The Role of Exercise in Weight Loss: Part 3
Part 3 of 3.
Over the past couple of articles, we’ve explored the role of exercise in weight loss and discovered:
#1: Exercise alone isn’t very effective at producing weight loss.
#2: Resistance training during a diet is a must for protecting muscle mass and metabolism.
Of course, these two observations run counter to the time-honoured tradition of prescribing loads of aerobic training as the primary tool for weight loss. This begs the question: where exactly does aerobic training fit into the weight loss picture?
Undeniably, aerobic training does burn calories. In fact, I’ve had someone argue that a calorie burned through exercise is superior than a calorie omitted through the diet. Interesting theory; let’s find out if this might be true.
A recent study addressed this very question1. Over a 6-month period, researcher followed 48 overweight participants who were divided into 4 groups.
- Control: keep on with business as usual.
- Caloric restriction: They got 25% fewer calories than what would be required to maintain their current weight.
- Caloric restriction + exercise: They got 12.5% fewer calories, plus expended an additional 12.5% of calories through aerobic exercise.
- Low calorie diet: They got 890 kcal/day until they lost a total of 15% of their body weight, and then were put on a weight maintenance diet.
As part of the exercise program, participants were asked to complete five aerobic training sessions per week. Females were required to burn 400 kcal per session whereas males were required to burn 570 kcal per session. The average length of time spent exercising was 45-50 minutes, so overall it was well within the norms of what a recreational exerciser might actually do.
As an aside, I’d just like to point out that equating the caloric deficit between the 25% diet and 12.5% diet + 12.5% exercise is a great touch. Many studies trying to compare exercise and diet fail to balance the caloric deficit in both conditions, then go on to make erroneous claims about the effectiveness of one intervention over another.
Back to the data… at the end of the 6-month period, the researchers found that:
- Controls didn’t lose much of anything (big surprise)
- Dieting was as effective as caloric restriction + exercise
- The drastic low-calorie diet causes the greatest weight loss, but also resulted in the greatest loss of fat-free mass loss as well (not a good thing)
So the Coles Notes version suggests that a massive caloric restriction (down to only ~900 calories a day) produces a massive weight loss, with a corresponding massive loss in muscle mass. I think we can all agree that is not the way to go for long term success.
What is most shocking, is that total weight and lean mass losses were identical between the diet and the diet + exercise group. Wow, not only did aerobic exercise fail to produce any kind of metabolic advantage, it also failed to adequately protect muscle mass. Things are not looking good for our dear friend aerobic training…
However, even though aerobic training didn’t help with additional weight loss or protect muscle mass, the research team did find one significant benefit, a protection of metabolism.
One of the unfortunate by-products of dieting is that it leads to a down-regulation of metabolism (in part due to a loss of muscle) as well as a decrease in spontaneous physical activity.
If you move less, you burn less.
Consider it part of your body’s mechanism to force you to regain whatever weight you just lost. As stated in an earlier article, humans aren’t designed for weight loss!
In the graph below, we can see that the only group that maintained or improved their total daily energy expenditure was the group that performed the frequent exercise.
Even though this didn’t translate to differences in weight loss, it still could result in significant weight control benefits in the long run. It is reasonable to expect that the group that moves more, could lose more in the longer run.
At the risk of sounding like a broken record, I must once again highlight that the fastest way to lose weight is through your diet.
Unless your idea of a good time is spending 4-5 hours a day training, motivated by your harpy-voiced, Jillian Michaels-esque trainer; you must clean up your diet if you want to lose weight.
However, I much as I love to stress the importance of clean eating, we should also discuss the mechanics of long-term weight control.
Truth be told, losing weight and maintaining weight loss are two very different physiological states, although most researchers either neglect or don’t understand this point.
The processes that allow you to successfully lose fat are different than those that allow you to keep fat off and those are different from those that lead to fat gain in the first place. No wonder there is so much conflicting data and confusion out there!
To date, all the studies I’ve presented on aerobic training and fat loss applied to the benefits (or lack thereof) of cardio during a diet.
Based on what we’ve seen, cutting calories below a maintenance level is easier to accomplish through diet and adding aerobic training doesn’t seem to create any significant additional benefit. Mind you, I would argue that creating a caloric deficit massively below maintenance levels isn’t your best way to lose weight, but that’s a topic for a whole other series of articles!
The big problem with dieting is that while it works great to produce fat loss, in the real world, most people can’t or won’t significantly reduce caloric intake for very long periods of time.
Feeling hungry, tired and cold just aren’t physiological states that most people look forward to with gusto.
So although dieting is great as a short-term intervention, you can’t use aggressive caloric restriction as a long-term solution for body weight regulation.
