Dr. Sue's Seminars

How N.E.A.T. Are You - And Could It Be Affecting Your Weight?

2012-01-08T09:05:00.002-07:00

While the factors contributing to obesity and weight change are extremely complex, it is a truth that an increase in body weight is the result of a higher caloric intake compared to caloric expenditure (ie calories in is more than calories out). One major risk factor for obesity appears to be our individual tendency to engage in NEAT ('non exercise activity thermogenesis'), and by making changes to one's NEATness, one may find themselves a giant NEAT leap ahead in the struggle against the bulge.

Calories Out (ie, caloric expenditure) is made up by the following constituents:

Basal Metabolic Rate: This is your baseline metabolism at rest, and comprises about 60% of total daily calorie burn in a relatively sendentary person. It is determined primarily by your body size and body composition - in particular, your fat free (lean) body mass (as muscle, which is lean, is more metabolically active than fat).
Thermic Effect of Food: This refers to the calories burned by the process of digestion of food, and is responsible for about 10% of your total day's calorie burn. This varies a little depending on what you eat, as protein takes about 25% more energy to digest than carbs or fat.
Activity Thermogenesis: These are the calories you burn by moving around.

Activity Thermogenesis is further broken down into:

Exercise thermogenesis (from purposeful exercise: playing hockey, going to the gym, etc); and
Non Exercise Activity Thermogenesis (N.E.A.T. - there it is!). NEAT refers to any calories burned by moving around during the day that is not related to focused exercise: this can be walking to work, moving around at the office, doing chores at home, painting a fence, playing a piano, etc.

As most people around the world do not specifically exercise, and because those that do exercise typically engage no more than a couple of hours per week, NEAT is far and away the greatest component of the total number of calories that we burn by moving around.

If we look at the explosion in obesity around the world in the last century or so, we can see that there has been a parallel decrease in our daily NEAT activities. We have become a society that can shop online, drive to work, and purchase a self powered vacuum to clean up the crumbs around the couch from last night's TV marathon. We have also become a society that is much more efficient in the workplace, with machines that do much of our manual labor for us, technology that allows transfer of information in an instant rather than by hand, and workplaces moved to the home as there is often no longer a reason to physically relocate oneself to an office on a daily basis. Unfortunately, this caloric 'efficiency' has taken a toll on our health as a society, making it all too easy to pack on extra pounds from the larger portion sizes and unhealthy choices that plague our marketplace.

Add to this another level of complexity: genetics. As suggested by JA Levine, an authority on the topic of NEAT from the Endocrine Research Unit at the Mayo Clinic, it may be some of us are genetically endowed to be NEAT activators (who would have gone out to hunt in the face of famine in the 'olden days'), while others are NEAT conservers (who would tend to lay low, conserve energy, and weather out the famine until food became more plentiful again).   In modern day, a NEAT activator may be a person who is more likely to fidget, or may choose the stairs instead of the escalator; a NEAT conserver may be genetically more inclined to sit at their desk rather than stand, or may choose to drive to work rather than ride a bike in the interests of time (though the transportation issue is clearly much more complex and often environmentally determined - read more here).

So, how can we increase our NEATness? As proposed by Dr Levine, try the STRIPE approach:

S:   SELECT a NEAT-activity that you enjoy and start it (walking to work, standing while talking on the phone, going dancing rather than to a movie);

T:   TARGET specific goals for your NEAT activity and follow through on them

R:   REWARD yourself for reaching your identified goal (eg treat yourself to a new song on iTunes to listen to after your first month of walking to work)

I:    IDENTIFY barriers & remove them (eg go to the mall to walk and talk with a friend if it gets too cold to walk outside);

P:   PLAN NEAT-activity sessions,

E: EVALUATE yourself: have you stuck to your plan, and has it been effective in reaching your goals?

When you choose your NEAT activities, be sure that they are activities that you enjoy! Make moving fun. :D

Thanks to my friend and Danish research colleague Mads Rosenkilde for the inspiration to write this blog, and for the heads' up on a great review article by Dr Levine.

