Tuesday, March 19, 2013

Predictive Value of Equations to Calculate Your Resting Metabolic Rate (RMR) Flawed: Results Can Be 14-29% Off

Would she still look so happy, if she knew that thee treadmill just lied to her?
I have written, said and, in person, even shouted it out often enough: Once you start to rely on the figures certain formulas generate (and this includes what your treadmill, your heart rate monitor etc. will produce, 'cause they use the same flawed formulas), you are lost.

The message of today's SuppVersity article is therefore by no means a new one. What's pretty new, though, is the study by V. Bonghana and colleagues from University of Campinas who have compared five predictive equations that are supposed to predict your and everyone else's basal (=excluding physical activity) energy demands (Bonghana. 2013).

"Start with a 15% energy deficit" - based on what?

The above, i.e. to start dieting by consuming ~15% less energy than you usually do, is my usual suggestion for anyone who's not in the "so fat that your health is in danger" zone, someone like you, maybe - someone who wants get rid of his/ her belly to finally see a at least the uppermost portion of his / her abs.
Table 1: The five equations the researchers used to calculate the predicted resting metabolic rate (RMR) that was then compared to the measured RMR (indirect calorimetry by respiratory gas analysis) of the 43 participants (Bonganha. 2013)
Now, what do you think would happen if this person was a postmenopausal women (of whom many, as we all know, love to "diet" exactly as they are told to, counting calories and what not) who is too lazy to follow my even more important advice to track her caloric intake for 2 weeks in order to get a "baseline reading"? What would happen if this woman, instead of doing just that simply used one of the calculators on the Internet and build her diet right according to the number the machine vomits out?
Figure 1: Comparison of the predicted resting metabolic rates and the mean difference to the "real" (=measured) RMR of the 43 healthy postmenopausal women who participated in the study (Bonghana. 2013)
Actually a cursory look at the data in figure 1 should suffice to tell you what the result would be. If she was lucky and the calculator used the rather uncommon Mifflin-St Jeor equation she would not lose a single pound, because she would end up right at the 1,063 kcal/day she, a 52-year young women, who's 159cm small has a totally age-appropriate BMI of 25kg/m², but a slightly high body fat level of 33%, just like the "average subject" in our experiment, needs to fuel her most basic metabolic demands (measured those are 1063.8 kcal/day). The former obviously implies that she did also take into account that she spends a few extra calories, even when she does not exercise.

Use the WHO calculation and you are lost

Guess how she got in in shape? Right! The EDC Program (learn more)
If she was not just as lucky and used the WHO equation as a baseline, she would not only overestimate her basal energy requirements by more than 30%. No, even with the 15% reduction she would be continuously gaining gaining wait... now, imagine she had also started to work out and had for once heard received some good advice, which is not to freak out about the weight gain, because it's all muscle. What? Right, she would be working away instead of towards her goal to lose weight and fat, 'cause one thing is sure.

Unless you expend more energy than you eat it is almost impossible to get rid of the belly. Unfortunately, simplistic calories in vs. calories out calculations won't help you find out whether this is the case..

The notion that exercise "alone" can, especially for those who are pretty chubby to begin with, have a "repartitioning effect" may still hold here, but it is more  likely that our imaginary post-menopausal training rookie is - if anything - gaining more muscle than fat and that's certainly not going to give her the look she is aspiring. In fact the situation would probably not be much different from the one in the study I had in the Facebook News a couple of days ago (Tibana. 2013).

Adding exercise on top of a proven (your N=1 experience) obesogenic diet rarely helps

In the course of this 8-week intervention study, the subjects, a group of 14 middle-aged (33.9 ± 8.6 years) overweight/obese women (body mass index - BMI 29.6 ± 4.1 kg/m²) underwent 24 sessions (3 times per week) of a whole body RT program with 3 sets of 8–12 repetitions maximum (RM). Unfortunately, for them without any dietary advice / incentive to modify the baseline diets that were obviously to blame for the extra-weight they were carrying.

Figure 2: Body mass, waist, hip, neck circumference, body adiposity index and visceral fat volume in middle-aged women before and after an 8-week 3x/week full body weight training intervention (Tibana. 2013)
The net result of this "intervention" was thus by no means representative of what you can achieve, when you really commit. If you discard the diet component, or even worse, fall for the common idea that you've worked out for an hour and could thus "afford" that piece of pizza, pie or panacotta, you are effectively bulking. Therefore, you should thus not be surprised, if you got strong and bulky, but don't see improvements in your body fat level, your waist line and any of the biochemical variables, i.e. fasting glucose, HbAIc, insulin,  triglycerides, HDL, and the TG/HDL ratio (not shown in figure 2), your doctor will be eyeballing.

Without taking a "baseline reading" and accessing where you want to go, you ain't going to succeed (read more)
Bottom line: In conjunction, the results of the Bonghana and Tibana papers only underline the necessity to (a) make a baseline assessment of your current, individual food quantity and quality(!), before you embark on any kind of diet and (b) that the notion of "exercising the fat away" is only useful when you are not making the mistake to chart your dietary intake up against whatever you believe your exercise induced energy expenditure would look like. Even if it's not pizza, pasta and panacotta you are thinking of, when you look at the figure your treadmill or heart rate monitor calculated based on similarly whacky formulas as those used for the RMR, you are still lost whenever you put more faith into a impersonal arithmetics than the signals of your own body... and this, gentleman, is true irrespective of your age and sex.

If you still insist on calculating something, you may also want to take a look at Part III / III of the Female(?) Athlete Triad Series, but please be aware that I am not liable for the damage this type of calorie counting is going to do to your physique and your psyche.

  • Bonganha V, Libardi CA, Santos CF, de Souza GV, Conceição MS, Chacon-Mikahil MP, Madruga VA. Predictive equations overestimate the resting metabolic rate in postmenopausal women. J Nutr Health Aging. 2013;17(3):211-4.
  • Tibana RA, Navalta J, Bottaro M, Vieira D, Tajra V, Silva AD, de Farias DL, Pereira GB, de Souza JC, Balsamo S, Cavaglieri CR, Prestes J. Effects of eight weeks of resistance training on the risk factors of metabolic syndrome in overweight /obese women - "A Pilot Study". Diabetol Metab Syndr. 2013 Feb 28;5(1):11.