After a few months of dedicated dieting and the proper lean mass preserving approach to exercise (i.e. resistance training), people need to transition into a maintenance phase. And once we switch our goal from losing weight to maintaining weight loss, suddenly aerobic training takes on a whole new level of significance!
A brilliant study2 was published a short while ago looked into this. The study involved 4 groups of overweight adult females on a calorie restricted diet (1200-1500 kcal/day). The groups differed on the amount and intensity of exercise they were asked to perform.
- Moderate volume (1000 kcal/week), moderate intensity (50-65% of max HR)
- High volume (2000 kcal/week), moderate intensity (50-65% of max HR)
- Moderate volume (1000 kcal/week), high intensity (70-85% of max HR)
- High volume (2000 kcal/week), high intensity (70-85% of max HR)
The beauty of this study was that it covered a 2-year period and looked at 6 months of weight loss, followed by 18 months of maintenance.
Two years is an eon in research years, so we can actually start to ascertain legitimate effectiveness of various interventions.
Although a long study period means participants lose interest and adherence to the protocol can wane, I would argue the results are a more accurate reflection of reality.
And what did they find after two years?
Everyone lost a good amount of weight over the first 6 months on a diet (between 9-12% of your starting weight). Chalk another one up for the effectiveness of diet + exercise in being able to produce weight loss for all. But as the months drag into years, some striking differences emerge on the ability to sustain that weight loss.
At the 2-year time point, the only group that completely maintained their weight loss is the group devoting more than 300 minutes to exercise! Doing some quick math tells me:
300 minutes = 5 hours = 2000+ kcal expended per week
This level of activity is needed in addition to a clean diet.
In contrast, the individuals completing 150 minutes of exercise a week (5 sessions of 30 minutes), lost a bunch of weight early, but regained a good portion of it back over the following 18 months.
Clearly, the myth that 30 minutes of exercise a few times a week is all you need to lose weight is just a convenient way to sell exercise videos and programs that might result in some initial weight loss, but will keep you from achieving your goals in the long run.
Which brings us to:
Reality check #3
To lose weight and keep it off, dedicate 5 hours each week to exercise.
Obviously there are exceptions to this rule. If you do a lot of supa-maximal training, you likely will need less volume. Similarly, if you have great genetics, you could need less exercise. But let me tell you now, you probably don’t qualify as an exception 😉
Mind you, this study only assessed the impact of aerobic training and found that ~5 hours to be the magic number. Clearly you can also burn calories performing resistance training, playing squash, doing yoga or walking a 6 km golf course with a 20 lbs bag on your back.
All physical activity contributes to better weight management. Moreover, the best results are found in those individuals who spend time working on muscle mass, flexibility, cardiovascular function as well as allow themselves psychological release in “play” activities.
But for now don’t obsess about the perfect program, instead start working towards getting your 5-hours of activity each week.
As much as I love to critique the plethora of incompetent personal trainers out there, it’s actually not their fault you aren’t losing weight. If might be their fault you are too weak to snap a piece of chalk or have the work capacity of a 2-year old, but unless you are religiously seeing them 5x/week, then you are going to need to take a majority ownership of your weight loss efforts.
This means finding another 2-3 hours for exercise outside of any training sessions or boot camps you may be attending. Although this might seem staggering, countless other societies accumulate five hours of activity per day, so spending 5 out of the 168 hours in a week being physically active should be no big deal.
If you are totally lost with the best way to start, it pays to have someone design a comprehensive workout plan for you that incorporates both resistance training and energy systems work (a fancy and more accurate term that encompasses different forms of “cardio” training).
Heck, you’ll probably also want to invest in a customized meal plan and/or nutrition coaching to get your diet sorted out. Although everyone loves to claim they eat healthy, the fact most of us are carrying a lot of excess body fat suggests otherwise.
But regardless of your diet and exercise preferences, if you currently struggle to control body weight, incorporating 5 hours/week of structured physical activity and controlling your caloric intake need to be your primary goals.
Hey, maybe that’s not the reality you wanted to hear, but that’s life.
This statement isn’t intended to discourage you from taking action or making it seem that long-term weight control is next to impossible.
Rather, it is designed to remind you that guidance is good, but at the end of the day you are still responsible for implementing the necessary diet and exercise changes that allow for both weight loss and long-term weight management.
Once you realize that you have the power to control how you look and feel, achieving your goals becomes a simple matter of taking action.
Till next time, train hard and eat clean!
1. Redman LM et al. (2009). Metabolic and behavioral compensations in response to caloric restriction: Implications for the maintenance of weight loss. PLS one, 4, e4377.
2. Jakicic JM et al. (2008). Effects of Exercise on 24-Month Weight Loss Maintenance in Overweight Women. Archives of Internal Medicine, 168(14): 1550-1559.