Look at children of different ages and you will immediately see the cephalocaudal principle of physical growth discussed in Chapters 2 and 3. Three-year-olds have large heads and squat, rounded bodies. As children get older, their limbs lengthen and their bodies thin out. Although from age 2 to 12 children double their height and weight, after infancy growth slows down considerably (National Health and Nutrition Examination Survey, 2004). Because they grow at similar rates, boys and girls are roughly the same size until they reach the preadolescent years.

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Now visit a playground or take out your childhood artwork to see the mass-to-specific principle—the progression from clumsy to sure, swift movements year by year. Three-year-olds have trouble making circles; third graders draw bodies and faces. At age 4, children catch a ball with both hands; by fourth grade, they may be able to hit home runs. You can see the changes from mass to specific in a few skills in Table 5.1.

Developmentalists divide physical skills into two categories. Gross motor skills refer to large muscle movements, such as running, climbing, and hopping. Fine motor skills involve small, coordinated movements, such as drawing faces and writing one’s name.

The stereotype that boys are better at gross motor abilities and girls at fine motor tasks is true—although often the differences are small. The largest sex difference in sports-related abilities occurs in throwing speed. During preschool and middle childhood, boys can typically hurl a ball much faster and farther than can girls (Geary, 1998; Thomas & French, 1985). Does this mean that girls can’t compete with boys on a Little League team? Not necessarily. The boys probably will be faster pitchers and more powerful hitters. But the female talent at connecting with the ball, which involves fine motor coordination, may even things out.

If a preschooler has precocious physical abilities, will that child be advanced at school? The answer is yes, if we look at complex fine motor skills. Researchers asked 5-year-olds to copy images and then reproduce designs displayed on another page. Performance on this more difficult test (involving fine motor coordination and the ability to judge spatial dimensions) strongly predicted elementary school math and writing skills (Carlson, Rowe, & Curby 2013).

This study suggests that to improve academic abilities we might train young children to reproduce images, in addition to teaching them numbers or how to sound out words. The problem is that pressuring (forcing) preschoolers to unwillingly perform physical tasks can be counterproductive. During early childhood, we should provide activities—such as cutting paper or scaling the monkey bars—that kids’ naturally enjoy (Zaichkowsky & Larson, 1995). Allow young children to exercise their unfolding talents, but don’t push, and provide the right person–environment fit.

Now that we’ve scanned what normally happens physically, let’s look at what can go wrong.

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I discussed the main threat to growth and motor skills in Chapter 3: lack of food. In addition to causing stunting, undernutrition impairs gross and fine motor skills because it compromises the development of the bones, muscles, and brain. Most important, when children are hungry, they are too tired to move and so don’t get the experience crucial to developing their physical skills.

During the 1980s, researchers observed how undernourished children in rural Nepal maximized their growth by cutting down on play (Anderson & Mitchell, 1984). Play does more than exercise our bodies. It can help prime neural development and is crucial in promoting social cognition, helping children learn how to get along with their peers. So, the lethargy that malnutrition produces is as detrimental to children’s relationships as it is to their bodies and brains. Notice how, after skipping just one meal, you become listless, unwilling to talk, less interested in reaching out to people in a loving way.

Keeping in mind that undernutrition remains the top-ranking twenty-first-century global physical threat, let’s now explore the condition that is ringing alarm bells in the developed world: childhood obesity.

Have you ever wondered about the source of the numbers in the charts showing the ideal weights for people of different heights? These statistics come from a regular U.S. national poll called the National Health and Nutrition Examination Study (NHANES). Since the 1960s, the federal government has literally been measuring the size of Americans by charting caloric intakes, heights, and weights. The familiar statistic researchers use to monitor overweight is body mass index (BMI)—the ratio of a person’s weight to height. If the BMI is at or over the 85 percentile for the norms in the first poll, a child is defined as “overweight.” At the 95th percentile or above, the label is “obese.”

Exploring the Epidemic’s Size

Childhood obesity ballooned about 35 years ago. During the late 1980s, the NHANES researchers were astonished to find that the fraction of obese elementary school children had doubled over a decade (see Figure 5.2). By 2012, roughly 1 out of every 6 North American children and teens was obese—four times the number in the original poll (Gordon-Larson, The, & Adair, 2010; Centers for Disease Control and Prevention [CDC], Childhood obesity facts, 2011). To bring this increase home, if you entered a second-grade classroom in the early 1970s, two children might stand out as very overweight. Eight or nine would fit that category today.

This late twentieth-century scourge has spread throughout the developed world. From Finland to France and Great Britain to Greece, governments have targeted child obesity as a public health threat (Stamatakis and others, 2010; Swinburn & de Silva-Sanigorski, 2010; Tambalis and others, 2010).

The shape of the threat, however, differs by nation. Obesity rates are lower in Scandinavia than in Mediterranean countries and the United States (Faeh & Bopp, 2010). In the developing world, childhood obesity is most common in cities and among affluent boys and girls (Berkowitz & Stunkard, 2002). In the United States, obesity rates are higher in rural areas (Davis and others, 2011), and far more common among the poor. There is also an ethnic dimension to the epidemic. Obesity is most prevalent among Latino and African American boys and girls (Boonpleng and others, 2013).

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The great news is that in recent years, the prevalence of preschool obesity declined significantly, from roughly 14 percent in 2003–2004 to 8.4 percent in 2011–2012. The bad news is that this condition is still so common throughout the childhood years (CDC, Childhood obesity facts, 2012). Why, despite vigorous attention, is obesity resistant to change?