Dr Sue

www.drsue.ca © 2012 drsuetalks@gmail.com

Follow me on Twitter for daily tips! @drsuepedersen

Physical Activity Alone Doesn't Prevent Weight Gain for Most Women

2011-08-26T16:38:00.000-06:00

I am often asked by my patients if it is possible to prevent weight gain by maintaining high activity levels, without giving special consideration towards food intake. An important study from the Journal of the American Medical Association tells us that physical activity is not enough to prevent weight gain for most women.

The study by I-M Lee and colleagues surveyed over 34,000 American women over a 16 year period, and asked them to report their weight and physical activity levels. They were classified into one of three levels of activity:

less than 150 minutes of moderate intensity exercise per week
150-420 minutes of moderate intensity exercise per week
420 or more minutes of moderate intensity exercise per week (at least 1 hour per day)

The study found that for women who were overweight, there was no difference in weight gain over time between each activity group. It did not seem to matter how much exercise overweight women engaged in; weight gain was the same regardless.

Interestingly, they found that physical activity was helpful to prevent weight gain in some women who were not overweight (ie, with a Body Mass Index of ≤ 25; you can calculate your own BMI here, in the right hand column). It is no cake walk, though (so to speak) - in order for normal weight women to prevent weight gain with exercise, they had to engage in at least one hour of exercise per day.

The take home messages, as I see them, are:

1. For most women, exercise alone is not enough to prevent weight gain. Weight management is more about watching what you eat, rather than how much you exercise.

2. Regardless of whether or not exercise will prevent further weight gain, it is still very important to exercise for its other health benefits! Exercising for 150 minutes per week has been clearly shown to lower the risk of chronic diseases, so it remains of crucial importance to continue to exercise for the benefit of your overall health. (Before engaging in, or stepping up, an exercise program, be sure to speak with your doctor to make sure you are making changes safely.)

3. For normal weight women, at least an hour a day of moderate activity is necessary for exercise alone to prevent weight gain over the long haul.

You can read about the Canadian Physical Activity guidelines here to find out how much exercise is recommended. Check out Health Canada's website for further details, and some great ideas as to how you can work exercise into your daily life!

Dr. Sue © 2011 www.drsue.ca drsuetalks@gmail.com

The Trials and Tribulations of Urban Transport

2011-07-09T12:58:00.000-06:00

In last week's post, I blogged about the sad state of some rural Canadian roads - the shoulders being too narrow and covered in rumble strips, with no option for a cyclist to safely enjoy a day on the road. This week, allow me to rant about the problems that plague urban North America, making it difficult, and sometimes impossible, to get around on our own steam!

For the first time since I started working at my current clinic location (and that's a year and a half!), I decided to brave the roads and cycle to work one day last week. I live 5km from my office, so it would seem on the surface that it would actually be very convenient to cycle there. Well, let me tell you... I am not sure how many lives I'm going to get, but I think I used up about a dozen of them during that 10 km round-trip adventure. Although Calgary is known as a city with one of the best cycling path systems in Canada, this system is only useful for daily transport if you are so lucky to both live and work somewhere along its length. Most of us are not so geographically lucky to have both work and home on the system, so we're exposed to the elements of regular traffic if we want to ride.

Obstacles/health hazards encountered on my adventure to and from work included:

no cycling lanes
drivers who did not show any interest in yielding to, or even minding, the cyclist;
sidewalks did not have graded curbs on the corners (making these areas highly inaccessible to people in wheelchairs, never mind bikes)
many through roads were blocked off by industrial companies with fences around their properties, necessitating back tracking and finding curcuitous routes
random hubcaps, broken glass
the same train track had to be crossed three times before reaching my destination

So for me, some big changes would have to be made before I would consider riding my bike to work again. Our new mayor has made it a priority to improve cycling access and safety, so let's see what happens. Contrast this with the year I spent working at the University of Copenhagen, where the society is so geared towards bike travel that it actually dissuades one from wanting a car. Coincidentally, I lived the exact same distance from work in Denmark that I do here in Calgary (5km), and when I calculated the calorie burn over a year of cycling to work - it equated to 18 pounds of body fat! This focus on self powered transport is one contributor to the lower obesity rates seen in Denmark (11%, compared to 25% in Canada, and 34% in USA).

