In Training the Obese Beginner: Part 1 I took little bit of a complex/technical look at some of the physiological “defects” that are often seen when obesity develops. Continuing with that I want to look at a few more physiological issues including muscle mass, metabolic rate (mainly to bust a common myth) and the realities of exercise in the beginner/obese beginner population.
Increased Muscle Mass
Perhaps surprisingly, one of the consequences of developing obesity is that some proportion of the total weight gained is lean body mass (LBM). Quite in fact, this may make up an average of 25% of the total weight gained. So if someone gained 100 pounds, as much of that could be 25 pounds of LBM. I’d note that the process is not unlimited. At some point, obese individuals come up a maximum limit on LBM (similar to the one seen in natural lifters). From that point on, weight gain is 100% body fat.
Perhaps more surprisingly, given that there is no training involved, at least some of this LBM is actual muscle mass. You’ve probably noticed the large thigh and calf size among heavier individuals. In a very real way, the process of becoming obese is a type of progressive overload for the lower body. As bodyweight goes up, muscle mass has to increase as well.
Of course, not all of it is muscle tissue and there are also increases in glycogen, water, minerals and connective tissue. This all counts as LBM and some researchers refer to this as “inessential LBM” to differentiate it from “essential LBM” (muscle and organs).
Given that 25% of the weight gain that occurs when obesity develops is LBM, at least some researchers feel that up to 25% of the total weight lost can safely come from LBM. At least so long as it’s coming from the inessential LBM that was gained. Yes, this does go against the general belief that any LBM loss on a diet is negative but this is a different situation.
In lean individuals, the loss of LBM is a very real problem since essentially any LBM that is lost will be primarily from muscle mass. In the obese individual, the lost LBM not only represents what was gained but much of it is “inessential” to begin with. Quite in fact, to achieve a “normal” body weight (whatever that means) may require losing some of that “extra” LBM. Ideally it would be mostly “inessential” LBM but even losing some of the “extra” muscle that was gained may be beneficial in some cases.
Why Is This Important?
So why am I bringing this up other than to show off my incredible knowledge of useless physiological minutiae? Here’s why: In training the obese beginner, individuals with a proximity bias for the weight room often put a lot of their energy into having the individual lift weights. They figure that’s what should be done in the gym, and that’s what they like to do, so that’s what all their clients do. And it tends to be a real waste of time and energy beyond a certain point.
Usually, there are two goals of increasing muscle in the obese beginner.
The first is an attempt to increase metabolic rate and energy expenditure. This stems from the long-held misconception that muscle burns a lot of calories or that gaining muscle is a good way to boost energy expenditure. And it’s not. One pound of muscle only burns about 6 calories at rest and the impact of this is absolutely miniscule. Even if someone gained 10 pound of muscle the increase in energy expenditure is only 60 calories. It would take months and ultimately have no real impact on anything.
It also takes a lot of training time, training time better spent focusing on active fat loss and increasing energy expenditure, usually through cardio exercise. In this vein, I’d refer readers back to the Biggest Loser feedback I got where the contestant stated that they did 75% aerobic activity and 25% weights. As much as I dislike how the Biggest Loser approaches this thing
The second comes from the idea that increasing muscle mass will automatically lower body fat percentage.
This segues into the misguided notion that increasing muscle mass will automatically lower body fat percentage. As I’ve discussed previously, the impact here is minimal. Even fairly large scale gains in muscle mass do very little to lower body fat percentage. In contrast, losing fat has a much much larger impact.
Gaining 5 pounds of muscle will have a negligible impact on BF% and might take two or more months for a male beginner (and twice as long in women). Losing that same 5 pounds of fat will have a significant impact on BF% (and health) and will take a fraction of the time to accomplish. Hell, under extreme conditions, a very obese dieter can lose 5 pounds of fat in a single week. Gaining that same amount of muscle takes months.
