Wednesday, July 18, 2012

"Exercise For Weight Loss" Part 2

English lays out what seems to be a fairly convincing case as to why we shouldn't count weight loss among the benefits of exercise.

However, I strongly disagree. I believe his arguments do not properly reflect the majority of research that has been conducted on exercise in the past 50 years.

It's True that Exercise Is Not a Silver Bullet.
 As a certified personal trainer, I absolutely adore exercise, but I'll be the first to admit that, by itself, it is not an incredibly effective solution for serious weight loss. Outside of The Biggest Loser, it's very difficult for an obese individual to shed pounds through exercise alone. It's far easier to eliminate excess calories from your diet (my favorite target is soda) than it is to burn them off by running on a treadmill, plain and simple.

The author does a nice job defending the status quo - more calories burned through exercise, combined with  eating fewer calories, by the laws of physics, that must cause weight/fat loss.  He even cites several studies which support his contention that exercise and diet together are effective to cause fat loss.  I don't completely disagree, but I don't think the science tells us the answer yet, as it is too immature.  

One explanation for why there are so many conflicting results from experimentation is that there are too many variables, and since there is no universal agreement about which ones are most important, researchers do not control for the same variables across the spectrum of their work.  If you think a calorie is a calorie, you may not control for carbohydrate content in your test subjects.  If you don't think insulin resistance is an important variable, you don't control for it.  What are the other variables that may or may not be considered important?  Type of exercise (short and intense, or long and slow?  Weights?  Swimming or non-water based?  In a hot climate or cold?).  Gender.  Age.  Inflammation.  History of obesity or lack thereof.  Somatotype - skinny and lean is not like round and puffy when it comes to weight loss issues.  Tendency to get muscle mass easily or less easily.  Vitamin D levels.  Quantity and quality of sleep.  Other micronutrient deficiencies.  Test subjects' use of drugs, prescription or otherwise.  Alcohol intake.  Type of work - sedentary of otherwise.  And that's probably not all.  

Given that each of these variables could have an impact on weight loss for any group of subjects being tested, it should not be surprising to find that the research is providing a mixed result.  And as any of you know who have seen two folks steeped in the research who decide to have a "I know science more than you do" - the case can be made citing any number of studies for either side of the exercise argument.

Tomorrow, I'll address what I believe is the most rational approach to this topic.

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