This week's biggest hats off goes to the people of the Netherlands, who are turning to cycle powered school buses to help their children stay active and safe (pictured above)! I love it. It appears that the company that makes these buses, De Caferacer, also makes these buses for adults (if there are any Dutch speakers out there who can help me out with the website, please feel free to comment on this post - my Danish is not saving me here!).

For those of us back in North America - we'd sure love to incorporate these self powered buses as transport, but the reality is that our entire society will require an infrastructural overhaul before that would even be possible. Fair enough to say that our climate is not as permissive of this form of travel, but for half the year, it would still be a blessing!

Thanks to my friend Brian at marketinghits.ca for the heads' up on the great photo!

Dr Sue

www.drsue.ca © 2011 drsuetalks@gmail.com

Follow me on Twitter for daily tips! @drsuepedersen

Ready to RUMBLE??

2011-07-02T08:07:00.002-06:00

North America suffers some of the highest rates of overweight in the world, with 66% of American adults and 59% of Canadian adults affected. Although the list of contributing factors is long and complex, there is no doubt that an infrastructure and attitude that promotes sedentary living is clearly a major issue.

I took the above photo at last year's meeting of the American Diabetes Association in Orlando, FL, USA. This is one of the largest gatherings of health care providers interested in the treatment and prevention of diabetes on earth, and yet, when offered the option, the escalator was usually preferred to the stairs. Part of the problem here was the construction of the conference centre: while an escalator is certainly important for accessibility for people unable to take the stairs, are two sets side by side really necessary?

For people who try to engage in more healthy leisure activity, golf has really taken off as a popular activity. Golf can provide fantastic exercise; within the space of an afternoon, several kilometres can be walked and enjoyed with friends or colleagues. Sadly, many golf courses now don't allow patrons to walk the course, insisting that they use a buggy so that more players can be moved through! While golf courses were previously built to walk, many are now developed with the goal of maximizing real estate property on the course, which results in an enormous golf course which may not even be practical to walk.

The tipping point which stimulated me to write this blog on this particular week was a recent experience I had on the rural highways in Southern Alberta. I was out for a fantastic ride on my road bike on a fairly quiet highway, with beautiful views and great weather to accompany me on my journey. The shoulder was narrow, but I felt comfortable.... until I came upon a long stretch of rumble strips that had been planted in the middle of it! Unfortunately, there was no cycle path alongside for cyclists to move to; the choices were to brave the traffic, or turn around. This is in stark contrast to many other countries around the world, where there is a priority on accessible and safe self-powered transport, which not only helps to keep people active, but also saves on CO2 emissions and keeps road traffic more manageable. I certainly understand the need to alert drivers with rumble strips if they get distracted and are edging towards the side of the road, but this should not be at the sacrifice of others who are trying to enjoy the road under their own steam.

As North Americans, it is upon each of us to work exceptionally hard to find ways to stay active in our environment. Maybe it's time to rumble with policy makers to make our infrastructure more conducive to physical activity.

Dr Sue Pedersen www.drsue.ca © 2011 drsuetalks@gmail.com

Are We Getting Our 10,000 Steps Per Day?

2011-05-14T07:41:00.001-06:00

As part of living a healthy lifestyle, it's important to make a point of being active on a daily basis. Though this used to come naturally to our ancestors, we have to make a purposeful point of moving these days, as our society is built to promote a sedentary lifestyle where we can get most of our daily tasks accomplished without moving much at all. Thus, one piece of counseling that health care providers often give (including myself!) is to take 10,000 steps a day. To confirm that I am practicing what I preach, I donned a pedometer a couple of weeks ago to check out my own daily steps.

I must admit to you that prior to this little self-experiment, I was confident that I was well over my requisite 10,000 steps. I rush around all day long in a whirlwind of activity as many of you do as well - there was no doubt in my mind that I was making the cuts!

Well....was I wrong!

