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Background: This question was prompted by a few comments from user:michael Quote 1

Quote 2

Reading through a recent New York Times article related to the subject prompted me to prove further into the topic of metabolism and how it is affected by exercise and weight loss.


"The biggest loser" is a show where contestants compete against each other to lost weight the fastest. It has come under a lot of criticism for "fat shaming" and there are many controversies surrounding the show. In a recent New York times article there was evidence put forward that some people just cannot keep weight off due to the changes in metabolism.

In the article, Dr. Hall, an expert on metabolism at the National Institute of Diabetes and Digestive and Kidney Diseases, which is part of the National Institutes of Health is quoted:

It has to do with resting metabolism, which determines how many calories a person burns when at rest. When the show began, the contestants, though hugely overweight, had normal metabolisms for their size, meaning they were burning a normal number of calories for people of their weight. When it ended, their metabolisms had slowed radically and their bodies were not burning enough calories to maintain their thinner sizes.

Researchers knew that just about anyone who deliberately loses weight — even if they start at a normal weight or even underweight — will have a slower metabolism when the diet ends. So they were not surprised to see that “The Biggest Loser” contestants had slow metabolisms when the show ended.

...As the years went by and the numbers on the scale climbed, the contestants’ metabolisms did not recover. They became even slower, and the pounds kept piling on. It was as if their bodies were intensifying their effort to pull the contestants back to their original weight.

Looking online, there are articles that state that exercise can improve your MR and even your BMR:

And even the odd article that conclused the opposite of the finding of the NYT! Svetkey LP, Stevens VJ, Brantley PJ, et al. (2008) finds,

Conclusions: The majority of individuals who successfully completed an initial behavioural weight loss program maintained a weight below their initial level. Monthly brief personal contact provided modest benefit in sustaining weight loss, whereas an interactive technology-based intervention provided early but transient benefit.


Question:

Is weight regain following a diet inevitable due to changes in metabolism or can a sustained better lifestyle which includes exercise change your BMR to bring it to normal levels for your reduced weight?

Bonus: Is The Biggest Loser a indicator of a larger (forgive the pun) problem with losing weight or is the show a outlier due to its nature?

Notes

Please do not focus on why the weight was gained in the first place. There are many reasons as to why Americans have a greater level of obesity but this question does not want to discuss that.

Please give full sources for all statements made in your answers, and clearly indicate what you believe to be common knowledge or your (or others) opinion. Bonus points for citing like I have using the description of a link.

Edit: This article has been discussed further on reddit's r/fitness https://www.reddit.com/r/Fitness/comments/4hhgjk/new_york_times_article_summarizing_longitudinal/

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  • +1 for interesting question. As someone who's trying to lose weight and read the Biggest Loser article I am curious also about this. Is this something that typically happens in extreme weight loss (300lbs+ to ~200lbs within a really short amount of time) like the contestants on the show or does this also happen to people on a normal weight loss program (1-2lbs/wk)? If I'm not mistaken they work out on low calories for 8 hours a day, correct? – Yousend May 18 '16 at 12:06
  • @akadian Only information I can find is from Wikipedia which states "The weight-loss regimen used in the show—severe caloric restriction combined with up to six hours a day of strenuous exercise" – John May 18 '16 at 12:19
  • @akadian bit more digging has come up with this article which details the regime in full detail: onlinelibrary.wiley.com/doi/10.1002/oby.20065/full – John May 19 '16 at 9:41
  • Nothing is inevitable. My point is that no one has ever shown in a randomized clinical setting that maintaining weight loss is possible for the vast majority of people. That doesn't mean it isn't possible; it just means it hasn't been done, and if you think you know how to do it, you are probably fooling yourself. – michael May 19 '16 at 15:25
  • ncbi.nlm.nih.gov/pubmed/23747584 "Participants achieved significant weight losses at post-treatment, with no significant weight regain at six-month or 18-month follow-up." – John May 19 '16 at 15:32
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Warning, wall of text incoming. Sorry, but there's a lot to look into. TL;DR at the end.


