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Metabolic Rate, Diet, and Exercise

May 29, 2005 11:39 AM

In reviewing some of my collection of articles and abstracts I found this one that is worth sharing.

Among other things it shows, some years ago when the research was done, that current recommendations for moderate exercise miss the mark by a lot. You have to do some more vigorous exercise.

The agnostic finding is that a very low calorie diet AND a large volume of aerobic exercise appears to lower the resting metabolic rate. Not a good thing. Dieting and jogging appear to reduce metabolic rate per unit of body mass, probably because total muscle mass is reduced as fibers are converted from FT to ST. These latter fibers are smaller and more efficient users of oxygen.

Later studies have shown that diet alone does not lower the resting metabolic rate per unit of muscle, but does lower the muscle mass and, therefore, the total basal metabolic rate. Not a good thing either.

None of these problems will present themselves on the Evolutionary Fitness program. And, what is more impressive is that as you increase your lean muscle mass and convert more of it to larger FT fibers, your basal metabolic rate rises by a substantial amount. FT fibers are expensive tissue, so you burn lots of energy at rest and you increase your ability to burn far more in activity. Plus, you won't be apt to fall and hurt yourself with the quick response and power you get from FT fiber.

The abstract follows.

1: Sports Med. 1991 Feb;11(2):78-101. Related Articles, Links

The impact of exercise and diet restriction on daily energy expenditure.

Poehlman ET, Melby CL, Goran MI.

College of Medicine, Department of Medicine, University of Vermont, Burlington.

In addition to the direct energy cost of physical activity, exercise may influence resting energy expenditure in 3 ways: (a) a prolonged increase in postexercise metabolic rate from an acute exercise challenge; (b) a chronic increase in resting metabolic rate associated with exercise training; and (c) a possible increase in energy expenditure during nonexercising time. It seems apparent that the greater the exercise perturbation, the greater the magnitude of the increase in postexercise metabolic rate. An exercise prescription for the general population that consists of exercise of low (less than 50% VO2max) or moderate intensity (50 to 75% VO2max) does not appear to produce a prolonged elevation of postexercise metabolic rate that would influence body-weight. Inconsistent results have been found with respect to the effects of exercise training and the trained state on resting metabolic rate. Whereas some investigators have found a higher resting metabolic rate in trained than untrained individuals and in individuals after an exercise training programme, other investigators have found no chronic exercise effect on resting metabolic rate. Differences in experimental design, genetic variation and alterations in energy balance may contribute to the discrepant findings among investigators. A relatively unexplored area concerns the influence of exercise training on energy expenditure during nonexercising time. It is presently unclear whether exercise training increases or decreases the energy expenditure associated with spontaneous or nonpurposeful physical activity which includes fidgeting, muscular activity, etc. The doubly labelled water technique represents a methodological advance in this area and permits the determination of total daily energy expenditure. Concomitant with the determination of the other components of daily energy expenditure (resting metabolic rate and thermic effect of a meal), it will now be possible to examine the adaptive changes in energy expenditure during nonexercising time. A plethora of studies have examined the combined effects of diet and exercise on body composition and resting metabolic rate. The hypothesis is that combining diet and exercise will accelerate fat loss, preserve fat-free weight and prevent or decelerate the decline in resting metabolic rate more effectively than with diet restriction alone. The optimal combination of diet and exercise, however, remains elusive. It appears that the combination of a large quantity of aerobic exercise with a very low calorie diet resulting in substantial loss of bodyweight may actually accelerate the decline in resting metabolic rate. These findings may cause us to re-examine the quantity of exercise and diet needed to achieve optimal fat loss and preservation of resting metabolic rate.

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Posted by: Flower Online [TypeKey Profile Page] at September 12, 2006 7:31 AM

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