Arya M. Sharma, MD

Today’s post is another excerpt from “Best Weight: A Practical Guide to Office-Based Weight Management“, recently published by the Canadian Obesity Network.

This guide is meant for health professionals dealing with obese clients and is NOT a self-management tool or weight-loss program. However, I assume that even general readers may find some of this material of interest.

EXERCISE AND ACTIVITY

Exercise is an important determinant of health, and has beneficial effects on aerobic fitness, insulin sensitivity, blood pressure and coronary heart disease risk reduction, regardless of a patient’s weight. It is also an important factor in weight management.

Asking patients about the type and amount of physical activity they undertake on a daily basis provides clues about the amount of energy they expend. It is important to explore types of activity undertaken at work and during leisure time. Patients may describe themselves as extremely busy and active at work, but careful questioning may reveal that they are in fact running to and from the car, to and from the elevator, and to and from their desk. While busy, they are not really physically active at levels sufficient to elicit an exercise response.

Different occupations involve different levels of activity, but in our day and age, it is exceedingly rare for a patient to be very physically active at work. Even occupations that were traditionally quite strenuous, such as farming, have incorporated labour- and time-saving devices that increase productivity while diminishing the farmer’s expenditure of physical energy.

One way to obtain an objective measurement of activity is using a pedometer. Patients may talk of targeting 10,000 steps in their weight-management program, but a target set too far above what the patient is accustomed to is much less likely to be met. Establish a baseline and work from there to gradually increase activity levels.

Patients will often complain they do not have time for physical activity. It is important to explain that, from a weight-management perspective, exercise is cumulative and they do not need to find an hour every day to devote exclusively to physical fitness. Every 10 minutes of exercise counts, and virtually everything counts as exercise: walking, gardening, house work, playing with children, etc. Only a small minority of patients can motivate themselves to visit a gym on a regular basis, but most can find multiple 10-minute blocks of increased activity a day.

If patients have exercise equipment in their homes, encourage them to move the treadmill or stationary bicycle from the basement to the living room where it can better assert its existence.

Patients can be taught to establish cues that will help them remember to exercise. For example, to watch a favourite television program, they must be at least walking on the treadmill. Reward systems work too: for every ‘x’ minutes of exercise, the patient allows him- or herself some form of non-food-based reward.

Explain to patients that the calories they burn through exercise on a daily basis are not significant enough to warrant extra foods or increased portion sizes. People dramatically overestimate the calories burned through exercise, so remind them that the calories burned in 30 minutes of intense exercise can be consumed in 30 seconds with an increased portion size or a simple chocolate bar. However, over time, exercise can have a dramatic impact on weight and can greatly reduce the risk of regaining lost weight.

© Copyright 2010 by Dr. Arya M. Sharma and Dr. Yoni Freedhoff. All rights reserved.

The opinions in this book are those of the authors and do not represent those of the Canadian Obesity Network.

Members of the Canadian Obesity Network can download Best Weight for free.

Best Weight is also available at Amazon and Barnes & Nobles (part of the proceeds from all sales go to support the Canadian Obesity Network)

If you have already read Best Weight, please take a few minutes to leave a review on the Amazon or Barnes & Nobles website.

Preeclampsia, a potentially life-threatening complication of pregnancy, is more common in women with excess weight and there is now considerable evidence that the risk for this problem can be reduced with exercise.

Interestingly, a previous randomised-controlled intervention in 124 pregnant women reported that simple stretching exercises, consisting of slow muscle movements that had neither aerobic nor muscle resistance components, performed 5 times a week starting at 18 weeks of gestation, very impressively reduced the risk of early signs of preeclampsia, compared to walking 40 mins 5 times a week (2.6% versus 14.6%).

Now, a paper just published in the American Journal of Perinatology by Sowndramalingam Sankaralingam and colleagues from the University of Alberta, suggests that this difference may be due to a more positive effect of stretching exercises on reducing oxidative stress in blood vessels of these participants.

Immunohistochemical analyses of blood vessels embedded in fat biopsy samples obtained during cesarean sections from some of the women who were randomized to either stretching ( N = 6) or walking ( N = 5) exercises in this larger study, showed remarkably higher expression of the antioxidant superoxide dismutase (SOD) and plasma transferrin levels, an antioxidant marker.

In addition, plasma levels of transferrin continued to increase throughout gestation only among the stretchers.

Thus the authors conclude that the beneficial effect of regular stretching exercises during pregnancy not only trump the benefits of walking may be attributable to the higher antioxidant protective effect of this low-intensity exercise during pregnancy.

Incidentally, in the original study, walkers tended to exercised less than stretchers both overall and as pregnancy advanced, suggesting that stretching may be a better intervention as it is easier to perform and adhere to during pregnancy.

While neither stretching nor walking had any effect on body weight, it is certainly worth considering that stretching exercises should perhaps be routinely prescribed and encouraged in women at risk for preecmlampsia.

AMS
Edmonton, Alberta

Sankaralingam S, Jiang Y, Davidge ST, & Yeo S (2011). Effect of Exercise on Vascular Superoxide Dismutase Expression in High-Risk Pregnancy. American journal of perinatology PMID: 21815126

Readers will recall my recent post on the notion that the weight-loss that occurs in some people with exercise is probably related more to the impact that exercise has on caloric intake than on the actual amount of calories burnt.

