Why does TV-watching appear to increase our risk of being overweight?

I don’t think for a moment that I’ve got my whole life sussed, and see it as a ‘work in progress’. I’ve been putting energy into my personal development and health management for 20-odd years now, and to this day still strive to lead a better, healthier, happier more balanced life. One of the most contemporary adjustments I made was to give up watching TV (other than for rugby matches). It’s difficult to describe how much I have gained by ‘losing’ television. In particular, I’ve got more time, feel less stressed, and sleep better as a result. I wrote about this, and the benefits weaning myself off my TV ‘habit’ brought here.

Another reason for not watching too much TV is that it’s associated with worth health outcomes. In particular, TV watching has been quite closely linked with an increased risk of excess weight/obesity. There has been some debate about whether this association is due to a tendency for people to snack in front of the TV, or reduced activity, or both (or perhaps other factors). I was therefore interested to read a recently published study which attempted to dissect a little what it is about TV-viewing that appears to up one’s risk of putting on weight.

This study, which appears in this months edition of American Journal of Clinical Nutrition, examined the relationship between television viewing and weight (as assessed via waist circumference) in young adults aged 26-36 [1]. In this study, individuals were assessed for a number of factors including (in addition to waist size) TV viewing time, frequency of food and drink consumption during TV viewing and physical activity levels during leisure time.

As expected, the researchers found that watching more television was associated with more in the way of waist circumference too. In particular, they found that women watching 3 or more hours of TV a day had a 89 per cent increased risk of severe abdominal obesity compared to those watching 1 hour of TV a day or less. Also, men watching 3 or more hours of TV a day were more than twice as likely to have moderate abdominal obesity compared to those watching 1 hour of TV a day or less.

Further analysis revealed that differences in leisure time activity has very little bearing on these findings. This, in my view, is not particularly surprising seeing as the evidence suggests that activity levels have relatively small influence over body weight.

Food intake during TV viewing did, however, appear to be a significant factor in the association between TV viewing and waist circumference. It did not explain all of the association, however, which suggests that other factors are at play.

So, one explanation here is that TV viewing time is a ‘marker’ for the ‘healthiness’ of someone’s life. So, it’s possible that individuals who watch less TV also, say, eat generally more healthily too. We can only speculate.

What I’d like to focus more on here is the apparent association between TV viewing and a tendency for surplus eating. One major problem here is the foods we tend to snack on while box-watching usually leave a lot to be desired from a nutritional perspective. Crappy carbs (e.g. potato chips, corn chips, pretzels, pop corn) are the order of the day here, usually. Many of these tend not to sate the appetite particularly well (which is one of the reasons some can eat enough popcorn to fill a bucket the size of their head without knowing it�), and other can be extremely ‘moreish’ (e.g. Pringles ” once you pop, you can’t stop).

Another issue is that the TV is a portal for advertisements for usually quite rubbishy foods. The influence of such adverts, even unconsciously, will not tend to encourage healthy eating, I reckon.

However, another factor here that I think has considerable relevance is the issue of ‘mindless eating’. This is, in essence, eating that we’re not really aware of (often, even when we’re not hungry). I’ve been a bit more aware of this concept recently having read a book dedicated to the subject by American psychologist Dr Brian Wansink. This witty and easy-to-read book details a myriad of influences that can lead to individuals eating more than they need to. I heartily recommend it to those of you who believe this issue may have a relevance to you or someone you know. More about this book can be found here:

References:

1. Cleland VJ, et al. Television viewing and abdominal obesity in young adults: is the association mediated by food and beverage consumption during viewing time or reduced leisure-time physical activity? Am J Clin Nutr 2008 87: 1148-1155

3 Responses to Why does TV-watching appear to increase our risk of being overweight?

  1. Anne 12 May 2008 at 8:26 pm #

    We only watch the rugby on TV too. I once worked out that the number of rugby matches we see each year must be costing us about £10 per match because of the TV licence so we’re considering getting rid of the TV entirely as it’s such a waste of that money.

    We watch plenty of Star Trek DVDs on our computer, but don’t eat while watching :-)

    Anne

  2. Paul Anderson 13 May 2008 at 9:05 am #

    Firstly, thanks for a consistently interesting blog. There is nearly always something thought prevoking and left of field.