In a crazy day in my clinic, running literally up and down the halls all day, it turns out that I bag only 2,000 steps. This was a disappointing realization! The first day I discovered this, I thought, no matter, I still have errands to run at the grocery store... those laps up and down the aisles will be sure to get me there. Nope - just 600 steps more. (I even took a couple of extra trips down the veggie aisle to buff this up a bit.) A walk to the gym and back (from the parking lot) gets me another 1,200 steps... and then there's about another 500-1000 steps around the house between the start and end of the day.

My grand total for a typical, very busy day, ranges between 3,000-4,500 steps. Not even half!

This is why we all need to have a purposeful focus on activity on a daily basis. Other than those lucky few of us who truly engage in physical exercise at the workplace (manual labor, or a self-propelled transport/delivery job such as newspaper delivery), we simply do not get enough exercise in our day.

There are two ways to solve this dilemma:
1. Focused physical activity (workouts at the gym, running, cycling, skiing, etc)
or
2. Modification of daily life to accomplish those 10,000 steps!

The science behind the 10,000 steps is that walking this distance (about 8km or 5 miles) is equivalent to about a 500 calorie burn (though this amount will vary depending on how much you weigh). If you have a 500 calorie deficit per day, this would result in one pound of weight loss per week - but remember that this has to be 500 calories above and beyond what you take in. Also remember that if your weight is stable, you'd have to walk an additional 10,000 steps above and beyond what you already do, without eating anything extra, in order to lose weight at that rate. Sound difficult? - It is!! This is why the studies show overall that exercise alone does not result in weight loss - unless it is accompanied by a calorie reduced diet. However, exercise remains crucially important as it has many health benefits, and is very important for weight maintenance as well.

Modification of daily life to increase your daily steps can include any number of things:

park at the far end of the parking lot (it is interesting to observe people circling the lot at the gym to get the spot closest to the door!)
walk into the the store instead of using the drive-thru
go to the mall instead of shopping online
take the dog for a longer walk
get off the bus one or two stops earlier
and the list goes on!

Wearing a pedometer is a great way to monitor and motivate yourself - studies show that it is those of us who walk the least, who benefit the most from this wonderful little tool.

For me, I'll keep up my workouts at the gym to make sure I top my 10,000 steps worth of activity each day....and I'll take our dog for a few more trips around the block!

I'd love to hear about your experiences with your pedometer, and how you've modified your life to increase your steps!

Dr. Sue © 2011 www.drsue.ca drsuetalks@gmail.com

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Canadian Physical Activity Guidelines - Are You Getting Enough?

2011-02-05T13:06:00.000-07:00

In today's society, most of us do not exert ourselves physically unless we make a conscious effort to set aside special time dedicated towards physical activity. As such, it is important that we are all making sure that we do get enough exercise, and Canada now has brand new guidelines. Are you getting enough?

On January 24th, the Canadian Society for Exercise Physiology published the 2011 Canadian Physical Activity Guidelines, which are easily downloadable for free online. There are four sets of guidelines for different age groups, each on an easy-to-read one page summary sheet. Here is a summary of what is currently recommended:

Children aged 5-17 years:

at least 60 minutes of moderate to vigorous intensity physical activity per day:
this should include vigorous activity at least 3 days per week;
this should include activity that strengthens muscle and bone at least 3 days per week

Adults:

at least 150 minutes of moderate to vigorous intensity aerobic physical activity per week, in bouts of 10 minutes or more
add muscle strengthening activities using major muscle groups, at least twice a week
for adults aged 65 and older, those with poor mobility should perform physical activities to enhance balance and prevent falls

It is noted for all age groups that more daily physical activity (above what is recommended) provides greater health benefits. Specific helpful suggestions are also provided for the different age groups for possible activities to engage in.

Take a moment and review these guidelines with your family - are you and your loved ones getting enough exercise? If not, think about how you can work some extra activity into your daily life. Remember that before you engage in any new exercise program, it is important to speak with your doctor to review the safety of any planned changes in physical activity in the context of your personal health; in some cases, a heart checkup (possibly with additional testing) is important before engaging in any new exercise. No different that getting your bike checked after some time in storage, before you take it for a ride!