Let's first take a look at what seems to influence (base) metabolic rate the most. For starters, when we look across species, there appears to be a neat relation between the average mass of a subject in that species and its metabolic rate. A linear relation, in fact, between the metabolic rate and body mass to the power of 3/4. This is known as Kleiber's law. The slope varies a bit among single-celled organisms and cold- and warm-blooded animals, but in general the relation holds within each group.

Given that metabolic rate scales with body mass among animals, perhaps it isn't far-fetched to expect it also will for subjects within a species, including humans. Here is a fascinating study digging into what correlates with basal metabolic rate (BMR) for people: http://ajcn.nutrition.org/content/82/5/941.full (Factors influencing variation in basal metabolic rate include fat-free mass, fat mass, age, and circulating thyroxine but not sex, circulating leptin, or triiodothyronine1,2,3; The American Journal of Clinical Nutrition).

Within-subject effects, meaning within the same person, accounted for a variability of only 2%, with 0.5% being analytic error. Of more interest are the between-subject effects, looking at what are the best predictors for BMR. We find the following percentages for explaining BMR:

  • 63% for fat-free mass (FFM)
  • 6% for fat mass (FM)
  • 2% age
  • 26% unexplained

The last portion was found not to be explained by circulating leptin (the hormone driving satiety) or triiodothyronine (a thyroid hormone). Interestingly, thyroxine (another thyroid hormone) showed no relation to the variance for women but did account for a whopping 25% of the residual variance in men.

This means that there's more to our BMR than FFM and FM, but it can be seen that FFM is one of the biggest factors and FM isn't negligible. So there's some conclusions some folks aren't gonna like.

The first is that fat-free mass is important and height plays an important role in that. Evidently people with the same height can have an important variation in FFM depending on things such as bone density and muscularity. This supports the notion that strength training and hypertrophy can be useful in supporting sustained weight reduction, since it would raise BMR. However, the amount of muscle that can realistically be gained without the use of anabolics isn't without limits. So while strength training can be a nice boost for an individual, it simply isn't going to make up for the difference in FFM between two people who are at respectively 60 kg and 90 kg at the same body fat percentage. You can expect taller people to be able to get away with eating a lot more than shorter people for maintaining a similar body fat percentage (conversely, they may also require a lot more to build muscle when training).

Secondly, fat mass is significant at 6% but not so dramatic that it is going to grind your metabolism to a halt when significant fat loss occurs, which is what some people claim. This makes sense from a biological point of view. Maintaining lean body mass including bones, muscle, internal organs, skin and more is metabolically expensive. It wouldn't make sense for the retention of fat mass to be particularly metabolically expensive because that would make it a pretty poor source of energy, which is its primary function. That'd be like a very significant factor for a car's fuel consumption being the fuel present (it has some bearing due to weight but not that much) or it using fuel when it's just standing in the garage.

Third, circulating hormones, to the extent of the ones investigated (which are significant for metabolic rate) aren't gonna be the make-or-break deal. People diagnosed with actual hypothyroidism are going to see significant effects regarding fat loss and gain, but in the presence of a normal functioning of the thyroid and hormonal system, the frequently heard claim that someone just can't lose weight or gains too easy due to hormones, when they've never had any tests done in that regard, must be seen as an excuse. Sorry folks, but you can't blame medical issues without evidence of such issues having been established in you, and I'm afraid it has been shown time and time again we are all very adept at lying to ourselves.

Finally, there are other factors at play which could be significant and might have some bearing on why with two people of similar stature one can sometimes seemingly eat at will and the other will have a hard time keeping body weight down. But since there can be too many confounding factors there and this would lead away from the question at hand, we'll continue with what can be quantified.


