Calorie Restriction vs. Exercise for Optimal Body Composition? Exercise Preserves Muscle Tissue and Prevents Metabolic Downregulation.

Those of you who listened to my comments on set points and reasonable weight loss on Super Human Radio, will already know that - other than Gary Taubes, for example - I am a huge advocate of exercise, when it comes to weight loss, -maintenance and overall improvements in body composition. Data from a recently published study (Soare. 2011), despite being evaluated from an anti-aging perspective, confirms the adequacy of approaching your body composition goals, by dietary modifications and exercise induced increases in energy expenditure, instead of just "eating less calories".

In their study, Soare et al compared 24 subjects who had been on a calorically restricted diet (CR, 1769±348 kcal/d) for an average of 6 years to 24 age- and sex-matched sedentary individuals (control, WD, 2302±668 kcal/d) and 24 body fat-matched exercise-trained (EX, 2798±760 kcal/d) volunteers, who were eating Western diets.

Figure 1: Total body weight, lean mass & fat mass in sendentary control, calorie restricted (CR) and exercise (EX) group. (Data adapted from Soare. 2011)

Although the researchers found that both, "the CR and EX groups were significantly leaner than the control (WD) group" both the greater amount of lean body mass (cf. figure 1) as well as their finding that...

Mean 24-hour, day-time and night-time core body temperatures were all significantly lower in the CR group than in the WD and EX groups (P≤0.01).

...underline the futility of every effort to achieve improved body composition, i.e, to maximize muscle (lean mass), while shedding as much body fat, as possible via (even moderate) caloric restriction.

Two other things are noteworthy, as well. Firstly, the reduction in body temperature, which is indicative of a downregulation of the metabolic rate, may be favorable for a longer, but that does not equate into more livable life. And secondly, the "Taubes-Hypothesis" that exercise is "useless", because "it makes you hungry" (the subjects in the EX group in fact consumed more calories) and you would compensate by eating more, anyway, would be relevant, only, if in fact "a calorie was a calorie" and "only calories" counted; the superior body composition of the exercise group, on the other hand, speaks for itself and does suggest that even Garry himself may benefit from one or another training session in the gym ;-)

Edit: As I hear in an anonymous comment Taubes is supposed to do resistance training. When he was talking to doctor Oz, he did however propose the hypothesis I refer to above and this really bothered me.

Exhaustive Aerobic Exercise Increases Serum Calcium Levels and Dietary Requirements

You probably have heard of the fundamental importance of calcium as a structural component of bones. Yet, calcium is way more than the building block of our bone structure and the concrete the of the hopefully non-existent plaque in your arteries. It is also one of the major players in muscle contraction. Thus, it is not very surprising that a group of Iranian Scientists (Pourvaghar. 2011) found major effects of pro-longed (15min) high intensity aerobic exercise on serum calcium levels of 12 randomly selected student athletes (22.36y; 75kg @ 1.76m):

[…] the participants' mean of serum calcium concentration in the first stage and before Balke exhausting aerobic exercise was measured 98.38 ng/mic L. In the second stage, i.e. after the exhausting aerobic activity, it increased to 114.96 ng/mic L. Research results indicated that the difference in serum calcium concentration between the first and second stages is significant (P= 0.0001).

With the calcium that is appearing in the blood of the athletes being leeched from bones, organs to fulfill the increased calcium needs of active muscle tissue. Due to calcium “consumption” and urinary losses, the scientists speculate, the overall result to be a negative calcium balance.

Figure 1: Serum Calcium levels of athletes before, immediately after and 24h after exhaustive aerobic exercise. (Pourvaghar. 2011)

In view of the fact that, in the 24h after exercise, there is no sudden falloff (only -9.13%) of blood calcium, I would yet advice against extensive calcium supplementation. Previous works from other researchers have conclusively shown that a nutritionally dense, calorically adequate, diverse, calcium-rich diet satisfies the needs of both, the average gymrat and the hard training endurance athletes.

For athletes on a weight-reduction diet, or active gym-goers who – due to whatever other reasons – consume a diet that is low (<1.000mg/d) in calcium supplementing with a bio-available form of calcium, like calcium citrate, could yet be a viable strategy to prevent bone loss and sustain exercise performance.