Have fun!!

Dr Sue Pedersen www.drsue.ca © 2011 drsuetalks@gmail.com

Follow me on Twitter for daily tips! @drsuepedersen

Inspiration to Exercise!

2010-09-12T21:18:00.002-06:00

Although it seems that summer has all too rapidly come to a close in western Canada, race season is still in full swing. I competed in the bike leg of a team triathlon in Banff on Saturday (a personal first), and I spent Sunday as the physician on call for the Dinosaur Valley Half Marathon in Drumheller, AB (www.dinosaurhalf.com). During the weekend, I had the opportunity to observe and be inspired by the athletes, and to think about the variety of ways in which people motivate themselves to exercise and stay active.

One key theme was that people were often found to be competing in groups. At the marathon, I met mothers and daughters, friends, and neighbors who had banded together to train up for race day. Although triathlons are traditionally a solo sport, there were many groups who enrolled as a three person team, with one person assigned to each of the swimming, cycling, and running legs of the race. For myself, it was a great opportunity to enrol as a family and cheer each other on at our respective sports. For all of these groups, the important message that shone through each time was that having the common goal of the race in mind provided an excellent opportunity to support each other through the months of training before the race. It's true - exercise programs are often more successful in a group support setting than when a person tries to go it alone. Consider planning workouts with a group of at least 3 people, such that if one person cancels, the other two can still provide mutual motivation to burn some calories!

Another theme was the sense of accomplishment that arose from participation in these events. At the Dinosaur Valley marathon, I had the great joy of watching contestants of all ages and abilities walk or run anywhere from 5km to a full half marathon (26km). I was equally inspired by every individual who competed, because I knew that each person was challenging themselves personally to accomplish their goal. Aspiring towards a personal best provided sufficient motivation for many an athlete to train towards their goal in the preceding months. I came across a number of athletes this weekend who were going it solo, and felt that the drive to succeed was motivation enough!

One interesting theme I heard time and time again, was that people who were racing were doing it to set a good example for their children. Childhood overweight has become a serious problem, and although there are many contributory factors, a key contributor is the increase in sendentary behavior that has been noted (TV watching, internet, etc). At the Banff Triathlon, there was many a child cheering on their parents as they crossed the finish line. At the marathon, I was thrilled to see whole families running the 5km race together!

These are just a few ideas to consider to increase motivation and adherence to exercise. To all this weekend's competitors - hats off to you!

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Normal Weight Obesity Part II

2010-06-05T08:54:00.000-06:00

Thanks to all of my readers who provided feedback, comments, and questions regarding last week's blog on Normal Weight Obesity. The questions generated were important, and I'd like to share some of these key issues with you this week!

One of my readers enquired as to whether everyone in the normal BMI range (18.5-25) is at risk of Normal Weight Obesity (NWO). The answer is that the higher your BMI is within the normal range, the higher the risk of NWO. In other words, an individual with a BMI of 19 is extremely unlikely to have NWO, whereas an individual with a BMI of 24 has a higher likelihood of NWO. (Stay tuned for a little more detail on this one - I've just submitted a research article for publication along with my colleague Dr. Arne Astrup in Copenhagen, looking at our own DEXA scan data and BMI misclassification rates.) Women are also at higher risk of NWO than men.

Another important issue to point out is that the opposite classification problem can occur as well: that is, that some people are classified as being overweight by BMI, but do not have excess body fat. Men are at higher risk of this type of misclassification than women (though it can happen in women as well). Picture, for example, a male hockey player with lots of lean muscle mass, and a BMI of 27. This individual is overweight by BMI criteria, but his fat mass may be only15%, well under the 25% fat mass cutoff that defines excess body fat in men. It would be entirely inappropriate to recommend to this hockey player to lose weight!