So as weight is reduced by fat loss, this will lead to some drop in BMR directly related to fat mass but not enough to warrant claims that BMR dramatically slows, enough to cause a major rebound effect when after a diet one resumes what should be a total daily energy expenditure (TDEE) consumption. So does weight loss in some other way lower BMR?

Here we arrive at the dreaded "starvation mode". Many people believe that as less calories are consumed, the body in reaction will slow down metabolic processes and/or redistribute priorities to prolong functioning in the face of what could be a crisis. It certainly doesn't seem impossible, because there's quite a difference in peak performance and "adequate" performance. However, it's one of those unique things for which I wish I had a name. One of those ideas that originate somewhere, from a source that at that time may very well be reliable but might be incomplete, becomes invalid in the face of newer evidence or just gets outright misinterpreted. The simple version becomes popular, spreads, and soon its frequent repetition cements it in the mind of the general population as "common knowledge". But as new information becomes available and those on the forefront of gathering it become frustrated with the dissemination of the old "common knowledge", they begin labeling it as a myth and will provide counter-arguments. Since people like to feel clever and on the cutting edge, now the "myth" gets vehemently attacked, much to the annoyance of those who lived by it and now either feel lied to, misled or personally under attack. Prepare to see a lot of such swinging pendulums in nutrition and exercise ("calories in/calories out", "a calorie is a calorie", nutrition timing, barbells->machines->barbells).

So IS it a myth? First its origin. The source seems to be mostly the Minnesota Starvation Experiment (https://en.wikipedia.org/wiki/Minnesota_Starvation_Experiment). In the experiment it was found that physiologic processes which are important indicators for BMR were indeed lowered. However, the subjects in the study were actually starving, not on some manageable fat-loss diet. A nice counter-point comes from this study: https://www.ncbi.nlm.nih.gov/pubmed/11010936 (full text: http://ajcn.nutrition.org/content/72/4/946.long, Energy metabolism after 2 y of energy restriction: the biosphere 2 experiment, Am J Clin Nutr. 2000 Oct;72(4):946-53). When it comes to human studies it doesn't get much better than locking them up in a biosphere for 2 years when you're staying on the legal side of things. The study concludes that there is an effect, but let's look at the magnitude. Weight loss on average was 15% of body mass, and most of that was from fat loss because while diet was restricted, it wasn't nutritionally poor. The average response in TDEE was a 180 kcal reduction. That isn't much to start with. 60 kcal were explained by the loss of body mass itself (FFM and FM), 65 kcal from a reduction in fidgeting and 55 kcal dismissed as statistically insignificant.

The idea that BMR will be seriously lowered as the result of a diet, and especially the concept of starvation mode, have been increasingly labelled as myths recently. While there is some truth to it, enough nails have been driven into that coffin to conclude for now that this is not what causes so many people to rebound after a diet.


So what was going on in The Biggest Loser? I figure, two things.

First of all, calorie restriction for the people on this show, being encouraged to lose as much weight as possible, as fast as possible, was closer to the actual Minnesota experiment numbers than what should be considered a sane and sustainable diet. Dr. Hall who is quoted from the interview in the question has published an article about the show which says as much (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3660472/). Quite importantly, the dramatic approach to weight loss doesn't just affect fat. Some lean body mass would have been lost as well, notably muscle, which we've previously seen would affect metabolic rate a lot more. So now we've got people who've lost fat as well as useful lean body mass, have a lowered metabolic rate and are then released from their harsh crash diet. Two guesses as to what's going to happen.

This brings us to the second point: a terrible misconception about "diet" rooted in ideas that should by all means be outdated. You've seen it in the magazines... The "banana diet", all the "detox" diets, low fat diets, recently the keto diet. People have been led to believe that a diet is something you do for a limited and uncomfortable time, until the situation has been "fixed" and the diet can then be ended. The problem is that it wasn't a momentary lapse in judgement that caused anyone to become overweight, it were usually sustained poor nutritional habits that caused weight gain, probably imperceptible on a scale of weeks or even months, that accumulated over time. The right approach to a "diet" is to establish better habits, at a scaled-down version of what can be done after reduction in body fat has been completed so that the new weight can be maintained. I'm not gonna dig up further studies but it has been observed that diets, in this sense, are in fact an indicator of future weight gain. Also, the harsher a diet, the more difficult it is going to be to sustain it for any significant time. When you are pitting survival instincts honed by hundreds of millions of years of evolution against cognitive processes which are toddlers in comparison, your "willpower" ain't gonna win.