Exploring the Epidemic’s Wider-World Roots

The reason lies in a perfect storm of societal “obesogenic” forces (Finegood, Merth, & Rutter, 2010; Swinburn & deSilva-Sanigorski, 2010): stressed out working parents who don’t have time to prepare nutritious, sit-down meals (Morrissey, Dunifon, & Kalil, 2011); expanding restaurant portion sizes; and easy access to low-cost calorie-dense foods—such as chips and sugar-laced sodas tailored to tempt the palates of children (and adults) (Cornwell & McAlister, 2011).

Lack of exercise plays an important role. With the Internet and TV, playing outside—that typical childhood vehicle for burning up calories—has sharply declined. Obese children, being less physically active than their normal-weight peers, lag behind in gross motor abilities (Soric & Misigoj-Durakovic, 2010). There may be a poisonous bidirectional effect here. When children feel bad about their “big clumsy bodies,” they withdraw from physical activity, watch more TV, and snack more.

To tackle the weight of obesity-promoting forces, governments have developed a host of policies, from requiring school cafeterias to limit fattening foods, to mandating calorie counts for sodas and Big Macs. Still, societal efforts have been less than effective, partly because individuals vary greatly in the tendency to pack on pounds. When researchers tracked thousands of preschoolers, they found that, yes, the school and neighborhood fast-food milieu played some role; but the primary predictor of a child’s kindergarten “weight status” was his mother’s weight (Boonpleng and others, 2013).

It’s tempting to see this striking correlation (overweight parents have overweight children) and conclude that obesity is genetic, so there is nothing we can do. Or perhaps you (like many of us) have mentally accused overweight parents for loading themselves and their kids up with fattening foods.

Exploring the Epidemic’s Epigenetics

Tantalizing research suggests obesity has a partly epigenetic, pre-birth root. Women who gain excessive weight during pregnancy, and so give birth to large babies, are at higher risk of having an obese child (Boonpleng and others, 2013). Recall from Chapter 2 that being born premature and excessively small may also “turn on” the biological tendency to overeat and store fat. Therefore, events in the womb and at birth might set us up to pack on pounds by literally changing our DNA.

Interestingly, scientists can predict this predisposition soon after we emerge from the womb. Rapid weight gain during infancy and early childhood is a strong predictor of later obesity—outweighing even a child’s genetic propensity to gain weight (Belsky, 2013; Belsky, Moffitt, & Caspi, 2013). So what happens during our earliest years can biologically set us up to battle obesity for life (see Belsky, 2014, for review).

Exploring the Epidemic’s Consequences

This lifelong battle takes a social toll. From being less likely to get hired (Puhl & Heuer, 2010) or finish college (Fowler-Brown and others, 2010) to having problems getting elected to public office (Miller & Lundgren, 2010), obesity can present serious barriers to living a successful life.

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These barriers begin soon after babyhood (Puhl & Latner, 2007). In a classic study, elementary schoolers were shown pictures of an overweight child, a child in a wheelchair, another with facial disfigurements, and several others with disabilities. When asked, “Whom would you choose as a friend?” the children ranked the obese boy or girl last. By age 3, children describe chubby boys and girls as “mean” and “sloppy.” So it’s no wonder that, in the West, overweight children are at risk of suffering from depression in their teens (Pitrou and others, 2010; Sánchez-Villegas and others, 2010).

Attitudes are less harsh in other cultures. In Bangladesh, obesity actually promotes high self-worth (Asghar and others, 2010). There are differences by ethnicity, with African Americans more weight tolerant than their Caucasian counterparts (more about this in Chapter 8). And of course, there are variations from family to family. Parents who care vitally about physical beauty hold especially negative stereotypes about overweight people, and are prone to monitor a child’s every bite (Puhl & Latner, 2007).

This pressure can backfire (no surprise), producing binge eating (Matton and others, 2013), compounding an elementary schooler’s already fragile self-esteem. Therefore, many parents go in the opposite direction. They minimize weight issues in their child (Luttikhuis, Stolk, & Sauer, 2010). “My daughter may be chubby, but she’s perfectly fine.” Ironically, then, in one study, the very people who could most benefit from an obesity prevention program—mothers with overweight preschoolers—were least likely to enroll (Taveras and others, 2011).

Let’s understand where these adults are coming from. Faced with the prejudices their children are already enduring, parents want to protect their sons and daughters from further pain. As one woman reported, “He’s a highly sensitive child, and he’s got very low self-esteem generally . . . I think, (if he participated in the program) . . . he would . . . think, ‘what’s wrong with me?’” (quoted in Barratt and others, 2013, p. 61).

Moreover—perhaps because by age 4 or 5, obesity is more resistant to change— family-focused weight-control programs, even when they show initial success (Sung-Chan and others, 2013) often don’t work in the long term. Plus, once a boy or girl moves out of the family orbit, friends’ eating practices make a huge difference in that child’s food choices (Hemar-Nicolas and others, 2013).

Question 5.4

Long-distance running and the high jump would be ideal for Jessica, as these sports heavily tap into gross motor skills.

Question 5.5

The prevalence of obesity is declining during preschool.

Question 5.6

All of these forces predict later overweight.

Question 5.7

The best age to intervene to prevent obesity is birth age 1.

Question 5.8

Because parents—especially those with an overweight child—might be unwilling to participate to protect their own and their child’s self-esteem, empower families by having them plan the intervention strategies.