Cardio vs. Weights
Related to this is that you can almost always burn more calories during cardiovascular/aerobic exercise than in the weight room. Though, as I’ll discuss below, it’s not as if the typical beginner burns a lot of calories during either. And no, the whole afterburn/EPOC thing is not a consideration. The impact is miniscule approaching irrelevant, especially for the types of activity that beginners can generally tolerate. The calories burned during the exercise will always be the major contributor.
None of which is meant to say that weight training isn’t important or useful for other reasons in this population. Rather, what I’m saying is spending an inordinate amount of time on weight training with the obese beginner is a misdirected effort. It’s time spent that is unlikely to massively impact on the overall goal or outcome but which takes training time from the things that will.
Should some weight training be done by the obese beginner? Absolutely. Should a lot be done? No.
I’d note that even in the Biggest Loser Feedback piece I ran, the writer mentioned that their training was about 25% weights/75% cardio. As much as I dislike what the show does for the most part, this at least makes sense. I could even see a more skewed ratio but the Biggest Loser is mostly about doing what looks good on TV, not what is the right kind of training. And watching people do cardio isn’t very exciting so they have to dick around with weight training stuff to get an hour’s worth of television out of it.
While this doesn’t have a hugely practical impact on anything, I want to talk a little bit about metabolic rate in obese individuals. Primarily to address the long-held (and wrong) belief that the obese suffer from a low metabolic rate and that this is part of the predisposition to weight gain.
Now the number of calories burned in a day, called Total Daily Energy Expenditure (TDEE) has four different components.
- Resting Metabolic Rate (RMR): The number of calories burned at rest
- Thermic Effect of Food (TEF): The number of calories burned in digesting and metabolizing food
- Thermic Effect of Activity (TEA): The number of calories burned in formal exercise
- Non-Exercise Activity Thermogenesis (NEAT): Calories burned during any activity that is not formal exercise
In this section, I am focusing almost exclusively on RMR, the number of calories burned by the body at rest. As I said, there is a long-held belief that obese individuals have a low or decreased RMR and you will still hear people say “I have a slow metabolism.”
And, at least when looking at RMR, it’s completely false. The simple fact is that studies routinely find that as body weight goes up, so does RMR. This makes logical sense as a large body burns more calories at rest (as well as during activity) than a smaller body.
The following is from a study which measured RMR in some absurd number of people.
It shows clearly that as fat free mass (FFM, just another term for LBM) goes up, so does energy expenditure (this is actually measuring 24 hour TDEE but the same holds for RMR). And given that part of the weight gained during the development of obesity is LBM….
You might also notice that there is quite a bit of variation in TDEE at any given body weight so it’s not as if there isn’t variance. But as I’ll come back to below, this isn’t generally due to major differences in RMR per se.
Cause and Effect
I would note that one risk factor for becoming obese in the first place is a lower than predicted metabolic rate for bodyweight. That is, some people, BEFORE they become obese, have a lowered metabolic rate relative to what you’d expect based on their weight. So if you took two people who weighed 160 lbs and one had a resting metabolic rate of 1600 calories while the other had a resting metabolic rate of 1400 calories, the second would be at a higher risk.
This relatively lowered metabolic rate is probably due to hormones, including both lowered thyroid hormone and low nervous system output. At one point it was even stated that most forms of obesity were related to a low sympathetic nervous system output.
And, as with other involved factors, this relatively lowered RMR or TDEE would be expected to put someone at more risk for gaining weight and becoming obese. And as they do, it’s common to see nervous system output go up along with metabolic rate.
Basically, this relatively lowered metabolic rate is a cause rather than an effect. And by the time someone has become obese, this “defect” has reversed itself.
Low RMR or Low TDEE?
The point is that, outside of some major metabolic problems, you simply do not see obese individuals with exceedingly low RMR’s for their body weight. When they are measured, their RMR is always higher than lighter individuals.
Now, as I said above, RMR is only one of four components of TDEE to begin with. On average RMR usually makes up about 65-75% of TDEE in most individuals (the percentage is lower in highly trained athletes performing a ton of activity). But the others are also relevant here.