Dr. Hall also shows in the above article that if a more moderate caloric deficit had been maintained coupled with exercise, over a longer period of time, not only would the same weight loss eventually have been reached, it would have been so while maintaining lean body mass, leaving the contestants in better shape and better equipped to maintain their new body weight.

In that sense, yes, the program is an extension of a much larger problem: that diets are still approached in this crash-and-burn manner rather than seen as a gradual change towards better, sustainable habits. It peddles to the impatience of people in wanting results immediately and the fact that a plan which takes years to complete is very daunting. I guess following someone for 3 years while they lose 0.25 kg per week wouldn't make for very thrilling television, but that person would make excellent progress when starting off obese.


TL;DR

  • Fat-free body mass is the main contributor to basal metabolic rate.
  • Fat mass also contributes to BMR but to a much lesser extent.
  • "Starvation mode" won't occur from simple caloric restriction, unless you are actually starving yourself.
  • BMR won't slow down dramatically as a result of fat loss or a moderate caloric deficit.
  • BMR can slow down quite a bit as a result of a drastic caloric deficit, which may at least in part be due to losses of lean body mass.
  • Weight can be lost and kept off with a proper approach.
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  • Great answer! Some tidying edits may come your way as suggestions from me. Only thing missing for me was explanations or suggestions why the tv show contestants all gained so much and had their BMR slowed so much beyond just implying that they had lose some LBM. – John May 19 '16 at 7:00
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    @JJosaur A study referenced by Dr. Hall in his article is this: ncbi.nlm.nih.gov/pmc/articles/PMC3387402. It shows dramatic decrease of resting metabolic rate after substantial weight loss where fat-free mass was preserved as much as possible, beyond what would be expected from changes in body mass alone. This persists after ceasing the caloric deficit. The study speculates on causes but no definite conclusion can be drawn. For now I think it's best to conclude a slow approach to weight loss is more prudent. – G_H May 19 '16 at 7:51
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    It kind of makes sense looking at it from Selye's theories on stress and adaptation. The stress: severe caloric restriction. The response: using fat to maintain biological function. The adaptation: lowering metabolic rate to rebuild fat stores and minimize impact of a repetition of the stress, to prolong survival at the cost of optimal performance. When you think about it, a lower body fat % is an artificial way of appearing more muscular. We think a 6-pack looks neat, but for our body it's "code red, emergency rations depleted". – G_H May 19 '16 at 8:08
  • Missed reading that article in your answer, its fascinating! It's amazing how many medical studies and meta-analyses have spun off from this TV show. – John May 19 '16 at 8:34
  • @JJosaur It wasn't really in the article in the answer, it was cited as a reference. If it seems useful the answer could be made community wiki. – G_H May 19 '16 at 8:39
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I've unwittingly done a long term experiment on myself. The answer, in my case at least, is yes. I used to weigh about 63 kg and eat about 3000 kcal/day a decade ago. Today I eat about 3800 Kcal/day and weigh 54 kg. The main change is that I increased my exercise effort, it used to be about 20 minutes of running 3 times per week, while now it is one hour of running, 5 times per week.

I never aimed to lose weight, my aim was to improve my fitness. I did not reduce the calorie intake, I did the opposite as my thinking was that to build up fitness requires getting in more calories and nutrients. Also, 63 kg isn't all that heavy anyway, so losing weight was not something that crossed my mind. And that probably helped me to drastically improve my fitness and as a side effect lose weight. Had I reduced my calorie intake, I would probably have struggled with the effort to increase the exercise time and failed to reach my fitness goal.

