Dr. Sharma's Obesity Notes

Despite all advances in gender equality, mothers overwhelmingly remain responsible for putting food on the family table.

Thus, any attempt at changing eating behaviours requires a sound understanding of the factors that determine mothers’ food choices for their families.

This issue is the topic of a study by Joyce Slater and colleagues from the University of Manitoba, published in Health Promotion International.

The researchers used qualitative methodology based on grounded theory to better understand the phenomena of food choice and food provisioning among employed middle-income mothers from Winnipeg.

All participants were born in Canada, were Caucasian, worked at least half-time at paid employment, lived with a male spouse working full-time, had at least one child between ages 5 and 12, had some post-secondary education and self-identified as having the primary responsibility for acquiring and preparing food for her family.

The methods consisted of extensive interviews and use of food choice maps to explore a wide range of determinants of food practices and choices.

Perhaps not surprisingly, the number one constraint that limited the preparation of healthy home cooked meals was lack of time!

As one participant put it:

“Life is far too rushed! Especially if you’re only getting home [from work] at, like anything after five is just a disaster. If you’re not home before quarter to five it’s like, you’re not going to make it! ‘Cause there’s evening events that are going to start and it’s like, oh man, now it’s the rush and a panic.”

The two main reasons for lack of time were employment and kids activities.

“All the women in this study described their family lives as being extremely busy due to their employment and children being engaged in multiple extracurricular events, which were felt to be important for their development. This contracted their food preparation time, however, resulting in the frequent use of convenience foods or take-away from restaurants, which also led to feelings of stress.”

The second major determinant of food choices were ‘picky eaters’:

“My daughter’s very picky, so who knows what she’ll eat what nights … it’s usually just a Pizza Pop or leftovers of a quick bowl of soup. We try to get her to eat what we eat, but it’s challenging. You don’t want it to be a battleground.”

While breakfast and lunch were rarely eaten together, most mothers appreciated the importance of having the family assembled for dinner - however, this also rarely happened due to busy and conflicting schedules.

Although mothers collectively perceived food as an important determinant of health,

“Many of the foods children preferred were perceived to be unhealthy by the mothers, but were frequently purchased because they knew they would be eaten, or it was believed that the children should have their way at least some of the time.”

Reasons for not eating enough fruits and vegetables boiled down to:

“…children not liking vegetables; they took too much time and work to prepare; it was not worth making them only for themselves and the women did not want to risk spending time making vegetables if they were going to be wasted.”

Although mothers appreciated that fathers may have a role to play - they preferred to make these choices themselves:

“Sometimes I wish he would help a bit more, but I still think I’m better off with the majority of it. Because, I said, I don’t think he would make as good of choices. He would give the kids Pizza Pops for lunch every day, and … vegetables?! Who cares? What do you need vegetables for!?”

“[Help with] groceries? No (laughter), not very often! I mean, you know, if I’m really really strapped he will go out but that’s not that often. He really doesn’t like grocery shopping.”

All of these findings have significant implications for improving population health:

“By purchasing and serving convenience foods over vegetables and healthier meals that take more preparation time, the women reinforce structural food norms within the family and within the retail grocery landscape that provides these foods for purchase. “

“Shifting norms surrounding the efforts put into food preparation are mutually reinforced by the women’s values, beliefs and identities, permitting the frequent use of these foods, thereby saving time. This is compounded by working outside the home and a busy family life, which leave considerably less time for preparing healthy foods and eating together. “

As the authors point out, educating mothers (or fathers) about healthy eating, although important, is insufficient to really change behaviour.

“Public health policy-makers should expand nutrition education initiatives to include … a more balanced discussion of domestic food work rather than perpetuating the current discourse on child obesity calling for greater ‘parental’ (maternal) responsibility. This could also include providing more flexibility for employees (male and female) to work part-time.

In addition, strategies to promote the uptake of more family food responsibility by male partners and children should be explored and promoted. A step towards this could be achieved through a re-introduction of school-based nutrition and food skills, not through traditional ‘home ec’ curriculum with gender-specific stereotypes, but teaching basic principles to feed young men and women, and their future families, within the current food environment.”

As I’ve discussed before, when trying to understand behaviours, it is far more important to explore the ‘why’ than the ‘what’.

This study certainly reminds us that for many, the key barrier to healthy eating is not lack of information on nutrients and food groups but rather having far too few minutes in your day.

