Visual Obesity Villains: Light and Heaviness

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In regard to the worldwide obesity epidemic, Dr. Pretlow has referred to the concatenation of events and influences as the “perfect storm,” a term borrowed from meteorology that refers to large-scale synergy. It is what happens when a number of elements come together that, separately, might have been merely bad but not catastrophic. In combination, however, the various influences combine their forces to wreak havoc. Childhood Obesity News published an overview of many of these larger forces in an 8-part series. Some, like the widespread presence of high fructose corn syrup in processed foods and sweet drinks, seem obvious.

Another large and obvious problem is the increasingly sedentary lifestyle practiced by almost everyone on earth. Physical exertion burns calories of course, but as Dr. Colin Higgs noted, along with maintaining a healthy weight there are 14 other benefits to be obtained from exercise – all of which can contribute indirectly to that healthy weight goal.

Those are only two of several mega-causes, and there are also random less extensive ones. Over the past couple of weeks we have looked at a large number of factors claimed by someone, somewhere, to contribute to the epidemic. These items are presented as information, and are not necessarily endorsed. Some seem far-fetched, even silly. Other detrimental factors affect only a small segment of the population. Astonishingly, our survey of possible obesity villains is not yet complete.

Artificial light

Artificial light includes everything that isn’t the sun: interior and exterior electric lighting, tablets and other computer monitors, mobile phones, and television screens. Such light has biological effects described as “acute.” The intensity and duration of the light, and the time of day at which it is experienced, all are significant. Animal experiments had already shown that metabolic function and body weight are influenced by artificial light.

The world total of obese children is said to now be 42 million, a mind-boggling number that translates into a mountain of financial expense and an unimaginable amount of human misery. In Australia, the Queensland University of Technology did some research on the link between artificial light and body weight. The results were published by the journal PLOS ONE. PhD candidate Cassandra Pattinson and colleagues obtained information about children ages 3 to 5 from several preschool childcare centers in Brisbane. They started (Time 1) by measuring each child’s height and weight, then observed their sleep patterns, activity levels, and light exposure for two weeks. Pattinson is quoted as saying,

The circadian clock – also known as the internal body clock – is largely driven by our exposure to light and the timing of when that happens. It impacts on sleep patterns, weight gain or loss, hormonal changes and our mood… At time 1, we found moderate intensity light exposure earlier in the day was associated with increased body mass index (BMI) while children who received their biggest dose of light – outdoors and indoors – in the afternoon were slimmer.

Returning a year later, they re-measured everything and arrived at their conclusions. The kids whose total light exposure at Time 1 had been greater had higher BMI scores. A parenting “best practice” is to provide a bedroom with no television, computer, or smartphone in it. The consensus is that children need to go to sleep earlier, sleep later, and in general reduce their time spent with electronic screens.

Heavy servers

As if ill-timed exposure to light were not bad enough, it is also suggested that damage can be caused by the sight of overweight waiters and waitresses. It sounds like the basis for a comedy sketch, but the results of a study performed by Cornell University’s Food and Brand Lab were published in the professional journal Environment and Behavior.

Researchers looked at 497 diners in 60 casual restaurants. They found that those served by heavier waiters or waitresses were four times more likely to have dessert and to consume 17 percent more alcohol… The researchers also found that the apparent effect heavy servers had on customers’ ordering was strongest on the skinniest diners.

A mitigating tip offered by the study authors is to make the decision ahead of time to either order an appetizer or dessert, but never both.

Your responses and feedback are welcome!

Source: “Global research hub publishes QUT study on light exposure and kids’ weight,”, 10/07/16
Source: “Heavy waiters, waitresses may prompt bigger orders,”, 01/12/16
Image by Marta Diarra


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OVERWEIGHT: What Kids Say explores the obesity problem from the often-overlooked perspective of children struggling with being overweight.

About Dr. Robert A. Pretlow

Dr. Robert A. Pretlow is a pediatrician and childhood obesity specialist. He has been researching and spreading awareness on the childhood obesity epidemic in the US for more than a decade.
You can contact Dr. Pretlow at:


Dr. Pretlow’s invited presentation at the American Society of Animal Science 2020 Conference
What’s Causing Obesity in Companion Animals and What Can We Do About It

Dr. Pretlow’s invited presentation at the World Obesity Federation 2019 Conference:
Food/Eating Addiction and the Displacement Mechanism

Dr. Pretlow’s Multi-Center Clinical Trial Kick-off Speech 2018:
Obesity: Tackling the Root Cause

Dr. Pretlow’s 2017 Workshop on
Treatment of Obesity Using the Addiction Model

Dr. Pretlow’s invited presentation for
TEC and UNC 2016

Dr. Pretlow’s invited presentation at the 2015 Obesity Summit in London, UK.

Dr. Pretlow’s invited keynote at the 2014 European Childhood Obesity Group Congress in Salzburg, Austria.

Dr. Pretlow’s presentation at the 2013 European Congress on Obesity in Liverpool, UK.

Dr. Pretlow’s presentation at the 2011 International Conference on Childhood Obesity in Lisbon, Portugal.

Dr. Pretlow’s presentation at the 2010 Uniting Against Childhood Obesity Conference in Houston, TX.

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