Now consider the initial state where I was at 63 kg and the final state where I am at 54 kg. In the initial state my weight was stable I was not gaining or lowing weight on the long term. So, there was an equilibrium between energy intake and energy used. And this was also a stable equilibrium, particularly the expended energy would fluctuate, but my weight was still stable. This is presumably due to feedback mechanisms that adjust the metabolic rate in response to fat cells getting emptier or more filled. That equilibrium was reached at energy intake = energy use = 3000 Kcal/day.

In the final state I am now at, a different equilibrium is reached at a higher level: energy intake = energy use = 3800 Kcal. The weight of 54 kg is irrelevant, other than the fact that this is constant indicating that I'm indeed at equilibrium. The only reason why this change happened was because I build up my fitness to the point I can exercise a lot harder. I burn about 700 Kcal a day now, which is more than 20% of the calorie intake. In the old equilibrium state I burned a factor of 5 less, this was only about 5% of the energy intake.

Why did I lose weight? We can in principle invoke all the relevant biochemistry here and ultimately the long term changes in the fat reserves due to the change in energy use and the change in energy intake. But i.m.o. this is not the right way to analyze the problem. If you slow down and stop your car at a red traffic light, you do so because you are programmed to stick to the traffic rules. But in principle you could explain what happened by analyzing all the processes at the molecular level and then invoke signals send through your nerves to your feet that then hit the brakes and how that then causes the car to slow down.

That's all correct, but it's also mostly irrelevant because the system was designed to work that way. This means that had the car design been different and had we evolved in a different way, we would still have had to resort to traffic rules, and we would have ended up implementing the same process where you need to slow down or stop, but it would be implemented in a different way.

Similarly, I believe that I lost weight because by exercising a lot more, my body executed a different algorithm for energy management with the specific goal of making running easier. This involves both becoming fitter and losing weight. Hundreds of millions of years of evolution has led to a body that uses such algorithms for survival. Animals don't start to exercise a lot more for fun, if they end up expending a lot more energy then that means they have to do this to get the food they need. The body has evolved to maximize the survival probability, so when this happens it will factor in this new situation and adjust the optimal strategy. The amount of fat reserves will then be adjusted. The metabolic rate will be adjusted until the desired optimal state given the amount of exercise, energy and nutrient intake, is reached.

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4

Maintaining Weight Loss: Who is the biggest loser?

Introduction

There is a lot to consider when examining the impact of changing lifestyle in the short or long term with the goal of losing weight. In my answer I will compare the findings of the longitudinal study of TBL against similar clinical trials that assess the success of long term weight loss and its attbutation to changes in basic metabolic rate (BMR).

This question focuses on the use of the TV show “The Biggest Loser” (TBL) which debut in October 2004. In the show, obese, contestants compete to win a significant cash prize by losing the highest percentage of weight relative to their initial weight (Wikipedia, 2016).

TBL: Weight loss regimen: Risks and Criticism

First, to fully understand what is happening to the bodies and minds of the contestants in TBL prior to finishing the show, I will explore some of the criticisms of TBL over its broadcast history. The show starts with a disclaimer, which states:

“Our contestants were supervised by doctors while participating in the show, and their diet and exercise regimen was tailored to their medical status and their specific needs. Consult with your own doctor before embarking on any diet or exercise program.”

Despite this claim of supervision by a certified medical professional, all contestants are required to sign a waiver which states:

"…no warranty, representation or guarantee has been made as to the qualifications or credentials of the medical professionals who examine me or perform any procedures on me in connection with my participation in the series, or their ability to diagnose medical conditions that may affect my fitness to participate in the series". (Pitney, 2010)

The exploitative nature of the show is attacked by Dr Charles Bruant (Edward, 2016), director of the Michigan Metabolomics and Obesity Center, who states:

"I’m waiting for the first person to have a heart attack. I have had some patients who want to [follow the show's regimen], and I counsel them against it. I think the show is so exploitative. They are taking poor people who have severe weight problems whose real focus is trying to win the quarter-million dollars." (Edward, 2016)

Dr. Bruant’s asserts that the mental strain placed on the contestants due to the 'competition' aspect of the show leads to significant mental trauma is reaffirmed by information supplied by the contestants themselves.

