Healthy Food & Healthy Living by Dr. Ayala

Why does losing sleep make you overeat?

We’ve all missed a good night’s sleep at one time or another, so we know first hand how important sleep is. Chronic lack of sleep is a bigger issue, it can make us moody and anxious, it reduces mental acuity, and it’s associated with increased likelihood of several diseases – such as viral infections, diabetes and heart disease.

Insufficient sleep is also associated with weight gain and overeating. 

A recent meta-analysis including 11 interventional studies – in which people with partial sleep deprivation were compared to controls who slept normally – found that shortened sleep is associated with eating an extra 385 calories.

Lack of sleep is now considered an established risk factor for childhood obesity, even though the data is mostly observational. An analysis of seven studies, including 14738 participants finds that from infancy into adolescence, sleeping less is linked with the development of obesity.

Sleep and weight gain are linked, but that doesn’t explain how one affects the other. What is it about sleeplessness that triggers weight gain? 

It may be that the lack of sleep activates hunger through a cascade of hormones. Lack of sleep may also just move people to eat in the absence of hunger – an emotional kind of eating that has more to do with comfort or mindlessness, not with real hunger urges.   

Not hungry, still eating

A new study in the American Journal of Clinical Nutrition including 105 kids aged 8-12 looks at what sleep deprivation does to eating in the absence of hunger, ie: eating for the sake of eating.

The kids, who all had normal sleep (8-11 hours a night), were assigned to 2 weeks of sleep restriction in which they went to bed one hour later, and the same kids were also tested with 2 weeks of sleep extension, in which they went to bed one hour earlier, the sleep settings done in random order. On the last day of each week the kids were given a buffet style meal, and told to eat until they were full. After a 15 minute break the kids were asked back into the dining room and given a free range of things like ice cream, chips, cookies and chocolate. Each kid’s consumption was measured in both the meal and the after meal by weighing what’s missing from the serving plates.

The authors found that the kids – who are basically compared to themselves – didn’t increase caloric intake when they lost an hour of sleep compared to when they gained one. What they did find is that after the first meal experiment the kids lowered their consumption during the first course, leaving more room for the dessert session for the remaining 3 weeks of their experiment. In other words, the kids learned that there’s sweet and salty stuff coming later, and adjusted accordingly.

When the researchers looked at all the kids together, after just the first week, before kids could learn that dessert was coming, they found that the mild sleep deprivation did increase the eating-while-not-hungry intake by a little, but the study sample wasn’t big enough to prove this point.

In this respect, this experimental model failed to prove that sleep deprivation leads to a greater tendency of eating while not hungry.

Eating while sleep deprived

This is, however, just the way science moves on. The observational data finds that sleep deprivation is clearly linked with overeating. Designing and implementing randomized controlled studies and manipulating sleep to further understand the mechanism and to establish causality is still needed, and obviously challenging. And we can never completely control for biases such as screen time and socioeconomic factors even though the statistical models take those into account. Questions remain.

But we can already say with some confidence that chronic sleeplessness is a common trigger for overeating.

It may simply be that being awake longer gives us more time to engage in our favorite activity.

And being tired may also make us more susceptible to the temptations of the kinds of foods that make us overeat: fast and energy dense ones – tired people aren’t likely to chop kale and dress it in lemon juice in the middle of the night.

Solving sleep isn’t easy, but being aware of the connection between sleep deprivation and overeating can make us a little more mindful of what we do when we don’t get enough sleep.

Dr. Ayala

Dream yourself thin?

Eat fewer calories and exercise more – that’s the age old recipe for weight-loss. But research suggests that we should add one more element to the regime: Get a good night’s sleep.

Studies have shown a link between obesity and lack of sleep, but the association by itself doesn’t give much of a clue as to which came first and doesn’t prove causality. Obesity can cause sleep problems (the most serious of which is obstructive sleep apnea). Being awake at night can increase appetite and night-time-snacking (kale isn't a popular midnight snack), and sleep deprivation can lead to poor food choices and inactivity.

A new review article in The Journal of Health Psychology examines how sleep impacts food intake, and shows that when sleep is disrupted our hormones (such as leptin and ghrelin) drive hunger, our cognition is impaired -- leading to less impulse control -- and we tend to look for pleasurable stimuli such as food to reward ourselves out of our crankiness. 