It is therefore not all that surprising, that a systematic review and meta-analysis of the literature on the impact of isolated aerobic exercise on body weight, by Adrian Thorogood and colleagues from Montreal and Quebec, published in the latest issue of the American Journal of Medicine, shows rather limited impact of this intervention on body weight.

In their study, the researchers, searched for all published randomized controlled trial reports of aerobic exercise through January 20, 2010 and identified 14 trials involving 1847 overweight and/or obese patients.

While six-month programs were associated with about 1.6 Kg reduction in weight and about 2 cms reduction in waist circumference, twelve-month programs did not lead to any additional weight loss.

As the authors note:

“Previous systematic reviews suggest a linear dose-response relationship between aerobic exercise and weight loss, but only for interventions <16 weeks in duration with a controlled diet. This relationship has not been shown for longer interventions.“

These findings have some important clinical implications.

1) When indicated(!), taking up an aerobic exercise program alone (i.e. without also changing your diet), is not the most effective way to achieve even a modest 5% weight loss.

2) The study also shows that maximum weight loss with this intervention is probably achieved after about six months, whereafter, continued exercise helps maintain weight loss, but does not reduce weight further.

Of course, none of this should be taken as an excuse to abandon or not include a healthy bout of aerobic activity into your daily routine. However, if your only goal is to lose weight (which, by the way, it should not be), you are likely to be disappointed.

Indeed, there is ample data showing that including regular exercise into your routine increases your chances of maintaining weight stability and avoiding weight regain.

And of course, there are countless benefits of exercise, that cannot be measured on a scale.

In the end, weight loss requires reducing and restricting caloric intake - the idea that you can ‘burn’ enough calories through exercise to lose and significant amounts of weight is nonsense - alas, a myth that sells gym memberships and keeps hosts of weight-loss TV shows in business.

Finally, let’s always remember that neither diet nor exercise alone should ever be seen as a treatment for obesity, at least not without first conducting a careful evaluation of the potential causes and consequences of excess weight and carefully weighing the pros and cons of any weight-loss recommendations.

AMS
Cambridge, UK

Thorogood A, Mottillo S, Shimony A, Filion KB, Joseph L, Genest J, Pilote L, Poirier P, Schiffrin EL, & Eisenberg MJ (2011). Isolated aerobic exercise and weight loss: a systematic review and meta-analysis of randomized controlled trials. The American journal of medicine, 124 (8), 747-55 PMID: 21787904

Regular readers will recall my recent posts on the notion that the benefits of regular exercise on body weight are largely mediated by the positive impact on caloric intake rather than by the number of calories burnt.

This notion is based on the idea that exercise modulates eating behaviour by reducing stress, improving mood, and perhaps, even by reducing the ‘reward’ response of palatable foods.

The latter assumption, is supported by a recent stud by Maciej Buchowski and colleagues from Vanderbilt University, Nashville, Tennessee, published in PLoS.

The study was conducted in 12 sedentary or minimally active non-treatment seeking cannabis-dependent adults, who attended 10 supervised 30-min treadmill exercise sessions standardized using heart rate (HR) monitoring (60-70% HR reserve) over 2 weeks.

Self-reported drug use reduced from about 6 joints per day to less than 3 joints a day during the exercise intervention and remained at 4 joints per day 2 weeks after the end of the study.

Average Marijuana Craving Questionnaire factor scores for the pre- and post-exercise craving assessments were also markedly reduced for compulsivity, emotionality, expectancy, and purposefulness.

As the authors discuss:

“Consistent with the changes in cannabis use reported by participants, subjective cravings elicited by cannabis cues were also significantly reduced by exercise, suggesting the possibility that the potential therapeutic effect of exercise may be mediated via brain mechanisms responsible for cue-induced craving.

These same brain mechanisms have been invoked in behavioral addictions involving non-drug rewards, as is observed in overeating and obesity, problematic hypersexuality, and pathological gambling. Analogously, it has been reported that exercise activates some of the same reward pathways as are activated by addictive drugs. For instance, acute bouts of exercise increase central dopamine concentrations and chronic exercise leads to sustained increases in dopamine concentrations and compensatory alterations in dopamine binding proteins in brain regions relevant to reward.”

Thus, the findings from this rather small study provides the basis for conducting a much larger and longer-term study on the use of exercise as a treatment for marijuana addiction.

On the other hand, given important role of the brain’s reward circuitry for food in take, it may not be expected if such a study also demonstrates a positive effect on overconsumption of highly palatable foods.

AMS
Dushesnay, Quebec

Buchowski MS, Meade NN, Charboneau E, Park S, Dietrich MS, Cowan RL, & Martin PR (2011). Aerobic exercise training reduces cannabis craving and use in non-treatment seeking cannabis-dependent adults. PloS one, 6 (3) PMID: 21408154

Regular readers may recall that I posed this question in a post earlier this year.

In it, I proposed that the positive impact of regular exercise on body weight has more to do with the positive effect of exercise on dietary caloric intake than on the number of calories ‘burnt’ - in other words, exercise is more about ‘calories in’ than ‘calories out’.

Following the rather enthusiastic response to this post, Jean-Philippe Chaput (a former CON Boot Camper and now an Assistant Professor at the Childrens’ Hospital of Eastern Ontario in Ottawa) and I co-authored an editorial on this topic for the British Journal of Nutrition.

The original post can be read here.

AMS
Edmonton, Alberta