Ryan C. Benson, the winner of the program’s first season (Wikipedia, 2016), publicly admitted that "[I] dropped some of the weight by fasting and dehydrating myself to the point that I was urinating blood". Since the show completed, Benson has regained almost all of his weight (Edward, 2016).

In 2009, Kai Hibbard (runner-up from the third season) told The New York Times that "contestants would drink as little water as possible in the 24 hours before a weigh-in" and would "work out in as much clothing as possible" when the cameras were off. She further stated that two weeks after the show ended, she had regained about 31 pounds, mostly from staying hydrated (Edward, 2016).

Next, In a June 2010 interview, Hibbard (another contestant) said, "I do still struggle [with an eating disorder]. I do. My husband says I’m still afraid of food... I’m still pretty messed up from the show.” (Poretsky, 2016).

It is clear that TBL is a harmful show for those competing and this has had a significant effect on their mental health, this trauma culminates just before they move into a self-lead period sustaining their weight loss. It is clear that, for some contestants, the psychological trauma of taking part in the competition has directly affected their ability to sustain a healthy weight in the long term but this is not true for all those involved.

The triggers for many weight gain relapses are known to be linked to depression spirals from self-image hate. Food is treated as a comfort for these people who are disgusted when they see themselves leading to a compulsion to eat to feel emotionally 'better'. An examination of the psychology of the show (Domoff SE, et al., 2012) concluded that Participants in The Biggest Loser competition had significantly higher levels of dislike of overweight individuals and more strongly believed that weight is controllable after the exposure which could lead to future depression and faster rebound to original weight.

TBL: Longitudinal Study

In 2016, the results of a long term study by the US National Institute of Health (NIH) were released which documented the weight gain and loss of contestants in Episode 8 (in which Danny Cahill achieved the show's record-setting loss). The study found that most of the 16 contestants involved regained their weight, and in some cases, gained more, than before they entered the contest. (Kolata, 2016).

The New York Times article continues to assert the reasoning behind the general trend of TBL contestants to regain lost weight as being primarily linked to a slowing metabolism, meaning they burn fewer calories at rest then expected for a person of their current size.

The article continues to explain how dieting affects metabolism:

Researchers knew that just about anyone who deliberately loses weight — even if they start at a normal weight or even underweight — will have a slower metabolism when the diet ends. So they were not surprised to see that “The Biggest Loser” contestants had slow metabolisms when the show ended.

However, rather than the metabolisms of the contestants recovering to match that of someone of their current size, they instead plummeted as if their bodies were fighting to put the weight back on. In one extreme case Mr. Cahill who gained 100lbs since the show has to eat 800 calories less than a man of his current size to maintain his weight. (Kolata, 2016)

The article continues, quoting Dr. Michael Schwartz, an obesity and diabetes researcher who is a professor of medicine at the University of Washington:

“The key point is that you can be on TV, you can lose enormous amounts of weight, you can go on for six years, but you can’t get away from a basic biological reality,” ... “As long as you are below your initial weight, your body is going to try to get you back.” (Kolata, 2016)

Next, Dr. David Ludwig, the director of the New Balance Foundation Obesity Prevention Center at Boston Children’s Hospital, who was not involved in the show is quoted:

“This is a subset of the most successful [dieters]"...“If they don’t show a return to normal in metabolism, what hope is there for the rest of us?”…“that shouldn’t be interpreted to mean we are doomed to battle our biology or remain fat. It means we need to explore other approaches.” (Kolata, 2016)

The article concludes that for the vast majority of TBL contestants, all of them have a significant fight with their metabolism following the show.

