Fat Loss in Primates

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Hi folks:

We have often discussed the important question of what proportion of the amount of weight lost in the transition to CR is fat, and how much of the loss is from lean body mass.

There are a couple of particularly interesting numbers in this paper referenced by Randy:

Blanc S, Schoeller D, Kemnitz J, et al.

Energy expenditure of rhesus monkeys subjected to 11 years of dietary restriction.

J Clin Endocrinol Metab 2003;88:16–23.

First here is the abstract:

Energy expenditure of rhesus monkeys subjected to 11 years of dietary restriction.

Blanc S, Schoeller D, Kemnitz J, Weindruch R, Colman R, Newton W, Wink K, Baum S, Ramsey J.

Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53706-1571, USA.

Dietary restriction (DR) is currently the only paradigm that has consistently extended maximal life span and reduced the onset of age-related chronic diseases in all of the nonprimate species tested. Although it is controversial, some investigators have suggested that the underlying mechanisms may be mediated by adaptations in energy expenditure. We evaluated the extent to which DR alters energy metabolism in a unique cohort of rhesus monkeys submitted to DR for 11 yr. Total energy expenditure (doubly labeled water), resting energy expenditure (REE; indirect calorimetry), and nonbasal energy expenditure (calculated by difference) were measured in DR (n = 12) and control (n = 11) animals. Body composition was determined by dual energy x-ray absorptiometry. Both fat mass and fat-free mass were lower in the restricted animals (56% and 12%, respectively). DR induced a 17% lower total energy expenditure that was attributable to a 20% decrease in REE without changes in the nonbasal energy expenditure. Adjusted for fat-free mass, REE was 13% lower with DR (-250 kJ/d). Taken together with a reanalysis of previous DR experiments published in humans, rodents, and monkeys, these results suggest that DR may lower REE independent of the DR-induced changes in body composition. Whether this reduction in REE contributes to the life-extending properties of DR warrants further analysis, but it suggests that the long-standing debate regarding DR effects on metabolic rates may derive from the lack of consensus on how to adjust for body size and composition.

PMID: 12519821

The numbers I find of interest are these:

"Both fat mass and fat-free mass were lower in the restricted animals (56% and 12%, respectively)."

Taking the above numbers and applying them to a theoretical example of a human starting out at weight 175 pounds with 25% body fat, and seeing a 56% reduction in body fat and a 12% reduction in lean mass, the following numbers emerge:

Weight total fat lean

Starting: 175.00 43.75 131.25

Ending: 134.75 19.25 115.50

%change: -56% -12.5%

Lbs lost: 40.25 24.50 15.75

% lost 100% 60.9% 39.1%

The point of all this? Once again we see another empirical example where, in round numbers, 60% of the weight lost is fat, 40% of weight lost is lean body mass.

Rodney.

>> In regard to the current discussion of metabolic rate in rodents, > please note that primates and humans consistently show reduced EE as > opposed to mixed results in rodents. [1], [2], [3]> > For a discussion of these conflicting results see:> > Calorie restriction and aging: review of the literature and > implications for studies in humans1 [4]> > 1.Blanc S, Schoeller D, Kemnitz J, et al. Energy expenditure of > rhesus monkeys subjected to 11 years of dietary restriction. J Clin > Endocrinol Metab 2003;88:16–23.[Abstract/Free Full Text] > > 2.Ramsey JJ, Roecker EB, Weindruch R, Kemnitz JW. Energy expenditure > of adult male rhesus monkeys during the first 30 mo of dietary > restriction. Am J Physiol 1997;272:E901–7. > > 3. Girard N, Ferland G, Boulanger L, Gaudreau P. Long-term calorie > restriction protects rat pituitary growth hormone-releasing hormone > binding sites from age-related alterations. Neuroendocrinology > 1998;68:21–9.[Medline] > > 4. http://tinyurl.com/62gkc6>