    With regard to activity levels and weight. My understanding is that there is very little, if any, evidence to suggest that exercise is an effective means of inducing weight loss. I have never come across a study that doucments that increased activty will result in x amount of weight loss. Of course this may be because insufficent studies have been undertaken or that those that have have been poorly designed or have failed to separate out the respective contributions of diet and exercise (and other factors).

    Gary Taubes suggests that there is a tendancy to compensate for increased energy output by increasing food consumption: that exercise helps to work up an appetite. My own suspicion is that exercise is more subtle than that. Maybe its beneficial by means of improving insulin sensitivty and thereby contributing towards reducing fasting insulin levels and improved fat metabolism. I have a hunch that the exercise needs to be of sufficient duration (30 mins plus) and intensity (80% max heart rate or more) and consistency (daily) to have optimal benefit.

    The reverse may be true with regard to TV watching. The body clearly wasn’t designed to sit indoors, pretty much perfectly still, for 3 hours plus a day, staring at a TV secreen. This may well reduce insulin sensitivity. Additionally it won’t help with issues such as exposure to sunlight for vitamin D levels.

    Ironically I think one of the msot unhealthy pastimes is watching sport on TV. Watching cricket and football whlist having a few cans of beer and slices of pizza must rank among the most unhelathy ways of passing time. Far better to get and of the house and watch a game live. Admittedtly you need friends in high places with regard to the 6 nations.

    Just a few observations.

  3. Anna 13 May 2008 at 8:00 pm #

    Interesting topic; this one has been on my mind for a long time. I doubt there is any one particular factor about TV watching that is the smoking gun, but perhaps a variety of environmental factors with cumulative effects, which when added to genetic & physiological factors, make TV watching associated with negative health outcomes.

    For instance, many elderly people watch an enormous amount of TV. Elderly people often have poor health (or vice versa), are socially isolated, have high rates of depression;then again, it is a chicken or egg question? Do people stay in and isolate themselves to watch TV or do they watch TV because they stay in and isolate themselves? Do they sit and watch TV because they are physically weak, or are they weak because they sit and watch TV?

    It’s been interesting observing the changes (from afar, in the US) in my 80 yo MIL’s life the past year since she went from living very independently to moving to London and in with her unmarried mid-40s working daughter. Despite less time in solitude now, she watches a good deal more TV than she used to, and is less selective about the TV programming content (she used to primarily watch news, political talk shows, and what she considered “highbrow” drama). Now, I think the TV is on all the time she is alone (while my SIL is working) thoguh she says she is catching up on her reading now that she doesn’t have to care for a garden and house ;-). On one hand, I can see that my MIL’s social isolation increased in some ways by moving away from her very familiar medium sized academic city community to bustling London (she no longer participates in Amnesty International (though her isolation had been increasing as her elderly friends had moved or passed away in the last five years), yet she now had more daily companionship with my SIL. But my MIL’s independence rapidly decreased a great deal overall following the move, and she now spends a great deal more time alone indoors on her own, mostly watching TV. I think, despite the interesting “town-like” neighborhood, the bustle of the larger city environment is intimidating and tends to keep her in more than before. Ultimately, despite now having my SIL to cook for her and assist her, she is more rapidly becoming physically weaker and dependent from lack of movement. I’m not sure that the pace would have been as fast had she remained living independently.

    Chicken or the egg, again. Hard to blame the TV directly, but it certainly fits intimately into the picture. And of course, the thing that everyone feared, happened about year after the move; she fell getting out of bed in the night (it’s classic; she slipped in the dark on a magazine on the floor next to the bed, getting up to use the toilet), but my SIL was there to assist (hairline fracture on tibia). She’s healed well, but it was an ordeal for all involved and resulted in more sedentary days and TV shows. But I can’t help but wonder if she was more prone to the fall and injury *because* she became physically weaker, sitting more, doing less, when she no longer had to maintain so much independence. No way to know what would have happened had she remained on her own, but it’s hard not to think that perhaps some aspects, like the excessive TV watching and increased sedentariness haven’t been good, despite less worry about her being alone all the time.

    Late night TV watching also can disrupt the sleep cycles, which can really mess with health and well-being in many ways.

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