Just One Hour of This Daily Can Make You Obese

Watching Television

Story at-a-glance

  • Children who watched just one hour of TV daily were more likely to be overweight or obese
  • One hour of daily TV is linked to a 60 percent greater risk of overweight and a 73 percent greater risk of obesity
  • The average US kindergartner watches more than three hours of TV a day


This is an older article that may not reflect Dr. Mercola’s current view on this topic. Use our search engine to find Dr. Mercola’s latest position on any health topic.

By Dr. Mercola

In the US, more than one-third of children and adolescents are overweight or obese. Physical inactivity, and particularly watching TV, which exposes children to junk-food commercials and presents a prime opportunity for unhealthy snacking, is known to increase this risk.

Nearly 20 years ago, a study by researchers at Johns Hopkins University School of Medicine, along with experts at the US Centers for Disease Control and Prevention (CDC) and the National Institutes of Health, concluded that a child's weight increases with the number of hours he or she spends watching television each day.

This isn’t entirely surprising, but a new study presented at the Pediatric Academic Societies’ (PAS) annual meeting in San Diego in April 2015 revealed a finding that is… watching just one hour of TV a day may be enough to lead to an unhealthy weight.

One Hour of TV a Day Linked to Overweight and Obesity

Using data from more than 11,000 children, researchers from the University of Virginia found kindergartners and first graders who watched just one hour of TV daily were more likely to be overweight or obese than children who watched less.1

The association was strong, with one hour of daily TV linked to a 60 percent greater risk of becoming overweight and a 73 percent greater likelihood of obesity. Computer use was not associated with higher weight, perhaps because, despite being a sedentary activity, it doesn’t expose children to as many junk-food advertisements and is less conducive to snacking.

While the American Academy of Pediatrics suggests children and teens spend no more than two hours daily engaged in screen time, the average US kindergartner watches more than three hours of TV a day. Dr. Mark D. DeBoer, an associate professor of Pediatrics in the Division of Pediatric Endocrinology at the University of Virginia and author of the study, told Fox News:2

We hope that the American Association of Pediatrics consider reducing its allowed TV viewing to one hour daily for young children and recommend that parents replace their children's TV viewing time with opportunities for physical activity and educational activities.”

Keep the TV Out of Your Child’s Bedroom

One basic way to help limit the amount of TV your child watches is to keep the TV out of his or her bedroom. In a survey of more than 3,000 fifth graders, half of the children said they had either a television, DVD player, or video game in their rooms.3

More than half (57 percent) of them said they would use these devices even after they were supposed to be asleep, for instance staying up later to watch TV in bed. As you might suspect, those who had access to electronic devices generally slept less, and shorter sleep duration is linked to obesity.

Getting just one extra hour of sleep a night was linked to a 28 percent lower risk of being overweight and a 30 percent lower risk of being obese, according to the study. On the other hand, kids who used electronic devices at bedtime were nearly 1.5 times more likely to be overweight.

Among those who had three or more such devices in their bedroom (such as a TV, computer, and video games), the risk jumped to over 2.5 times. When you’re sleep deprived, your body decreases production of leptin, the hormone that tells your brain there is no need for more food. At the same time it increases levels of ghrelin, a hormone that triggers hunger.

In addition, sleep-deprived people tend to eat more sweet and starchy foods rather than vegetables and dairy products. Researchers suspect these cravings stem from the fact that your brain is fueled by glucose (blood sugar); therefore, when lack of sleep occurs, your brain searches for carbohydrates.

In short, sleep deprivation puts your body into a pre-diabetic state, and makes you feel hungry, even if you've already eaten. Encouraging less sleep is just one way that TV watching may contribute to weight gain…

Artificial Light from TV May Promote Weight Gain

When you turn on a light at night, you immediately send your brain misinformation about the light-dark cycle. The only thing your brain interprets light to be is day. Believing daytime has arrived, your biological clock instructs your pineal gland to immediately cease its production of the hormone melatonin.

Whether you have the light on for an hour or for just a second, the effect is the same — and your melatonin pump doesn't turn back on when you flip the light back off. Melatonin appears to improve weight control by increasing “beige” fat, which is a heat-generating type of fat that helps your body to burn calories rather than store them. If you’re regularly exposed to light at night, including from a television or computer, you’re missing out on this fat-burning potential.