Remember, the real problem with fast food is more the ‘fast’ than the ‘food’

AMS
Edmonton, Alberta

Slater J, Sevenhuysen G, Edginton B, & O’neil J (2011). ‘Trying to make it all come together’: structuration and employed mothers’ experience of family food provisioning in Canada. Health promotion international PMID: 21693474

If going on a diet or starting an exercise program resulted in persistent weight loss,  we would not have an obesity epidemic.

Unfortunately, as anyone who has tried this knows, maintaining a significant degree of weight loss requires daily dedication, motivation and a limitless supply of will power - nothing short of developing a compulsive obsession.

As readers will recall, the biology of the post-weight loss state is nothing like the biology of someone who has never lost weight. There are countless ways in which the psychoneurobiology, energy physiology and metabolism in anyone who has lost weight are remarkably different from someone ‘naturally’ of that weight.

Simply stated, someone who was 150 lbs and has lost 20 lbs cannot hope to maintain that weight loss by simply eating the same amount of food or doing the same amount of exercise as someone who is ‘naturally’ a 130 lbs.

The 150 lbs person who has lost 20 lbs, to maintain their new 130 lbs, has to actually now live like someone who is ‘naturally’ a 110 lbs; just eating like someone who is 130 lbs but has never lost weight, will simply result in rapid weight regain.

This is why just cutting out a few ‘extra’ calories or walking a few ‘extra’ steps is not an effective or sustainable strategy for maintaining weight loss - for any clinically meaningful weight loss (when indicated) - we are looking at cutting hundreds of calories from the diet and adding hours of serious exercise per week - forever!

A comprehensive and fascinating overview of the fundamental changes that occur with weight loss to ultimately make sustaining this new weight an ongoing challenge, is discussed by Paul Maclean and colleagues from the University of Denver Colorado, in a paper just published in the American Journal of Physiology.

The authors provide a detailed synthesis of data from a wide range of weight loss studies that include studies in clinically overweight and obese adults, in diet-induced, polygenic animal models of obesity, and with dietary (non-surgical) interventions involving an energy restricted low fat diet.

The consistent finding from all such studies is that all individuals or animals in a post-weight-loss state face considerable ‘homeostatic pressure’ that aims to drive their weight back to initial levels.

The paper extensively discusses how changes in biological signals of fat stores (e.g. leptin) elicit profound metabolic and behavioural adaptations - a topic that I dealt with extensively in previous posts.

The key findings of increased hunger and appetite, reduced satiety and substantially increased ‘fuel efficiency’ have very real underlying biological drivers - drivers powerful enough to ultimately wear down even the most persistent dieter.

As the authors point out - persistent dieting is so difficult because it requires maintaining a remarkably large ‘energy gap’:

“Because both sides of the energy balance equation are affected after weight loss, the biological pressure to gain weight is a consequence of both increased appetite and suppressed energy expenditure.

During weight maintenance after weight loss, this energy gap reflects the magnitude of the daily burden that thwarts cognitive efforts to maintain the reduced weight.

Regardless of which side of the energy balance equation is most affected, the energy gap imparts a substantial pressure to eat in excess of the energy requirements.

The magnitude of the energy gap is greatest at the nadir weight after weight loss. Likewise, this energy gap does not dissipate with time in weight maintenance. Rather, studies in DIO (diet induced obesity) models indicate that the magnitude of the energy gap gradually increases the longer they maintain their reduced weight with an energy restricted diet .

The implications from these observations are that the biological pressures may strengthen with time and the amount of lost weight, gradually increasing their perceived influence.”

The paper also extensively discusses some of the lesser known metabolic adaptations to weight loss including profound changes in gut biology that enhance caloric extraction from food as well as alterations in liver function, skeletal muscle and fat tissue that promote weight regain.

While all of this may seem hopeless to readers, the authors actually end on the rather positive note that:

“… only by acknowledging that these homeostatic pressures emerge, we can proactively develop and implement regain prevention strategies to counter their influence. To ensure success, the regain prevention strategies will likely need to be just as comprehensive, persistent, and redundant, as the biological adaptations they are attempting to counter.”

Obviously, it is also important to note, that no ‘weight-loss strategy” actually addresses the many complex reasons why people may gain weight in the first place.

Whoever said that treating obesity was simply a matter of ‘eating less and moving more’ (ELMM) probably also believes that they can live forever by simply breathing less.

