The Biggest Loser Study: Overrated???
As many know, I now specialize in treating obesity. In the last couple of years, another physician started selling a book promoting fasting. Within the book are accusations that calorie restriction hurts people, a source he leans on to make this argument is the "biggest loser study." This accusation has been in the back of my mind for a while now. But I have not been able to put a finger on exactly why it is wrong. What specifically is wrong? How was it that I even used calorie restriction to lose a good 80lbs lbs (the last 20 using nutritional ketosis), yet my metabolic rate is normal? I think I now have a better grasp of the discrepancies. So here we go...
Please keep in mind, I believe in "adaptive metabolic changes" in response to weight loss. I write this article to look at whether the "biggest loser study" can be used to make the argument one method (like fasting) is better than calorie restriction. Or really is it that all methods are the same; that really metabolic changes are due to the actual weight loss/loss of fat mass (usually more than 10%) not due to the way/method in which a person loses weight (eg calorie restriction, fasting, keto, etc).
Two studies evaluated these contestants:
The 1st: evaluated them at them from day 1 of the competition to week 30.
The 2nd: evaluated them out to 6 years beyond the end of the competition.
Johannsen DL, et al. JCEM 2012;97:2489‐96.
N= 16 contestants
Average baseline BMI = 49.4
7 males, 9 women
They exercised 90min a day 6 days a week at a vigorous intensity
All consumed about 70% of their baseline requirements.
Each contestant had different metabolic measurements taken, each value point was monitored through time.
***(Truthfully, I could probably stop here since just looking at this study's methods we know this is not a study comparing different types of diets; this study looks at people with Class III obesity and how their bodies reacted to losing a massive amount of weight in a relatively short amount of time WHILE ALSO undergoing a vigorous exercise routine. But I've put too much time into this so let's keep going.)***
By week 30: Average weight went from 328lbs to 199.7lbs
(ie the ave wt loss was ~128lbs over ~7 months)
- At just 7 months the average weight loss was 38.6% (~40%) weight loss. Note this is the average some lost more!
Gastric bypass surgery MAY lead to a weight loss of 60-80% over a 12 to even an 18month period
Gastric sleeve may lose 60 to 70%over a 12-18 month period
- In other words, the contestant achieved a greater weight loss than your average surgical patient, in just 7 months) - they had HUGE losses, losses we really have never seen in medicine before!
- So is it really fair to compare these contestants to anyone else??? Should this study only be one more small study (small in that it only evaluated 16 ppl) supporting the idea of metabolic adaption, or can it be used to compare methods of weight loss?
When they remeasured the RMR(resting metabolic rate):
First, we need to review RMR:
- Resting Metabolic Rate: basically it is the calories burned in a day doing absolutely nothing; no movement, no chewing, no digestion, not breathing hard. Basically the energy it would take to stay alive while fasting and sitting absolutely still for 24 hours.
- We have found that RMR is naturally going to decrease with weight loss, there is even a calculation made to adjust for differences in different peoples amount of fat and fat free mass to calculate, in theory, what there RMR is. Granted one can also actually do tests on an individual to find their specific RMR.
The potential problem with this equation: the equation used was discovered using data comparing different WEIGHT NEUTRAL people of different BMIs and different lean body masses. Weight neutral, meaning the people used to create this equation were not people who had undergone a recent weight loss, like these contestants.
The equation to calculate "predicted" RMR:
RMR predicted (Cal/day) = 1,001 + 21.2 X FFM(kg) +1.4 X FM(kg) - 7.1 X age(yr) + 276 X sex(F=0, M=1).
-I don't think a calculation made to predict RMR in WEIGHT NEUTRAL ppl should be applied to people who are now biologically different due to a significant weight loss. And not only did they lose weight, these contestants lost a significant amount of weight never really seen before in a short amount of time WHILE also undergoing an extensive strenuous exercise routine.
- The way I see it, using this equation is a study flaw. It's comparing apples to oranges; sure they are all fruit (humans), but they are different biologically speaking.
-If the biggest loser study had calculated each individual's RMR using a standard method like indirect calorimetry (not just some plug and chug generalized equation) and compared those results to another group's RMR who lost a similar amount of weight via another method (like fasting or surgery or calorie restriction) , then this study could be used to discuss the pros and cons of different methods. As this later type of study would now be comparing navel orange to valencia oranges....ie comparing endpoints after a significant weight loss in people who used different methods to lose that weight. But no, this study is looking at is the existence of our bodies ability to change it's metabolic rate, it is in no way evaluating if one method will have a different level of metabolic adaption compared to another method.