In one study, mice that were exposed to dim light during the night gained 50 percent more weight over an eight-week period than mice kept in complete darkness at night.4

They also had increased levels of glucose intolerance, a marker for pre-diabetes. The weight gain occurred even though the mice were fed the same amount of food and had similar activity levels, and the researchers believe the findings may hold true for humans as well.

Separate research also found mice exposed to longer periods of light gained fat because their brown fat wasn’t working as efficiently.5 Like beige fat, brown fat is a heat-generating type of fat that burns energy instead of storing it, which explains its role in proper weight management. In the mice exposed to excess light, however, the brown fat converted fatty acids and glucose to heat more slowly than usual.6

Junk Food Marketers Are Targeting Your Kids

According to a 2013 report by the Institute of Medicine (IOM),7 children age 2 to 11 see an average of more than 10 television food ads per day. And nearly all (98 percent) of these are for products that are high in processed, damaged fats, sugar, and/or sodium. Most (79 percent) are low in fiber.8 According to the IOM:

"The marketing of high-calorie, low-nutrient foods and beverages is linked to overweight and obesity. A 2006 IOM report provided evidence that television advertising influences the food and beverage preferences, requests, and short-term consumption of children."

In the wake of rising rates of childhood obesity and other chronic conditions that are undoubtedly linked to poor diets – high blood pressure, type 2 diabetes, certain behavioral problems, and so on – intentionally trying to hook kids on junk foods might be considered a crime or certainly immoral.

At the very least, it’s clearly on par with what the tobacco industry did for decades, hooking young kids on their addictive and lethal products before they were even old enough to know better. It’s an instance where increased regulatory action might have been beneficial, and in fact was beneficial – before the protections were taken away.

In the late 1970s, the US Federal Trade Commission (FTC) tried to ban all ads aimed at kids below the age of 8. But then industry stepped in and convinced Congress to block such attempts. Instead of banning advertising to children, Congress passed “The FTC Improvement Act,” which stripped the FTC of the power and authority to regulate marketing to children.

The final blow came in 1984, when the entire industry was deregulated. Before deregulating children’s TV marketing, children’s spending had risen at a modest 4 percent per year.

After deregulation, children’s spending skyrocketed to 35 percent per year, from $4.2 billion a year in 1984 to $40 billion a year in 2013—an 852 percent increase in less than three decades. Combining junk food with TV is a particularly deadly combo, as you’ve got two culprits of weight gain and disease: inactivity and sugar.

Sugar Blamed for Obesity Epidemic

While there are a myriad of reasons why children shouldn’t be watching much TV, it’s important to note that an abundance of junk food and sugary beverages is probably an even greater factor in weight gain than TV.

Writing in the British Journal of Sports Medicine, researchers stated it’s time to “bust the myth of physical inactivity and obesity.” While rates of obesity have risen sharply over the last three decades, rates of physical activity have stayed largely the same.9

The culprit, they say, is a poor diet loaded with excess sugar and carbohydrates. The review noted that poor diet is responsible for more cases of disease than physical inactivity, alcohol, and smoking combined.10 The review also blasted the food industry, which they argue is using marketing tactics that are “chillingly similar” to the tobacco industry. As reported in the Telegraph:11

The ‘false perception’ that exercise matters more than healthy eating is due to how the food industry is marketed… They use the example of Coca-Cola associating its products with sport, ‘suggesting it is OK to consume their drinks as long as you exercise.’

They claim the public health messaging around diet and exercise, and their relationship to the epidemics of type 2 diabetes and obesity, has been corrupted by ‘vested interests.’ Celebrity endorsements of sugary drinks and the association of junk food and sport must end, they said.”

The study pointed out some revealing statistics, such as for every excess 150 calories of sugar there was an 11-fold increase in type 2 diabetes compared to 150 calories consumed from fat or protein – independent of a person’s weight and physical activity level. Meanwhile, lead author Dr. Aseem Malhotra, a cardiologist at Frimley Park Hospital in Surrey, told the Telegraph:12

Cutting down on carbs was also found to be the single most effective intervention for reducing all the features of the metabolic syndrome and should be the first approach in diabetes management, with benefits occurring even without weight loss, he said. Instead, fat appears to be the ideal fuel for most exercise.”

