So, as Michelle Obama yesterday announced her childhood obesity initiative, another piece of news on childhood obesity crowded the news wires.

This was a study by Sarah Anderson (Ohio State) and Robert Whitaker (Temple) published as an early release in Pediatrics.

The researchers performed a cross-sectional analysis of a nationally representative sample of 8550 four-year-old US children who were assessed in 2005 in the Early Childhood Longitudinal Study.

The study focussed on the relationship between obesity and three household routines: regularly eating the evening meal as a family (>5 nights per week); obtaining adequate nighttime sleep on weekdays (10.5 hours per night); and having limited screen-viewing (television, video, digital video disk) time on weekdays (2 hours/day).

Analyses were adjusted for the child’s race/ethnicity, maternal obesity, maternal education, household income, and living in a single-parent household.

While the prevalence of obesity was 14.3% among children exposed to all 3 routines (14.5% of the sample), it was 24.5% among those exposed to none of the routines (12.4%).

The odds of obesity associated with exposure to all 3, any 2, or only 1 routine (compared with none) were 0.63, 0.64, and 0.84, respectively.

So if you do have kids ask yourself:

1) Do we regularly sit down for supper as a family?
2) Do my kids regularly get at least 10.5 hrs of sleep?
3) Do my kids have less than 2 hrs of screen time on weekdays?

A “no” to all of the above, probably puts your kids in the high-risk category, a “yes” to all of the above, and your kids are probably doing fine.

Now comes the tough part, i.e. wether or not, if you are not doing all of the above, simply doing these three things will actually change your kids risk for obesity. Or in other words, if you did nothing else, except sit down for dinner, have the kids in bed by 8.30, and limit their screen time, would your kids actually have healthy weights?

I am guessing that it will take far more than that. In fact I would not at all be surprised if the families that do any of the above were probably quite different from the families that don’t. I would indeed expect that these families are different in so many ways that really, these three factors are probably just “markers” rather than the actual explanation for the lower obesity risk.

Indeed, if you did have the time and parenting skills to ensure that your whole family sits down for supper, your kids don’t watch too much TV, and are off to bed at bedtime, then you are probably also doing a lot of other things right.

On the other hand, if your family meals are chaotic, you have no control over your kids’ screen time, and they are still running around at midnight, there are probably other issues that need to be addressed.

So while the findings are interesting (and by no means surprising), I am not exactly sure how they will help us address the childhood epidemic.

Perhaps a well-designed intervention study will show wether or not simply adopting these three “routines” will actually make a difference.

I certainly appreciate any comments or opinions on whether or not any of my readers think this will work.

AMS
Hamburg, Germany

Regular readers of these pages will recall several posts on the importance of adequate restorative sleep for the maintenance of healthy weights. As blogged previously, reduced sleep is not only associated with increased risk for obesity, but sleep deprivation also has profound effects on ingestive behaviour.

A new study by Schmid and colleagues from the University of Luebeck, Germany, published in the Journal of Clinical Endocrinology and Metabolism now shows that sleep deprivation can have profound effects on glucagon levels, a key determinant of glucose control.

Their study examined the effects of a single night of sleep restriction to 4.5 hours vs. a night of 7 hours of sleep in a crossover study in 10 healthy men.

Sleep deprivation not only reduced basal plasma glucagon levels but also glucagon response to a hypoglycemic clamp, but had no effect on circulating concentrations of insulin, C-peptide, epinephrine, norepinephrine, or growth hormone. Basal concentrations of ACTH and cortisol were also reduced after sleep loss during baseline.

This finding provides further evidence for the notion that glucose homeostasis is sensitive to subtle changes in sleep duration.

Importantly, as glucagon is a key hormone that helps maintain normal glucose levels during fasting by inducing the liver to convert stored glycogen into glucose and release it into the bloodstream, lack of glucagon release resulting from sleep deprivation could promote eating in response to hypoglycemia, thereby promoting weight gain. This may be of particular relevance to diabetic patients on hypoglycemic medications, who are particularly prone to hypoglycemic episodes.

