Eat Less for More Muscle?

Always looking for something for nothing, this might be the ultimate. When I was a competitive bodybuilder and weightlifter I was always force feeding myself to gain weight and compete in higher weight classes, and as fun as that sounds it gets old. In the last few years I had been vaguely following the results of various starvation diets (now referred to as “calorie restriction” diets) but had never gone further than reading the Wiki and a few news articles on them. I knew they were associated with increased longevity in many species of animals now up to and including primates, but not yet tested in humans. While I expect the calorie restriction diets have a number of health benefits I would have figured those animals to be both thinner and frailer, so I was surprised by this study, making it a most fascinating read (full text at the link):

Cellular adaptation contributes to calorie restriction-induced preservation of skeletal muscle in aged rhesus monkeys. McKiernan SH, Colman RJ, Aiken E, Evans TD, Beasley TM, Aiken JM, Weindruch R, Anderson RM. Exp Gerontol. 2012 Mar;47(3):229-36. [FREE FULL TEXT]

We have previously shown that a 30% reduced calorie intake diet delayed the onset of muscle mass loss in adult monkeys between ~16 and ~22 years of age and prevented multiple cellular phenotypes of aging. In the present study we show the impact of long term (~17 years) calorie restriction (CR) on muscle aging in very old monkeys (27-33 yrs) compared to age-matched Control monkeys fed ad libitum, and describe these data in the context of the whole longitudinal study. Muscle mass was preserved in very old calorie restricted (CR) monkeys compared to age-matched Controls. Immunohistochemical analysis revealed an age-associated increase in the proportion of Type I fibers in the VL from Control animals that was prevented with CR. The cross sectional area (CSA) of Type II fibers was reduced in old CR animals compared to earlier time points (16-22 years of age); however, the total loss in CSA was only 15% in CR animals compared to 36% in old Controls at ~27 years of age. Atrophy was not detected in Type I fibers from either group. Notably, Type I fiber CSA was ~1.6 fold greater in VL from CR animals compared to Control animals at ~27 years of age. The frequency of VL muscle fibers with defects in mitochondrial electron transport system enzymes (ETS(ab)), the absence of cytochrome c oxidase and hyper-reactive succinate dehydrogenase, were identical between Control and CR. We describe changes in ETS(ab) fiber CSA and determined that CR fibers respond differently to the challenge of mitochondrial deficiency. Fiber counts of intact rectus femoris muscles revealed that muscle fiber density was preserved in old CR animals. We suggest that muscle fibers from CR animals are better poised to endure and adapt to changes in muscle mass than those of Control animals.

My Comments

So I learned a rhesus monkey hits middle age when 16 years old and has an average life expectancy of 27 years with age related declines in function similar but 2.5-3 times faster than in humans. Calorie restriction (CR) monkeys reached their peak in leg muscle mass at 18 years, 2 years after the control monkeys, and they held onto their muscle longer. Body weight of CR monkeys was 20% lower than controls with body fat 35% lower. At 27 years of age upper leg muscle mass of the CR monkeys was 1347 grams compared to 1218 grams for controls (10.6% more in the CR monkeys). 27 year old CR monkeys maintained 73.03% of their peak muscle mass at age 18 compared to control monkeys maintaining only 56.80% of their peaks at age 16. CR monkeys had less fibrotic material in their muscle tissue 6.44% compared to controls with 13.98%. CR monkeys maintained more fast twitch (type II) muscle fibers (typically lost with age), had larger type II muscle fibers, and they had greater number and larger slow twitch (type I) muscle fibers compared to controls. CR monkeys still lost type II muscle fibers over time, but it was delayed ~10 years in comparison to controls. Basically the CR monkeys were better off, A LOT BETTER OFF, on every measure. It’s probably worth mentioning that the researchers noted the CR monkeys had a more youthful appearance and 5/15 of the control monkeys died, while only 2/15 CR monkeys did.

With a number of the physical therapy patients I treat being seen for balance and fall risk which is primarily due to sarcopenia (age related muscle loss) dietary restrictions that maintain muscle mass and health while positively affecting a number of other disease processes might be very beneficial. It’s always worth noting that these results are in monkeys and may not apply to humans, though generally they do. The amount of calorie restriction was 30%, which is less than a monkey wants to eat but not enough to make them malnourished. From what I have read a 30% reduction in calories (compared to what the average organism wants to eat) seems to be the sweet spot with regards to slowing the aging process and in this case maintaining muscle mass. I expect in a few decades they will have human research that collaborates this one on the monkeys, but in the meantime I think I’m skipping breakfast, and maybe lunch. And as much as I advocate for exercise, eating less is a lot easier, cheaper, certainly more convenient than working out more.

As always, if you have any further questions or need for clarifications, please don’t hesitate to ask. Being aware that some of my blog ideas are contentious and occasionally a bit out of the field of my expertise, I encourage my readers to come forth with any questions/comments that are of interest or concern. Your comments are valued and welcomed.

Chad Reilly is a licensed physical therapist, located in North Phoenix, practicing science based medicine with treatment protocols unique and effective enough to proudly serve patients from Phoenix, Scottsdale, Mesa, Chandler, Tempe, Peoria, and Glendale.

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