The Thermic Effect of Food (TEF) is one. Research has routinely found that the insulin resistance common to obesity can cut TEF by 50%. Now, normally TEF is estimated at about 10% of total daily calorie intake. If someone was eating 3000 calories per day, you’d expect a TEF of about 300 calories/day. When insulin resistance is present, this could be reduced to only 150 calories/day. This isn’t a huge amount to be sure but it does add up. Over one month, that 150 calories difference is 4500 total calories which is just over one pound of fat.
There is also the activity issue. As I mentioned above, there are two components of this: formal exercise and everything else. In this article series, I am talking about beginners, defined as individuals not currently involved in exercise. So the calorie burn from exercise is defined as zero.
But what about the other one, the everything else? This encompasses activities such as normal daily activities, some unconscious things like fidgeting and others. And it certainly can be reduced in obese individuals. Simply, due to the difficulties in movement that may arise as obesity develops, spontaneous daily movement may decrease. With it, so will calorie expenditure.
The point being that even if RMR is higher in the obese due to having a larger body, and even if the energy burned during activity is higher, TDEE may still be lower than expected due to a decreased TEF And reduced overall daily activity. Please note that I did not stay it would be “low” but rather “lower than expected.”
Simply, a smaller individual with a massively high activity level could still conceivably have a higher TDEE than a larger individual with less activity.
To be honest, none of this is really that important practically in terms of how I will recommend training the obese beginner. At this point I’m just trying to be comprehensive along with busting a long-held myth about “slow metabolisms”. Simply, outside of a few severe metabolic pathologies, it doesn’t exist.
The Realities of Exercise for the Obese Beginner
I mentioned obliquely above that calorie burn during exercise tends to not be enormously high no matter what you do under most situations. This tends to be especially true in the situation where someone is not well trained and has little tolerance for exercise in terms of the amount or difficulty that can be done.
To be sure, this applies to all beginning exercisers. Nobody comes out of the gate being able to tolerate a lot of exercise immediately. However, individuals carrying excess bodyweight have the additional factor of the excess bodyweight. In the initial stages, insanity like The Biggest Loser notwithstanding, this means a relatively low capacity to burn calories with exercise.
This has always actually been one of the ironies of exercise, the fact that usually the only people who can burn a lot of calories with exercise are the ones who usually don’t need it from a weight or fat loss perspective. Here I am talking about trained athletes who can easily burn 600+ calories in an hour and do that for hours at a time. If they are willing to really push they might achieve calorie burns of 900-1000 calories per hour for shorter periods of time.
In contrast, the typical average beginner might be lucky to burn 5 calories/minute during exercise, and maybe reach 300 calories in an hour. Even that still includes the calories they would have burned during nothing. So they really only burned maybe 240 calories extra. In some cases, values of 10 cal/min might be achievable for at least some amount of time. Few beginners will be able to achieve more than that for more than a few minutes at a time.
Note: I am not saying that those values are absolutes or cutoffs that nobody will ever cross. There will always be an exception and I am talking only in generalities.
I would mention that, certainly larger individuals burn more calories than smaller individuals during most forms of activity. This is just a function of being larger. At the same time, their ability to do a lot of activity initially is usually quite limited. I have had clients who were unable to walk briskly on a treadmill for more than 5 minutes without becoming fatigued. This does not provide much potential for calorie burn.
Essentially the contradiction is this: the people who need to be able to burn a lot of calories during exercise (i.e. people who want to lose weight/fat) usually can’t do it, at least not initially. In contrast, the people who can burn a lot of calories during exercise (i.e. trained athletes) usually don’t need to be able to do it for fat loss.
The Impact of Exercise on Weight Loss
All too frequently exercise is offered up as the ultimate solution to obesity. And unfortunately this claim is vastly overblown. Most studies to date simply don’t support a massive effect of exercise on weight and fat loss, at least not in terms of the total quantity that is lost. This isn’t to say it doesn’t have other benefits. But increasing the rate of weight loss is not generally one of them.