This interesting observation clearly supports the notion that ensuring adequate amounts of sleep should be an important cornerstone of weight management.

AMS
Edmonton, Alberta

An interesting phenomenon of our times appears to be the number of people who consume the majority of their daily calories in the evenings or at night. I have previously blogged about the importance of eating regularly and not skipping meals, as this can promote homeostatic hyperphagia (overeating in response to hunger).

But new research suggest that there may be more to night-time eating than just an increased chance of overeating - it may well be that calories eaten at night are more likely to be stored as fat than the same amount of calories eaten during the day.

This notion is supported by a fascinating new study in mice by Deanna Arble and colleagues from Northwestern University, Evanston, IL, to be published in next month’s issue of OBESITY.

Based on a number of recent studies in animals linking energy regulation and the circadian clock at the molecular, physiological, and behavioral levels, Arble and colleagues examined the possibility that the timing of food intake itself may play a significant role in weight gain.

In their carefully conducted study, the researchers fed two groups of mice a high-fat diet with the same amount of calories for six weeks. The only difference between the groups was that one was fed at night (the normal eating time for mice, who are nocturnal), the other group was fed during the day (normally bedtime for mice).

Despite eating the same amount of calories and no change in activity, the mice fed during the day weighed 20% more at the end of six weeks and ended up with about 8% more body fat than the night-fed mice.

Thus, this study shows that simply changing the time of eating, without changing the number of calories can greatly affect body weight.

Although total calories and activity were not statistically different, there was a small trend towards more food intake and less activity in the day-fed mice, which may in the end have explained some of the difference, but by no means all of it.

Although the mechanism behind day-fed weight gain in mice is unknown, body temperature, satiety hormones and (lack of) sleep could contribute to this finding.

These findings, suggest that the synchrony between circadian and metabolic processes may play an important role in the regulation of energy balance and body weight control. As pointed out by the authors, “this study is the first to show causal evidence that feeding at the “wrong” time can lead to weight gain”.

If the same holds true in humans (and I can think of no reason why it shouldn’t), then eating when you should be asleep could be a key factor in promoting weight gain - something that all evening and night eaters may have to consider.

AMS
Edmonton, Alberta

Readers of these pages may recall an earlier post in which I proclaimed that the problem with fast food was more the “fast” than the “food” (no time to be thin? Jan 17, 2008). I have also regularly blogged on the emerging science on sleep (or rather lack thereof) and weight gain (Is Sleep Apnea a Significant Problem in Sleepy Kids? Jan 15, 2009).

Now, a new OECD report on social trends, including things like time spent on meals and time spent sleeping, shows that France, a country known for being one of the slimmest in Europe (10% obesity), spends the most time eating and sleeping compared to countries like Mexico or Canada with markedly higher obesity rates (around 20%).

According to the report, the French spend on average nearly 9 hours a day in bed and more than 2 hours a day eating and drinking — nearly twice as much time at the table as Americans, Canadians or Mexicans.

This of course does not imply that the French eat more - in fact, it is easier to overeat when you are gorging and gulping down your food than if you sit down to a slow 3 course meal (remember, the enteric-hypothalamic satiety axis operates on a 20-40 min time frame).

While there is only so much that can be derived from these type of comparisons, the findings are remarkably consistent with the emerging science of the importance of stress and sleep in relationship to obesity.

But there are certainly inconsistencies: Americans, with one of the highest rates of obesity, get almost as much sleep as the French; Koreans and Japanese, with less obesity, are at the lower end of the sleep scale.

So although obesity may well be a “symptom” of a society that does not take enough time to eat and sleep - the relationship is unlikely to be that straightforward.

Nevertheless, I’d certainly like to see an intervention trial that examines the effect of slow eating and more sleep on obesity prevention or management - may have to move to France to do it?

AMS
Edmonton, Alberta