This example highlights the importance of having other estimates of body fat than just BMI. Waist circumference can be helpful as well: you could imagine that the ultra-fit hockey player would have a trim waist, whereas a sedentary man with a BMI of 27 may be collecting a little extra around his midline. Our ideal upper limits for waist circumference are:

Caucasian, Middle Eastern, Africans: men 94cm, women 80 cm
South Asians, First Nations, Chinese, and Japanese: men 90 cm, women 80 cm

This discussion also highlights another important issue with regards to weight struggles, and that is to remember to take pride in a change in body composition that you might be making by stepping up your exercise routine, even if you are not seeing a change in weight. Building muscle in place of fat is beneficial in terms of decreasing your risk of complications of excess body fat (cardiovascular disease, high blood pressure, and many others), and will likely also provide you with an improved sense of general well being and overall health. Changing your body composition in favor of less body fat is a victory in itself!

Dr. Sue © 2010 www.drsue.ca drsuetalks@gmail.com

Canadians have become More Overweight and Less Fit!

2010-03-21T18:08:00.002-06:00

It comes as no surprise that Canadians have become more obese and less sendentary over the last 25 years. However, statistics from the Canadian Health Measures Survey have now put some numbers on the scope of the problem, and the results aren't pretty.

In the 1970's and 80's in Canada, there was a period of time where fitness was taken more seriously, at least in part due to the governmental ParticipACTION campaign. In 1981, the Canadian Fitness Survey reported that 56% of Canadian adults were active in their leisure time.
In 2008, that number has dropped to only 33%. Even worse - only 13% of Canadian children meet guidlines for recommended amounts of physical activity. Muscular strength and flexibility have fallen in Canadian adults, and the proportion of young adults with a waistline that puts them at risk of cardiovascular and metabolic health problems has more than quadrupled.

The need for more action from the government is clear. Comparisons to Canadian anti-smoking campaigns are often made; while the stop smoking campaigns have been comprehensive and strong, the committment by our government to promote active living has waxed and waned over the past decades. ParticipACTION lots its federal funding in the early 2000s, but was resurrected in 2007.

An easy way that we can all engage in active living is simply to incorporate activity into our daily ttransport routines. Taking the stairs instead of the elevator to get to your office or apartment is an easy one (if this is difficult at the start, try taking just one flight of stairs, and hop on the elevator for the remainder; you can build it up over time!). Park your car blocks away from your office and walk the rest (you may even save on parking this way!).

I learned a lot from the year I spent working at the University of Copenhagen, Denmark last year, with regards to active transportation. In Copenhagen, there are more bikes than there are cars, and rush hour bike traffic is a way of life. I rode my bike to work every day, which was only 5km away - but by the end of the year, this amounted to 2,000 km of cycling! Clearly, the Canadian climate is not always conducive to cycling to work, but even doing this for 8 months of the year would be an important contribution to an active lifestyle. Interestingly, even back in 1973 when Canadian dedication to an active lifestyle was stronger, the fitness of our 30 year olds was comparable to the fitness of a 60 year old Swede, which is at least partly attributable to this active transport lifestyle.

Dr. Sue © 2010 www.drsue.ca drsuetalks@gmail.com

Ten Reasons to Exercise!

2009-07-31T01:29:00.000-06:00

I am often asked if it is necessary to exercise to shed pounds. The short answer to this is no - you can certainly lose weight by decreasing your caloric intake alone, and in fact, dietary changes are probably more important than alterations in your activity level. However, it is clear that we live in a sedentary, internet-driven society, and the more time we spend sitting still, the lower our caloric expenditures will be! Our bodies were built to use - so - let's get out there and use them!

Remember that it is important to:

a) increase your exercise gradually, to avoid injury and to be sure you can tolerate it; and

b) discuss your exercise program with your doctor before you start, to get the A-OK to go ahead with your plan! (your doctor may want to do some tests of your heart and/or exercise tolerance before you start)

Here are ten great reasons to exercise! (and I have a hundred more...)

1. Being active will increase the difference between Calories In (what you eat) and Calories Out (activity) - the bigger the difference, the faster you will shed pounds! It is clear that exercise results in weight loss as well as a reduction in body fat.

