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Dean Pomerleau

Diet, Exercise, or Both to Reduce Inflammation?

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Here is another study posted by Al Pater that particularly interested me, both because it focused on inflammation (now understood to be an important contributor to all of the major chronic diseases of aging) and because it focused on CR vs. exercise vs. both.

 

It compared the effects of one-year of a calorie restricted diet, aerobic exercise (without calorie restriction) or both exercise and calorie restriction on biomarkers of inflammation in overweight/obese postmenopausal women.

 

The results can be summarized as follows:

  • The diet-only group and the diet+exercise group lost close to the same amount of weight (8.5% vs 10.5%, respectively). The exercise-only group lost much less on average (2.5%), although there were some women in the exercise-only group who lost > 5% (see below).
  • "There were no significant differences between the diet and diet+exercise groups or between the exercise[-only] and control groups, in any inflammatory biomarker."
  • Virtually everyone* in the study who lost >5% of body weight saw a significant reduction in hr-CRP, an important marker of inflammation, independent of whether they lost weight via diet-alone, exercise-alone, or diet+exercise.

So by my reading, it looks like its either the weight/fat loss or possibly the energy deficit, rather than simply eating fewer calories, that determines the benefits, at least when it comes to biomarkers of inflammation in this population. In particular, the women who lost nearly 10% of their bodyweight saw a dramatic (and equivalent) improvement in biomarkers of inflammation whether they achieved this weight loss via a large calorie deficit, or via a more modest calorie deficit "topped off" with exercise.

 

--Dean

 

 

* Except for two outliers with very high hr-CRP who were excluded

------------------------

[1] Effects of a caloric restriction weight loss diet and exercise on inflammatory biomarkers in overweight/obese postmenopausal women: a randomized controlled trial.

Imayama I, Ulrich CM, Alfano CM, Wang C, Xiao L, Wener MH, Campbell KL, Duggan C, Foster-Schubert KE, Kong A, Mason CE, Wang CY, Blackburn GL, Bain CE, Thompson HJ, McTiernan A.
Cancer Res. 2012 May 1;72(9):2314-26. doi: 10.1158/0008-5472.CAN-11-3092.
PMID:22549948
Free PMC Article
http://cancerres.aacrjournals.org/content/72/9/2314.long
http://cancerres.aacrjournals.org/content/72/9/2314.full.pdf+html

Abtract

Obese and sedentary persons have increased risk for cancer; inflammation is a hypothesized mechanism. We examined the effects of a caloric restriction weight loss diet and exercise on inflammatory biomarkers in 439 women. Overweight and obese postmenopausal women were randomized to 1-year: caloric restriction diet (goal of 10% weight loss, N = 118), aerobic exercise (225 min/wk of moderate-to-vigorous activity, N = 117), combined diet + exercise (N = 117), or control (N = 87). Baseline and 1-year high-sensitivity C-reactive protein (hs-CRP), serum amyloid A (SAA), interleukin-6 (IL-6), leukocyte, and neutrophil levels were measured by investigators blind to group. Inflammatory biomarker changes were compared using generalized estimating equations. Models were adjusted for baseline body mass index (BMI), race/ethnicity, and age. Four hundred and thirty-eight (N = 1 in diet + exercise group was excluded) were analyzed. Relative to controls, hs-CRP decreased by geometric mean (95% confidence interval, P value): 0.92 mg/L (0.53-1.31, P < 0.001) in the diet and 0.87 mg/L (0.51-1.23, P < 0.0001) in the diet + exercise groups. IL-6 decreased by 0.34 pg/mL (0.13-0.55, P = 0.001) in the diet and 0.32 pg/mL (0.15-0.49, P < 0.001) in the diet + exercise groups. Neutrophil counts decreased by 0.31 × 10(9)/L (0.09-0.54, P = 0.006) in the diet and 0.30 × 10(9)/L (0.09-0.50, P = 0.005) in the diet + exercise groups. Diet and diet + exercise participants with 5% or more weight loss reduced inflammatory biomarkers (hs-CRP, SAA, and IL-6) compared with controls. The diet and diet + exercise groups reduced hs-CRP in all subgroups of baseline BMI, waist circumference, CRP level, and fasting glucose. Our findings indicate that a caloric restriction weight loss diet with or without exercise reduces biomarkers of inflammation in postmenopausal women, with potential clinical significance for cancer risk reduction.

Edited by Dean Pomerleau

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Thanks Dean.  A key issue in this is that *all* the subjects seem to have been overweight or obese.

 

So this paper does not give us any information about the possibly important question of whether the benefits vary by BMI, and whether the threshold beyond which exercise becomes problematic (couch potatoes were found to have cleaner arteries than marathoners in one study) is also related to BMI.

 

My recollection from long ago is that that threshold is much lower among those with lower BMIs.  Huge amounts of exercise is substantially beneficial for those with a BMI of 35, but progressively much less beneficial for those with BMIs below 25.  *Possibly* even net harmful above a rather low limit for those with a BMI of 20.

 

If yer start off with a hsCRP of 0.2 how much incremental benefit are yer going to see with exercise?

 

I am not really making a categorical statement here.  Rather posing a question I don't think they answered..

 

Rodney.

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Yes Rodney, I agree.

 

This study population (overweight/obese postmenopausal women) is obviously not representative of most CR practitioners, so the results may not generalize, especially since most of us have very low markers of inflammation already, probably as a result of weight loss / net energy deficit.

 

This is a problem with virtually all studies of diet and exercise - they focus on overweight/obese, or at best, "normal" weight individuals, and so may not be at all applicable to CR practitioners. That is one reason why I think it would be good if we could get some "citizen science" research going among the members of the CR Society.

 

 

--Dean

Edited by Dean Pomerleau

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Huge amounts of exercise is substantially beneficial for those with a BMI of 35, but progressively much less beneficial for those with BMIs below 25.  *Possibly* even net harmful above a rather low limit for those with a BMI of 20.

 

If yer start off with a hsCRP of 0.2 how much incremental benefit are yer going to see with exercise?

 

Well, my "one rat" evidence is that lots of aerobic exercise is not harmful to my hsCRP (= 0.36 mg/L), despite my 18.0 BMI at the time of my last bloodwork, but there certainly isn't much room for improvement.

 

--Dean

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Rodney said: "this paper does not give us any information about the possibly important question of whether the benefits vary by BMI,"

 

This is addressed in Table 6, which seemed to favor the overweight versus obese subjects.  BMI was also considered int that "adjusted for randomization strata [i.e., baseline BMI (<30, 30 kg/m2) and race/ethnicity (white, black, and others)] and age".

 

Note that in that table, older subjects received not significant benefit versus significant benefit for younger subjects.

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