This is for a few reasons. One is that the exercise programs are generally unsupervised and the fact is that subjects aren’t as compliant as they should be. Invariably, supervised exercise studies generate better results. The arguably bigger issue is that most studies use fairly moderate amounts of activity.
And the calorie burn simply isn’t there. When studies have found a major effect on weight or fat loss, they invariably used large amounts of exercise. One I recall had the subjects doing 2 hours per day on the bike. They lost fat but had to do 12 hours per week of exercise. Doing 30 minutes three times per week just doesn’t do anything.
And you can forget about the High-Intensity Interval Training studies everybody likes to go on about. The famous Tremblay interval study only saw a few loss of a few pounds over 12 weeks. Not only is that relatively insignificant in the big picture, most beginners won’t have the tolerance to survive the workout.
Altering Diet Beats Exercise
The realities of exercise actually do have one major practical implication, one that I’ll come back to in more detail later in the series. That implication is that, initially, altering someone’s diet has a much greater chance of impacting on energy balance than adding exercise. The key word here is initially.
The reason is simply numerical. The increase energy expenditure via activity by 500 calories per day might require 50-100 minutes of moderate intensity activity. This is generally unrealistic for most people. At the same time, in the case where someone’s diet has a lot of issues, removing 500 calorie per day can be done much more easily.
Here I’m not even talking about someone going on a diet. Often simple qualitative changes to intake are all that is needed. Years ago I had a client who was consuming something like 4 full sugar sodas per day. I suggested he replace those with diet soda or water which he did. That single change along reduced his intake by 500+ calories easily and he started losing 1+ pound fat per week.
The point, again, being that initially most beginners (obese or not) will not be able to do enough exercise to significantly impact on their bodyweight. Yes, there may be other benefits of the exercise such as increased adherence, health, etc. But the calorie burn is simply too small, especially relative to what can be done with dietary modification to matter.
But the key word here is initially. And in most of the studies that used only moderate amounts of activity (generating disappointing weight loss), there was also no form of progression. The subjects started their exercise program and then just did the same thing week after week.
Not only is that not the best way to improve health or fitness, it’s not the best way to apply exercise for weight and fat loss.
Exercise Should Always be Progressed
The most basic principle of exercise is called overload. All this means is that, over time, the body has to be forced to do more work. More here can be more in terms of the total time, how often it is done, or how hard it is. You have to push the body past what it is used to and that is how you drive adaptations.
It’s also how you burn more calories over time.
Because as I said, most beginners, obese or otherwise, have an initially low tolerance for exercise. But it can improve over time. Quite in fact, it always does improve, usually fairly quickly. If there is one “advantage” of being a beginner, it’s that you see faster progress than if you were more highly trained.
That rapid set of improvement has its own set of benefits in terms of adherence, a topic I’ll come back to later in the series. My point being that, to one degree or another the training should and must progress either in terms of volume (duration), frequency (times per week) or intensity (difficulty). Or all three. I’ll discuss the practicalities of this later, just bear with me for now.
Studies that have done this have generated significant fat loss. One that comes to mind progressed it’s subjects, in a supervised exercise program, from just over 100 calories/day of exercise initially to nearly 600 calories/day. But it did it gradually over 6 months which is key. The subjects started with a small amount of easily tolerated exercise and as they got fitter they did more.
And since it happened over such a long time frame, by the time they were burning that many calories, they probably never really felt overwhelmed by it. That is, it wasn’t as if they were jumped into a gruelling 600 calorie/day exercise program right off the bat. That’s how you break someone and chase them away from exercise. They started slow and built up. There is a lesson here.
- 3 Reasons Diets Don’t Cause More Weight Loss in the Obese
- EPOC: Excess Post-Exercise Oxygen Consumption After Exercise
- Dissecting the Energy Needs of the Body
- A 45-Minute Vigorous Exercise Bout Increases Metabolic Rate for 14 Hours
- The 3500 Calorie Rule