- More simply put it is not evaluating if people lost 40%body weight in 7 months will they have less of a metabolic adaption using fasting compared to calorie restriction. I have never seen such a study, if you have PLEASE send me it!
- At 30 weeks: average weight loss at that point was ~128lbs
- At 6 years: they gained about 70% of weight back (80% of that was fat), but there was a great deal in variation in amount regained from contestant to contestant...meaning there was variability in % of weight regained when comparing the individuals.
- At 6 years the fat free mass remained fairly stable (166lbs at baseline to 154lbs)
- RMR was
- 2,600Cals at baseline (prediction equation would have guessed the RMR would have been 2,577)
- 1,903 at 6 years (predicted would have been 2,403)
- 500 Cals less.
- ***So yes, this study supports the idea of metabolic adaptions that can occur with a significant weight loss, and that adaption might not reverse despite a significant weight regain towards baseline. But still not quite sure how this study supports it was the calorie restriction alone that caused the adaption. Especially considering other evidence showing it was the physical loss of fat mass and even possibly the extensive exercise regimen.***
- at baseline was 3,804Cal/day (ave wt 328.3lbs)
- at year 6 was 3,429 Cal/day (ave wt 290.1lbs)
-at baseline RMR was 2,607 and TEE 3,804
-at 30 weeks RMR was 1,996 and TEE 3,002
-at 6 years their RMR was 1900 but TEE was 3,429???
Very strange: as their RMR went down there TEE went down but then up???
Anyway... let's go to other issues:
Difference in methodology used to calculate RMR at 30 weeks and 6 years:
A quote from the study: "We cannot rule out the possibility that the original Max II cart became more accurate at the time of testing compared with 6 years earlier, but this seems unlikely."
- Kind of a bummer they couldn't just use the same method.
It would have been nice to know more details about the variability seen between the contestants. I was not able to find a published list showing each individuals specific changes over time. I imagine for privacy reasons.
- For example the RMR measured at 6 years was 1,902 on AVERAGE, the variability was +/- 466. 466 is a lot of calories. Could it be the individual difference in genetics, maybe some of the contestants had more of a metabolic adaption compared to others??? If so this study can not be generalized to the general public, but more specific to someone of a certain genotype who under went losing so much weight so quickly while under strenuous physical activity.
This study does support the idea of "metabolic adaption." However I don't see anything in this study that points to calorie restriction as being the culprit for the change.
- Speakers go around saying the contestant were "metabolic handicapped," but at what point?? I'm not sure a difference in about 170 Cals is a handicap?? If anything I would say a weight neutral women standing at 5'0'' is metabolically handicapped. For her entire life, and no matter what her weight is her RMR will always be lower than the average height person. Versus yes, when they regained the weight to have an RMR of 1900 at a BMI of 42, I might have been able to jump on board describing this as a metabolic handicap, but their TEE was 3,429Cal/day at year 6!?! Maybe we should more say they are hindered or have it difficult; I might reserve the use of term handicapped.
Can this study really be compared to "normal" methods of weight loss?
- The contestants had such huge amount of weight loss over a short period of time. Amounts even bypass surgery has a hard time replicating.
- In addition, they did it undergoing a comparatively large amount of vigorous exercise compared to" normal" methods.
- Could the exercise, such a large amount actually have set them up for problems down the road?
- We have found a phenomenon of "muscular efficiency" - in that after about a 10% weight loss people's muscles can become more efficient. Efficiency being a bad thing for an obese person... in that they can do the same amount of work, but after weight loss with with less energy. For example, these numbers are not real, just for example purposes: at baseline maybe you used 5 calories to go up a couple flights of stairs, but after a 10% or more weight loss your muscle can actually go up the same amount of stairs but only burn 2 Cals!
- Not to mention our body is very good at figuring out how to conserve. In the same manner our body can decrease it's own production of steroids when we give people oral steroids, could our body down regulate our metabolism if it knows we are going to be forcing it use up a bunch of energy by working out vigorously for 90 minutes pretty much daily???
All food for thought 😉
Rosenbaum M et al. Am J Physiol Regul Integr Physiol 20