The shock-and-awe tactics of the show to strip the weight off fast could be potentially causing a substantial deficit in leptin levels for a sustained period, and that lead to a higher baseline hunger level. The article (Kolata, 2016) supports this theory somewhat, referencing a one-year study similar to TBL format funded by Australia’s National Health and Medical Research Council (Sumithran, Prendergast, Delbridge, Purcell, Shulkes, Kriketos and Proietto, 2011), Dr. Joseph Proietto of the University of Melbourne and his colleagues recruited 50 overweight people who agreed to consume just 550 calories a day for eight or nine weeks. They lost an average of nearly 30 pounds, but over the next year the weight was regained. Dr. Proietto and his colleagues looked at leptin and four other hormones that satiate people. Levels of most of them fell in their study subjects. They also looked at a hormone that makes people want to eat. Its level rose.

“What was surprising was what a coordinated effect it is,”...“The body puts multiple mechanisms in place to get you back to your weight. The only way to maintain weight loss is to be hungry all the time. We desperately need agents that will suppress hunger and that are safe with long-term use.” (Sumithran, Prendergast, Delbridge, Purcell, Shulkes, Kriketos and Proietto, 2011)

In the aforementioned article (Kolata, 2016), Dr. Hall, an expert on metabolism at the National Institute of Diabetes and Digestive and Kidney Diseases, is quoted for stating that the researchers involved in the show knew “[the contestants] will have a slower metabolism when the diet ends”.

Following the show, Dr. Hall released an article that fully details the magnitude of dietary restriction and exercise intervention that the contestants experience. The findings of “Diet versus exercise in “the biggest loser” weight loss competition” (Hall, 2013) concurs with many of the points previously discussed here with respect to the contestants maintaining and continuing to attempt a diet that was known to not sustainable in the long term. Using simulation, Dr. Hall showed that the weight loss that contestants craved could be achieved by less drastic methods, thought the time needed to achieve and maintain their goals successfully would be in the domain of years and not months as was suggested by the competition.

Other Relevant Studies

Those who are successful at maintaining weight lost often experience positive associations with their new, lower weight. On TBL it is clear that negative associations with food can and have developed which might raise the probability of longer term relapse. The psychological symptoms for those who have been successful at long term maintenance of weight loss (Klem et al., 1998) are those of positive general mood and self-confidence, with many involved in the study stating that is was easier to keep the weight off. In this study, it was entirely down to those involved to decide how much weight they wanted to lose and at what rate.

Next, the body takes many years to respond to the change needs it has placed upon it. A recent study (Wing and Hill, 2001) found that the period that it takes for your body to adapt to new diet and exercise regimes is longer that that expected; the chances of long term success of keeping weight lost off also greatly increase after keeping weight off for more than 2 years due to continued adherence to diet and exercise strategies, low levels of depression and dis-inhibition, and medical triggers. This may go some way to explaining the reasons for relapse when the average cycle time for a diet and sustain is 1 year.

A study of resting metabolic rate (RMR) by the National Weight Control Registry (Wyatt, 1999) of those who have reduced their weight concluded that in at least some reduced-obese individuals there does not seem to be a permanent obligatory reduction in RMR beyond the expected reduction for a reduced lean mass through rapid dieting. This is supported by additional analyses of resting metabolic rates among formerly obese subjects (Astrup, 1999); this analysis concludes that formerly obese subjects had a 3-5% lower mean relative RMR than control subjects; the difference could be explained by a low RMR being more frequent among the formerly obese subjects than among the control subjects. Whether the cause of the low RMR is genetic or acquired, the existence of a low RMR is likely to contribute to the high rate of weight regain in formerly obese persons.