A study in the Annals of Internal Medicine isolated the effect of sleep quite nicely; it looked at overweight adults on a weight-loss diet, and showed that all other things being equal, lack of sleep hindered the dieter's ability to shed excess body fat.

That study recruited ten overweight healthy adults who were fed a moderate calorie-restricted diet. Dieters were randomly assigned to sleep either 5.5 hours or 8.5 hours each night, for two weeks on each regimen, in a closed clinical research environment. The researchers measured weight, but also measured body fat directly (using dual-energy x-ray absorptiometry or DXA), so they could calculate how much of the weight-loss was loss of fat, and how much of it was lean tissue or muscle loss. The results in this small group were quite clear Although overall weight loss was similar whether the dieters slept 5.5 hours or 8.5 hours, sleep restriction resulted in more loss of muscle and less loss of fat. More than half the weight lost during the 8.5 hours sleep condition was fat, compared to just one quarter in the 5.5 hour sleep condition. During the two weeks of sleep restriction, the dieters also felt hungrier

Sleep and muscle mass during weight-loss

When we ingest fewer calories than we expend – which is what happens on a weight-loss diet – the body goes looking for energy stores, and will break down both fat and protein to make sugars for energy.

The goal of any diet is to lose fat, not muscle. Not only do we like our muscle’s look and strength, muscles are active metabolically and burn energy, and loss of muscle during weight-loss diets is part of the reason people who've lost weight are so prone to regain it, and actually need to consume fewer calories just to keep their new weight stable. Preserving muscle is one of the reasons there’s such an emphasis on exercise during a weight-loss diet – working those muscles and building them is protection from dwindling muscle mass and slow metabolism. (For the sake of preserving muscle-bulk it’s also a good idea to avoid extremely low-calorie and nutritionally unbalanced weight-loss regimens.)

So a regime that protects muscle and leads to more fat-loss is very valuable. But don’t get excited just yet: This study involved only ten healthy participants, studied for a short while. But if results are confirmed by other studies this finding could be very important.

How could sleep affect fat loss? The researchers measured the levels of the hormone ghrelin and found that when dieters where on the sleep deprivation regimen ghrelin levels rose. Ghrelin, they reason, has been shown to signal hunger, reduce energy expenditure, hinder the breakdown of fat and increase the liver’s production of sugar. In this calorie deprived state of high ghrelin, the liver needs to make sugar while fat stores aren’t really open for providing building blocks, so it will break down muscle to fill the demand. There are, of course, many other possible ways in which lack of sleep may hamper fat-loss: fatigue may cause a dieter to be less active, and move less, for example.

More sleep less weight?

Sleep is one of the central pillars of good health. Sleep is absolutely critical to keeping us sane and happy. Yet we don’t give sleep as much respect as it deserves. 

Perhaps it's time to address sleep issues as part of any dietary intervention.

Dr. Ayala

Can adding sleep subtract pounds?

Many studies have shown that kids and adults who sleep less are more likely to be overweight or obese. This correlation doesn’t prove that sleeplessness causes obesity: Obesity can lead to sleep problems, and lack of sleep might be associated with socioeconomic factors, less organized homes and other factors that affect weight gain.

But a new experimental sleep study, reported in Pediatrics, actually looked at what adding and subtracting sleep did to weight and caloric intake in kids, and its findings suggest that just changing sleep duration may impact kids’ waistlines.

The less you sleep, the more you eat

The researchers asked 37 kids, aged 8-11 years, 27 percent of them overweight or obese, to sleep as usual for the first week of the study. During the second and third weeks the kids alternated between sleeping 1½ hour more and 1½ hour less per night for an entire week. Sleep duration was verified by an actigraph – a device that is placed on the wrist and monitors activity level. On average, the actual sleep difference between the week with increased and decreased sleep was about 2½ hours.

So what can 2½ hours do?  During the week the kids slept more they reported eating 134 fewer calories per day compared to their intake during the reduced sleep condition, and their measured weight was about half a pound less.

While you may frown upon the 134-calorie decrease, if such a reduction is maintained over a long period of time – something further studies that last longer than 3 weeks will need to prove – this would be enormous. Weight is usually gained slowly, by eating just a little more than necessary over long periods of time. The energy gap is the daily discrepancy between energy intake and energy expenditure, and for American kids, the average energy gap estimate is just 64 calories a day. Eliminating calories in just the double digits daily could prevent further weight gain and doing that in your sleep could be sweet!

