Considering CREX
Published 5.12.2016I haven't written about CREX is quite a while, not that I ever truly followed a "CREX" program, but as I have always used exercise in my attempt to CREX stands for calorie restriction with exercise, as opposed to CR for calorie restriction or CRON for calorie restriction optimal nutrition. People who follow CREX cut down on calories, but also use exercise to create the calorie deficit. CRON followers simply eat very little.
This LA Times story is about calorie restriction, not CREX but CREX is what it made me think of. The article is reporting on this study. The second thing Times story made me think of was how I would cut 500 calories from my diet. And then it got me to thinking that perhaps, having sliced about 300 calories from my diet (that number includes the effect of exercise and NEAT though) eight years ago (yes, it's been that long, maintenance IS possible) I'd only need to cut out another 200. Which then made me think about the NIH calorie calculator— it could be that what these people did is adjust their intake to the limit that would support the smaller body size, and then allowed their bodies to settle at that weight.
So I went back to check on the numbers for myself (meaning what I would need to do to meet the criteria in the study). Per the National Institute of Health (NIH), I need to cut my caloric intake by 200 calories to get to a BMI of 22, but that's in addition to the 300 hundred calories I had to cut out of my intake to reach my current size. So in other words, if I'd cut 500 calories from my total in the first place, I'd be where they say. That's not really CR, that's just eating the right amount of food for the body size you want. People who are CRONies generally try to be at the lowest range of healthy BMI, based on my reading and recollection.
I will note that in my calculation of the calories I'd need to cut out to get to a BMI of 22, I included the expected energy expenditure for my current activity levels, which are higher than average. Although I don't walk at my treadmill desk while working currently, I do still stand or pedal rather than simply sitting.
I do know that 500 calories doesn't represent as much food as most people would think and way more movement than most people would think. Obviously body mass makes a bit of difference, but 500 calories is 5 miles of walking at a pace fast enough to increase the heart rate and likely cause perspiration.
Ignorance of calorie totals for food and exercise does not negate the energy balance (otherwise known as calories in vs calories out or CICO). The fact that you can work out for an hour and then negate the calorie deficit with your post workout treat doesn't change the fact that the energy balance holds— ALWAYS.
Exercise matters, but so does NEAT
This New York Times article reports on a study looking at the effect of adolescent exercise on later weight gain — in rats. In this rat study, rats that exercised while young and ate what they wanted were not obese and metabolically healthier than rats that avoided obesity with calorie restriction (designed to match the energy balance of the runners). The control group of rats were sedentary and ate at will and got fat. The big "news" is the improved health of the exercisers, and the fact that they ate what they wanted. The running rats did not overeat because they were exercising.The author of the piece is part of the "exercise is not useful for weight loss" movement. Readers here may recall that I am very much against this movement and think that telling people that exercise is useless is beyond stupid. The further qualifiers "for weight loss" doesn't remove the stupidity in my view— at least in part because it's demonstrably untrue. Just because something is difficult doesn't make it impossible.
Exercise can certainly be part of a plan to lose weight— and some people can and do lose weight be simply increasing their daily movement. However, those that successfully lose weight with movement alone, I'm willing to bet, don't just increase their deliberate exercise, they also find ways to increase their NEAT (non-exercise activity thermogenesis).
Here is where I truly dissent from most experts and researchers on obesity. I do not accept that NEAT is simply a matter of genetics. As I've written previously, fidgeting might be genetic, but choosing to stand while working or watching TV is not. That is a conscious choice that anyone can make. Almost every job can be done standing.
This Science Friday interview with Kevin Hall is about the Big Loser study, but in answering one of the questions, Kevin Hall states that muscle tissue at rest doesn't really burn much energy. The average is 15 calories per day for every kilogram of muscle. So it's a fallacy to say that building muscle means that your metabolic rate won't fall.
What doesn't get discussed (because it never gets discussed) is NEAT. Hall also points out that adding about a kilogram of muscle is the limit unless you're a body builder, so it's just not the case that you can rely on building tons of muscle to increase expenditure. These results matter for bariatric surgery patients though, because they tend to lose muscle mass and that will slow metabolism by that 15 calories per kilogram. And building muscles is difficult— as any body builder will attest.
Disclaimer
Related writings:
- Fasting vs Calorie Restriction with Exercise
- The Stand Up Fitness Plan
- Walking the Weight Off While Working
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