The metabolic rate is known to scale with body mass, which can be broken down into fat-free-mass and fat mass. Studies (Weinsier, Schutz and Bracco, 1992; Cunningham JJ, 1991; Fukagawa et al., 1996) agree that changes to the amount of fat-free-mass a person has directly affects their metabolism but the level which other factors affect metabolism: fat mass (FM), gender, age and hormone levels (Leptin, triiodothyrionine (T3), and thyroxine (T4)) is still not completely understood. A study by the American Society for Clinical Nutrition (Johnstone et al., 2005) investigated the effects of these secondary factors, concluding that both FFM and FM are significant contributors to the basal metabolic rate. However, it also found that leptin, gender and T3 levels are not statistically significant in determining the BMR.

One important factor to consider is the research conducted as part of the Minnesota Starvation Experiment (Keys and Drummond, 1950). A follow up study published in the American Journal for Clinical Nutrition re-created the MSE but in an improved environment, utilising the Biosphere facility to investigate if the findings of the MSE, that during starvation the body drastically changes its metabolism, were accurate. The results of this study (Weyer et al., 2000) were that six months after exit and return to a normal diet, body weight had increased to pre-entry levels; however, adjusted metabolism was still significantly lower than in control subjects.

The study by Weyer et al. concluded that in lean humans metabolism adaptively decreases to account for “Starvation Mode” and in response to sustained (>5 years) energy restriction. On average, those involved in the biosphere study lost 15% of body mass on a nutritionally rich diet which points to fat-mass (FM) being lost and not significantly lowered levels of fat-free-mass (FFM). However, it is also worth noting that the average change described to BMR was 180kcal, broken down by the study to indicate that the reduction attributed to changes in FM and FFM were equal to those attributed from a reduction in fidgeting. (~60kcal ea.)

Effect of Exercise on Changing Metabolism

Strength training has shown, especially for men, to contribute to a rapid improvement in RMR (resting metabolic rate) (LEMMER et al., 2001). An earlier study of 50-65-yr-old men also agrees with these findings that the BMR can be improved with resistance exercise (Pratley, 1994). A 2001 review concludes that “More recent research demonstrates that resistance training may positively affect risk factors such as … resting metabolic rate … which are associated with diabetes, heart disease, and cancer” (Winett and Carpinelli, 2001). In addition to the findings that resistance exercise improves RMR, cardiovascular training has shown to be effective at maintaining weight loss (Pollock et al., 1998).

However, other analysis of TBL show indicate that exercise alone would not have a significant impact on RMR compared to that of changes to diet, an analysis of the show simulated that exercise alone was predicted to decrease RMR by only 1% versus baseline whereas dietary changes alone was predicted to suppress RMR by 25%.

Conclusions (TL;DR)

Examining "The Biggest Loser" (TBL) it is clear that the contestants are taking part in a weight loss exercise program that makes it harder to maintain long term. The detrimental physiological and physical impact on the contestant’s bodies sets them up for long term failure. This matches the 6 month re-test data that was gathered on the RMR and weight of those who took part.

Studies have found that by completing a doctor-recommended weight loss regime that is driven by the individual (as observed in the national weight control registry) that sustained weight loss/lost is more likely to prevail. Pairing a sensible weight-loss/maintenance program with resistance exercise can help the body in bringing the BMR back to normal levels for a person’s build following a diet, provided that there has not been significant fat-free mass (FFM) lost.

TBL's target market is those who subscribe to the “all-or-nothing” principle of dieting that became popular after the millennium. With contestants providing entertainment through their extreme ‘journey’ viewers are sucked in to watching the show. One can assume If the weight loss was 0.5kg per week with 1 hour of exercise per day, instead of its current format, many would not tune in.

TBL feeds the growing trend of “fad diets” which promise huge results in very little time, often misrepresenting facts to sell a product or service to appeal to modern expectations of immediate gratification. For real, sustainable long-term weight loss the conclusion is a simple one. Sensible weight loss targets combined with a mild 10-20% calorific deficit and regular varied exercise will lead to sustained weight loss; post-diet, balancing exercise and diet will lead to an easy weight sustain.

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