The exact mechanism in which sleep affects weight is unclear. After a good night’s sleep we might be more active and burn more calories, we might have reduced appetites, and craving for high-calorie foods might be curbed.

Getting a good night’s sleep

Getting enough sleep helps kids grow, concentrate in school, feel good, and – as this study further confirms -- keep a healthy weight.

And while getting enough sleep isn’t always easy, one of the factors that affect sleep is in our hands. TV before bed has been shown time and time again to result in kids sleeping later, and having a screen in the bedroom not only reduces sleep – it is correlates independently with overweight. 

Dr. Ayala

Can You Sleep Yourself Thin?

I'll be taking a few weeks off to spend time with my family and travel, and will write infrequently during this time. Meantime, I'll be reposting some of the more popular posts I’ve written over the past years so that new readers have a chance to catch up.  Happy summer!

-----

“A good laugh and a long sleep are the best cures in the doctor's book.” ~Irish Proverb

Eat fewer calories and exercise more – that’s the age old recipe for weight-loss – the rest is gimmicks. But a new study suggests that we should perhaps add one more element to the regime: Get a good night’s sleep.

Sleep is one of the central pillars of good health. Sleep is absolutely critical to keeping us sane and happy. Yet we don’t give sleep as much respect as it deserves.

Several studies have shown a link between obesity and lack of sleep, but the association by itself doesn’t give much of a clue as to which came first and doesn’t prove causality. Obesity can cause sleep problems (the most serious of which is obstructive sleep apnea). Being awake at night can increase appetite and night-time-snacking (which usually isn’t green salad), and sleep deprivation can lead to poor food choices and inactivity.

But this new study in the Annals of Internal Medicine isolated the effect of sleep quite nicely; it looked at overweight adults on a weight-loss diet, and showed that all other things being equal, lack of sleep hindered the dieter's ability to shed excess body fat.

The study recruited ten overweight healthy adults who were fed a moderate calorie-restricted diet. Dieters were randomly assigned to sleep either 5.5 hours or 8.5 hours each night, for two weeks on each regimen, in a closed clinical research environment. The researchers measured weight, but also measured body fat directly (using dual-energy x-ray absorptiometry or DXA), so they could calculate how much of the weight-loss was loss of fat, and how much of it was lean tissue or muscle loss. The results in this small group were quite clear:

• Overall weight loss was similar whether the dieters slept 5.5 hours or 8.5 hours

• Sleep restriction resulted in more loss of muscle and less loss of fat: More than half the weight lost during the 8.5 hours sleep condition was fat, compared to just one quarter in the 5.5 hour sleep condition.

• During the two weeks of sleep restriction, dieters felt hungrier

Can a good night's sleep help preserve muscle during weight-loss?

When we ingest fewer calories than we expend – which is what happens on a weight-loss diet – the body goes looking for energy stores, and will break down both fat and protein to make sugars for energy.

The goal of any diet is to lose fat, not muscle. Not only do we like our muscle’s look and strength, muscles are active metabolically and burn energy, and loss of muscle during weight-loss diets is part of the reason people who've lost weight are so prone to regain it, and actually need to consume fewer calories just to keep their new weight stable. Preserving muscle is one of the reasons there’s such an emphasis on exercise during a weight-loss diet – working those muscles and building them is protection from dwindling muscle mass and slow metabolism. (For the sake of preserving muscle-bulk it’s also a good idea to avoid extremely low-calorie and nutritionally unbalanced weight-loss regimens.)

So a regime that protects muscle and leads to more fat-loss is very valuable. But don’t get excited just yet: This study involved only ten healthy participants, studied for a short while. But if results are confirmed by other studies this finding could be very important.

How could sleep affect fat loss? The researchers measured the levels of the hormone ghrelin and found that when dieters where on the sleep deprivation regimen ghrelin levels rose. Ghrelin, they reason, has been shown to signal hunger, reduce energy expenditure, hinder the breakdown of fat and increase the liver’s production of sugar. In this calorie deprived state of high ghrelin, the liver needs to make sugar while fat stores aren’t really open for providing building blocks, so it will break down muscle to fill the demand. There are, of course, many other possible ways in which lack of sleep may hamper fat-loss: fatigue may cause a dieter to be less active, and move less, for example.

