concept, there should be at least two clinical studies (that is, studies using people) done by independent teams, ideally teams that have no association with the product being tested. It is entirely reasonable that a company with a financial interest in a product would fund research about it, but exercise caution if that company's research is the only support out there.

-- Clinical research using subjects with various states of disease can offer insight into mechanisms relating to that condition. Still, it cannot be assumed that the same effects will occur in otherwise healthy, well-nourished individuals (unless that study has also been done). For example, an individual can feel sluggish if they have iron-deficiency anemia, and replenishing their required iron will increase their energy. From this finding, however, you cannot claim that an individual who is not iron-deficient to begin with will experience similarly increased energy if taking the same supplement.

-- Studies should undergo peer review before publication. This is a process where experts in the field, selected by the journal, examine the details of the work. The journal editor has the last word on whether the study is accepted as-is, accepted after making specific revisions, or rejected. Reputable journals should also reveal any conflicts of interest relevant to the studies they publish -- for instance, whether the authors have any financial interest in the success of the product or technique.

-- It is also essential to check whether the study used the precise substance and dose as that found in the product.

-- Many products use customer testimonials; these are designed to be seductive and to sound convincing, as are social medial videos! Testimonials should not be the sole reason you decide to buy a product. Don't be persuaded when the only available "positive" information comes from entities vested in the product's sale.

-- The concept of "They couldn't say that if it wasn't true" is misleading. There are a variety of ways by which health products get promoted; regulatory agencies cannot be expected to keep up with the ever-changing frontier of false, illegal and questionable claims.

-- Finally, be aware that the ingredients in health products and supplements can interact with each other and with prescription medications. Be upfront about what you take with any health professional entrusted with your care.

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.