Beyond Obesity: Why Kids Shouldn’t Watch Much TV

The fact that sugar may play an even greater role in obesity than physical inactivity is certainly not a carte blanche to watch as much TV as you want. Even among adults, research has shown watching more than 14 hours of TV per week was associated with an increased risk of insulin resistance, obesity, and high cholesterol in both men and women.13

In children, however, TV is especially damaging. For instance, in a study of children aged 3 to 9 years, kids with TVs in their bedrooms, and those exposed to more background TV, performed more poorly on theory-of-mind assessments.14 That is, they had a lower understanding of different mental states, including other people’s beliefs and desires.

A 2015 study that examined sleep patterns and mental health among 1,000 children also found that those with sleep disorders at age 4 were more likely to have mental health problems, including anxiety and depression, at age 6.15 In addition, Dr. Aric Sigman, a British psychologist, analyzed 35 different scientific studies on television and its effect on the viewer.16 He found it produces an almost narcotic effect on your brain, actually numbing areas that would be stimulated by other activities, like reading. Dr. Sigman has identified 15 negative effects that he believes can be blamed on watching television, stating:

“Watching television, irrespective of the content, is increasingly associated with unfavorable biological and cognitive changes. These alterations occur at viewing levels far below the population norm. Given the population’s sheer exposure time to this environmental factor it is more than puzzling to consider how little awareness and action has resulted.”

The risks Dr. Sigman revealed include:

Obesity Delayed healing Heart trouble Decreased metabolism Damaged eyesight
Alzheimer's disease Decreased attention span Hormone disturbances Cancer Early puberty
Autism Sleep difficulties Increased appetite Limited brain growth Diabetes

Tips for Helping Kids Maintain a Healthy Weight

Helping children lose weight, or maintain a healthy weight, typically takes a comprehensive lifestyle shift, just as it often does with adults. You can start by cutting back on TV. According to Dr. Sigman and other experts, children under age 3 should watch no TV at all, while those ages 3-7 should watch no more than 1.5 hours a day. For older kids, two hours of TV and/or computer/video game use should be the daily limit. You may choose to watch less than this, of course, but ideally not more.

Meanwhile, encourage your kids to be active. Organized sports, dance, swimming lessons, martial arts, and free play outdoors are all ways to keep your kids moving instead of being sedentary. You might start an after-dinner tradition of taking a walk as a family, or walk to and from school with your child, to fit in more daily movement. Next, eliminating excess sugar and fructose will also be important. Children can easily cut down on the amount of sugar they eat by eliminating soda and juice and only drinking water.

This step alone can have a dramatic affect on your child’s weight and health, since every daily soft drink or sugar-sweetened beverage consumed increases the risk of obesity by a whopping 60 percent. It’s important for parents to encourage their children to eat healthy, nutritious foods, focusing on fresh whole foods (preferably organic whenever possible).

You should allow your child to eat when he’s hungry, however. Children need calories and nutrients to grow and develop -- just make sure to encourage healthy foods and bypass junk and processed foods. You can find even more help in the book I wrote on the subject, Generation XL: Raising Healthy, Intelligent Kids in a High-Tech, Junk-Food World. In addition, here are six more tips to foster a healthy view of food and self-esteem in your child.

Lead by example and seek to maintain optimal body weight for yourself and your spouse Refrain from making jokes about your child’s weight, even if no harm is intended
Explain the health risks of being overweight to your child, but avoid comparing your overweight child to other children, including thinner siblings Cook healthy meals for your family, and let your child be involved in making dinner; avoid making your child eat different food than the rest of the family
Encourage your children to make healthy food choices and praise them when they do instead of putting your child down about weight or eating habits Instead of using food as a reward or punishment, have healthy snacks available at all times, and explain to your child the benefits they’ll get from eating these fresh, whole foods; use non-food items, such as stickers or special outings/activities as rewards instead


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