Sleep isn’t a waste of time

Sleep is precious. Sleep isn’t always easy to get. Some people suffer from insomnia. Some work night shifts. Some have babies that make life look like a 
night shift. But for those of us for whom going to bed late is just a habit, I think it’s time to rethink sleep. I used to turn in after midnight – for no particular reason – it made me feel that there are bonus hours to my day. When I moved to the street I live on now I was surprised to see that most homes were dark by 10:30pm. I asked my neighbors what the lights-out was all about; they were astonished by the question. The thought of going to sleep at 10:30 never occurred to me, but I gave it a try, and was absolutely shocked by what a difference it made to my general well-being.

If you’re sleep deprived give sleep a try. Adequate sleep is underappreciated, and I believe it to be one of the most important ways to achieve optimal health. I’ll be curious to see if further studies confirm sleep’s role in fat-loss.

Dr. Ayala

 

 

Three healthy habits to help fight childhood obesity

I'll be taking some time off to spend time with my family and travel, and I'm be reposting a few popular posts I’ve written over the past years so that new readers have a chance to catch up. 

One in three American kids is overweight or obese. Many of our kids start accumulating extra weight—or develop the habits that will lead to weight gain later on—in very early childhood, setting them up for a lifelong struggle with both weight and a multitude of chronic diseases.

But many parents don’t pay much attention to obesity prevention advice; they don’t believe it’s relevant to their kids. They’re more focused on making sure their kids develop well, and they’re the last to notice when their kid puts on the pounds. And of course everybody hates “eat less” type of advice.

That’s why obesity-fighting tactics that aren’t directly related to what to put on kids’ plates have the potential of being successful.

A recent study in Pediatrics examined the association between childhood obesity and three household routines—regularly eating dinner as a family, getting enough sleep, and limiting TV-time—and found that 4-year-olds exposed all three routines had about a 40 percent lower prevalence of obesity than those exposed to none of these routines.

The study involved 8,550 nationally representative four-year-old American kids, and included measurements of height and weight as well as collection of background data, including ethnicity, maternal weight and education, and household income.

Eating dinner together regularly was defined as having the meal with at least some family members six or seven times a week. Adequate sleep for a four-year-old was categorized as 10.5 hours or more a night. Limited TV time was anything less than two hours a day during weekdays.

Here are the main findings:

• More than 18 percent (!) of the four-year-olds were obese.

• About half the families had a family dinner routinely.

• A little over a half of the four-year-olds got what the study considers enough sleep.

• 40 percent of four-year-olds had their TV time limited to less than two hours a day on weekdays.

• One in seven kids had all three household routines (family meals, enough sleep and limited TV time) and one in eight kids had none of these routines in place.

• Each of the routines was associated with significantly lower obesity rates. Kids who had all three routines had 40 percent less prevalence of obesity even after adjusting for maternal obesity and other socioeconomic characteristics.

Anything surprising in this data?

Unfortunately we’re getting used to seeing 18 percent obesity—yes, obesity, defined as a Body Mass Index (BMI) above the 95 percentile—not merely overweight in four-year-olds. That’s nearly one in five young kids!

Yet I still cringe whenever I see these numbers.

The finding that 60 percent of four-year-olds log more than two hours a day in front of the TV on weekdays is especially troubling to me. And I suspect these TV viewing times are an underestimate since parents tend to give socially desirable responses when asked about their habits, and only TV viewing athome and on weekdays was figured-in into this study.

Most large studies show that the more TV kids watch, the more likely they are to be overweight. How does TV contribute to obesity? Although common sense would say that TV displaces more active pursuits, that point isn’t well proven, as of yet.

What is very clear is that when our kids watch TV they are exposed to billions of dollars’ worth of well-crafted food ads, most of them for junk-foods: fast-food, sugary cereals and candy. These ads are so slick, and the marketing is so clever and entertaining that some toddlers have been known to sing the tunes and repeat the message after being exposed to some ads just once.

Most toddlers can’t tell programming and advertising apart—furry, cuddly friends and super-heroes abound in both—and it takes maturity and training to teach kids how to counteract the impact or to even notice the persuasive intent of advertising.