AMS
Burlington, Ontario

Maclean PS, Bergouignan A, Cornier MA, & Jackman MR (2011). Biology’s Response to Dieting: the Impetus for Weight Regain. American journal of physiology. Regulatory, integrative and comparative physiology PMID: 21677272

Longtime readers may recall a post explaining why hunger makes you eat crap.

Understanding this, is an important principle to promote healthy eating and weight management (not necessarily the same).

To make this message somewhat easier to communicate, I produced this brief video, which hopefully brings this very simple but important point across (subscribers may have to visit my site to view this video).

Very much appreciate your comments and please feel free to repost.

AMS
Leipzig, Germany

Readers will recall a post earlier this week on the importance of sleep for weight management.

Researchers and clinicians, wanting to know more about the underlying biology and mechanisms on how lack of sleep, disruption of circadian rhythm (e.g. through shift work, jet lag, or having a baby), and alterations in light/dark cycles can impact ingestive behaviour and energy metabolism may wish to read a comprehensive review just published in the Annals of Medicine.

In this paper, Russel Reiter and colleagues from the University of Texas, San Antonio, summarize the potential contributions of three processes that may be contributing to humans becoming progressively more overweight: circadian or chronodisruption, sleep deficiency, and melatonin suppression.

As the authors point out:

“Circadian disruption, sleep deficiency, and melatonin suppression have at least one common causative feature, i.e. excessive light exposure including even brief periods of light at night. Indeed, interrupting the normal dark period with a short interval of bright light may be the most disruptive. Certainly, light pollution throughout the world, and especially in the economically well developed and developing nations, where obesity is also the most common, has become a major problem and is a serious concern. The use of artificial light after darkness onset in the evening and in the morning before sunrise is commonplace and impacts the physiology of the circadian system which influences both nocturnal melatonin synthesis and sleep. Moreover, being exposed to light after darkness onset due to what is referred to as trespass light or intentionally turning on a lamp is disruptive to the circadian system, which reduces melatonin levels and disturbs sleep.“

Obviously, looking at bright light sources such as a TV, a computer screen or a backlit e-Book can be even more disruptive.

Perhaps we should now all plan for candle-light dinners and then call it an early night?

AMS
Leipzig, Germany

Reiter RJ, Tan DX, Korkmaz A, & Ma S (2011). Obesity and metabolic syndrome: Association with chronodisruption, sleep deprivation, and melatonin suppression. Annals of medicine PMID: 21668294

The idea of using electrical stimulation to affect gastric motility and emptying as a means to increase satiety and reduce appetite has received a considerable amount of attention.

Regular Readers may recall that, although two gastric stimulators have now been approved for obesity treatment in Europe, US studies on gastric stimulators for the treatment of obesity, have unfortunately not lived up to expectations.

A study published in OBESITY suggests that perhaps rather than electrical stimulation of the stomach, stimulation of the large intestine (colon) may provide a more promising approach.

This idea is based on the finding that key hormones and neuronal signals that affect gastric motility and satiety (e.g. PYY-36) are in fact released by the colon.

In this pilot study, Hanaa Sallam and Jiande Chen from the University of Texas, Galveston, examined the effect of colonic electrical stimulation (CES) using implanted electrodes in dogs and found (compared to sham-stimulation) that CES delayed gastric emptying of solids by 77%, reduced intestinal contractility, and resulted in a 60% reduction in food intake.

The fact that this response was partially inhibited by guanethidine (an autonomic ganglion blocker) suggests a role for the autonomic nervous system in mediating this effect. In fact, CES decreased vagal activity in both fasting and fed states, increased the sympathovagal balance and marginally increased sympathetic activity in the fasting state.

While these findings do suggest that the colon may prove a novel target for efforts to use electrical stimulation to treat obesity (remember, electronic pacemakers are now routinely used on a number of other organs in medical practice), it will certainly take a lot more research before this may indeed be considered an actual treatment option for obesity.

In particular, one would like to certainly better understand exactly how colonic electrical stimulation produces this profound effect on appetite and food intake and that this acute effect continues to be active with prolonged stimulation.

Nevertheless, the results do point to the fact that the colon can potentially play an important role as a target organ in the treatment of obesity.

AMS
Edmonton, Alberta

Sallam HS, & Chen JD (2011). Colon Electrical Stimulation: Potential Use for Treatment of Obesity. Obesity (Silver Spring, Md.) PMID: 21660079