2. Exercise increases your sensitivity to insulin, putting less stress on your pancreas to control your blood sugars.

3. How cool is this: Adhering to a physical activity program results in a decrease of 6,000 heart beats per day in men, and 3,000 heart beats per day in women! (and yes, this is after taking into account the increased number of heart beats during the workout itself). Think of all the work you are saving your heart in the long run!

4. Regular physical activity improves your sensitivity to other hormones as well, such as adrenaline and glucagon, both of which are involved with regulation of your blood sugar levels. Thus, exercise overall enhances the accuracy of your body to regulate use and storage of sugar and fat.

5. Several studies suggest that exercise provides some protection against cancer, specifically breast cancer, pancreatic cancer, and other intestinal malignancies.

6. Reduce your stress! There's nothing like a good workout to burn off some stress after a hard day at work.

7. Amongst older individuals, exercise decreases the risk of dementia and Alzheimer's disease (one study showed a 40% decreased risk of Alzheimer's!).

8. Cure those blues! Exercise decreases the risk of depression and anxiety as well.

9. Working out regularly decreases your risk of developing type 2 diabetes.

10. Because it's FUN!! Find an activity or sport that you enjoy, and make the most of it!!

Dr. Sue © 2009 www.drsue.ca drsuetalks@gmail.com

The Fat Burning Zone: Truth or Hype?

2009-07-18T03:21:00.002-06:00

I am often asked about what intensity of exercise is the most effective for weight loss. At the gym or on your home workout machine, you may have noted that the medium range of exertion is labelled as the 'fat burning zone', and the intense range of exercise is labelled as the 'carb burning zone'. Based on this, many people conclude that they will lose weight (fat) faster if they exercise at moderate intensity, than if they work out at a higher intensity.

True or False?

The short answer: False!

The long answer:

Your rate of weight loss, or weight gain, is based simply on the difference between your Calories In (what you eat) and your Calories Out (what you expend). So, if you exercise at a higher intensity for a fixed period of time (let's say, cycling hard for 30 minutes), you will burn more calories than if you do the same activity for the same period of time, but at a moderate intensity (cycling at a medium intensity for 30 minutes).

So what is this 'fat burning zone' all about? Well, it is true that when you exercise at moderate intensity, your metabolism is in a zone where it will choose primarily fat as its fuel source, whereas when you are in the high intensity zone, your body is choosing carbohydrate as its primary energy source. The key point, however, is that the body is exceptionally talented at moving energy stores around between fat, carbohydrate and protein. Thus, when all is said and done, the body will balance out these energy stores again, such that it is prepared for the next period where you demand of it again. So while you burn proportionally more fat (relative to carbohydrate) at medium intensity, the overall calories burnt is lower, and once your body finishes redistributing your energy stores, you end up with more energy (including fat) left in your body than if you had exercised at a high intensity. At the high intensity, on the other hand, your body would have burned proportionally more carbs (relative to fat), but after re-equilibrating, your body would have had to draw on some fat stores to replenish the carb stores, and with less calories overall in your body, you will also have less fat! (It is a bit more complicated than that, but this is the jist of it.)

Repeated over time, the difference between moderate and high intensity workouts adds up! If you burn an extra 100 calories per day (which can be very reasonably accomplished by turning up a moderate 30 minute workout into an intense one), you will lose 10 pounds in a year. This, of course, assumes that you have recognized and avoided the #1 PITFALL of high intensity workouts to the person trying to lose weight - and that is that high intensity workouts can make you HUNGRY!! An appetite just as intense as the workout you just had can result in overconsumption of calories, to the point where you have lost the benefit of the intense workout, and perhaps eaten yourself into bringing more Calories In than what you put out! One third of a Snickers bar can wipe out that 100 calorie extra burn that you got from your workout.

If you decide to step up your workouts, make sure you speak with your doctor first, particularly if you have any medical conditions. It is also advisable to ramp up your workouts gradually rather than just jumping into hard core workouts - this is safest from a cardiovascular perspective, and also helps to avoid injury.

Dr. Sue © 2009 www.drsue.ca drsuetalks@gmail.com