That’s why marketers want to get kids while they’re young; it’s like shooting fish in a barrel, and they’ll be loyal to the brand forever. That’s also why we parents should want to keep marketers away from our kids, especially when they’re very young and impressionable.

These days some food companies participate in a self-regulatory program butself-regulation doesn’t seem to be doing much to ensure responsible advertising to children. I actually don’t think there is such a thing as fair and responsible advertising to toddlers.

The American Academy of Pediatrics recommends limiting “children's total media time (with entertainment media) to no more than 1 to 2 hours of quality programming per day” and “discourage television viewing for children younger than 2 years”. TV is a babysitter every parent might want resort to every once in a while (we all need a break!) but common sense suggests that the upper limit should be lower than the Academy’s guide, and unfortunately, even quality programming is often flanked by ads. 

Should we adopt these three habits?

This study is cross-sectional and observational, meaning it looks at a population at a certain point in time and proves an association between family meals, good sleep and limited TV and lower rates of childhood obesity. It cannot prove causality, nor did the study examine the key influencers of obesity—diet and physical activity levels. It very well may be that these three habits are the habits of families who eat better and move more.

Yet even without further proof that these three habits curb obesity, I would absolutely recommend them to families, mainly because family meals, good sleep and limited TV-time make so much sense. There are other reasons to adopt these habits (for example, eating together is simply a good way to keep family ties strong), and there’s very little downside to embracing them.

But there are possible drawbacks. Your kids may suffer some arguments over the dinner table, have occasional bad dreams while they sleep, and miss some educational and entertaining stuff on TV.

On the other hand, they’ll be learning the pleasures and skills of dining in company rather than gulping down food, they’ll get enough sleep to sustain growth and health, and I’m pretty sure that most alternatives to TV (playing, reading or even being bored) offer better stimulation and sustenance to a child’s developing brain. If these three habits also protect young children from obesity, that’ll be a nice added bonus.

I’d take the risk.

Dr. Ayala

 

Kids aren’t getting enough sleep (and they never have)

Sleep’s a mysterious thing. We’re not sure what sleep is or why we need it, but we do know sleep is critical to our health and wellbeing. Lack of sleep has been associated with pretty much all that ails humans, and recently it has been also blamed for rising obesity rates.

Parents loose sleep worrying about sleep. Most parents believe their kids don’t get enough of it. We blame it on overscheduling, iPads, YouTube or our busy state of mind, but whatever it is, sleep’s always insufficient.

Sleep concerns are nothing new

A new study in the March issue of the journal Pediatrics finds concerns over kids’ sleep from the early 1900s were much similar to our concerns today. The researchers, led by Lisa Anne Matricciani, tracked more than a century’s worth of advice in more than 200 articles regarding children’s sleep, and compared it to data on how much kids actually slept over the years.

Kids always slept less that what health professionals thought they should -- about 37 minutes less than recommendations.

With the passing century sleep recommendations have also shrunk by a rate of about 0.71 minutes per year.

Our kids are indeed sleeping less: Sleep has declined about 0.73 minutes per year in the past century. That amounts to our kids slumbering about 20 minutes less than we did, and 40 minutes less than their grandparents. 

“Modern Living” robs kids’ dreams

Our great grandparents shared our perception of life going faster and faster, and a British Medical Journal editorial from 1894, titled “Sleeplessness”, cited in the article, states “The hurry and excitement of modern life is quite correctly held to be responsible for much of the insomnia of which we hear.” 

The novel preoccupation of the day has always been charged with keeping kids away from shuteye: first it was books, then the radio, and later TV, the Internet and social media.

How much sleep do kids need?

Despite finding 35 sets of recommendations about optimal sleep duration, the study discovers that the sleep need of kids remains a big unknown. Recommendations were based largely on opinions, which were based on, well, nothing really.  We have no scientific clue how much sleep kids need.

But in case you’re curious about current recommendations take a look here; these, too, I assume are based on observations and very little evidence. If your kid is tired and cranky, he’s not getting enough sleep. 

The kids are all right 

There was something comforting about reading this research. It suggests we’re just a link in a generational chain of worrying parents.

When my kids ask why I worry about them so much I say it’s moms' nature to worry -- I guess it served our species well to be cautious and protective of our young. 

We may long for bygone, simpler times, but the kids never slept enough, whatever that enough might be, and nevertheless, they’re probably going to turn out just fine. 

Dr. Ayala