Saturday, March 15, 2014

Where Protein Fails, Protein + Resistance Training Succeed: Lifting Corrects Diet-Induced Decrease in Postprandial Protein Synthesis, But Fails to Normalize Net Retention

It takes pains to maintain your gains!
You will certainly remember the shocking revelation that simply eating more protein is not going to prevent the diet induced muscle loss that occurs whenever you consume less energy than you expend (read up on "Protein Intake & Muscle Catabolism: Fasting Gnaws on Your Muscle Tissue and Abundance Causes Wastefulness" | go for it!)...

Don't rejoice, the study at hand does not refute this - protein is still unable to counter the increase in atrogin-1 and other muscle cannibalizing proteins, but there is a "tweak" by the means of which you can at least avoid that its pro-anabolic affects are also impaired.
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What this "tweak" is? Well, that's easy: Heavy lifting. If you are familiar with the "muscle loss in zero gravity" research that has been conducted by and for the NASA in the past decades (e.g. Ferrando. 2002).this shouldn't surprise you. The NASA studies have after all shown quite conclusively that compared to bed-rest / chronic skeletal muscle unloading, starving yourself is almost "anabolic". No wonder that lifting heavy objects, and not dietary protein is the #1 when it comes to saving your muscular ass from shriveling away on a long and hard diet.

Why does resistance training work, if protein fails?

As discussed in "Protein Intake & Muscle Catabolism" (read it!), it's not a question of the pro-anabolic effects. You, as a suppversity reader know that the p-AKT/mTOR pathway that's activated by protein feeding is sufficient to increase the influx of protein into the musculature. What your beloved protein can't do, though, is to reset a different switch: The "sacrifice muscle to fuel more fundamental metabolic demands switch" which is triggered whenever you are in a long(er) term energy deficit.

"Training For Gains: High Intensity, Low Volume Strength Gains Stick." | more
So what can be done then? Well,... as it is so often the case, the answer lies - once more - open before our eyes: Hit the weights, down the protein and kick your diet's catabolic ass!

I know this sounds too easy, but if you take a peek at the weight loss diets of the average physique athlete and their appearance on stage, it stands out of question that the combination of resistance training and strategic protein supplementation spares muscle mass.

Now the verb "to spare", according to the Oxford English Dictionary, means "to leave (a person) unhurt" (OED.COM), which is - and you probably expected this already, not really accurate. Even the latest data from the School of Medical Sciences at the RMIT University in Melbourne and the Exercise Metabolism Research Group at the Department of Kinesiology of the McMaster University in Hamilton, Ontario, Canada, and the Canadian Sport Institute clearly demonstrates that you cannot switch the diet-induced protein wasting off, completely (Areta. 2014).
Figure 1: The large inter-individual differences make it virtually impossible to tell, whether the MURF-1 levels increased. The similarly catabolic (see overview in the middle) atrogin was yet significantly increased in the early (15g) and late phase (30g) after the workout during ED (Gumucio. 2013; Areta. 2014)
In the corresponding experiment, 16 young, healthy, resistance trained subjects (8 females, 8 males) who had been fed individualized pre-packaged meals delivering 45 kcal/kg FFM (macros: PRO / CHO / FAT 1.4-1.6, 3-3.5 and 0.5-1.5 g·kg BM) per day for five days before they went on a standardized energy 30% energy reduced diet containing approximately
  • 1.4-1.6g protein per kg total body mass, 
  • 4.0-4.5g carbohydrates per kg total body mass and
  • 1.5-2.5g fat per kg total body mass
for another five days. At the end of this "ED" period and five days on rations with only 30kcal/kg fat free mass, all subjects performed a standardized leg press workout (warmup + 6 sets of 8 repetitions at ~80% 1 RM with 3 min rest between set) that was followed by the ingestion of either 15g or 30g of whey protein or an isocaloric placebo.
Figure 2: SLC7A5 AA transporter expression (left) and myofibrillar fractional protein synthesis (% / hour; Areta. 2014)
What a brief glance at the data in Figure 2 does tell you, though, is that resistance training will effectively counter, the diet-induced downregulation of the pro-anabolic response to protein. What it won't do, though is to increase the net protein retention to levels comparable to those on an energy balanced diet!
A high protein intake doesn't normalize the levels of anabolic hormones, either | learn more
Loss ↑, synthesis down ↓ ➲ net protein loss - there is no way out! In conjunction with the concomitant reduction in protein synthesis (-27% in the study at hand), the combination of increased loss and decreased synthesis in a caloric deficit will always entail a net loss of protein (also in view of the endocrine deterioration | learn more). What exercise can do for you, though, is to counter the net-reduction in protein synthesis, i.e. maximize the amount of amino acids that is pumped into the muscle, before it's used for hepatic gluconeogenesis.
Contrary to what Areta et al. may have suspected the restoration of the protein synthetic response in the post-workout period did not restore the expression of the amino acid transporter gene SLC7A5 to normal. It is thus not surprising that...
Highly suggested read: " Evidence From the Metabolic Ward: 1.6-2.4g/kg Protein Turn Short Term Weight Loss Intervention into a Fat Loss Diet" | more
"[...] despite this elevation, exercise merely restored MPS [muscle protein synthesis] to a level that was similar to, but not exceeding, rates measured in EB [energy balance]. Accordingly, it appears the metabolic status of the muscle during short-term (5 days) ED [energy deficit] plus a ~10 h fast may dictate that contractile overload in isolation is not enough to increase MPS to values that otherwise would be observed when subjects are in EB." (Areta. 2014)
The results of this recent study do thus have to regarded as another nail an already boarded up coffin that's loaded with bro-scientific myths about "body recompositioning."
A word on "body recomposition": You cannot build muscle, while you are dieting. You can, however improve your body composition by losing more fat than muscle. In the mirror / on photos, the results will look like "gains" - in spite of the fact that you simply revealed the muscle that has always been hidden beneath the blubber.
Unlike the non-existent changes in amino acid transporter expression, the observation that 30g of protein are more effective than 15g will probably not come as a surprise to you - notwithstanding the fac t that this was "the first [study] to determine the acute muscle anabolic response to resistance exercise with two different doses of protein ingested after exercise during short-term ED", by the way. About as unsurprising as the researchers' (eventually unwarranted - I don't see a 20g protein group, here ;-) conclusion that their ...
"[...]results suggest that the optimal amount of protein to maximize the response to a single bout of resistance training while in ED may be above the level (20 g) found to maximize MPS post-exercise for individuals who are in EB." (Areta. 2014)
And my recommendation, not to worry too much about all the details. There are a couple of simple principles that have been working for generations of athletes thriving to cut weight without having to sacrifice muscle mass; and as you should know if you've read and memorized the "9 Simple Rules Every Dieter Must Follow" (go back) consuming 30g of protein with every meal and lifting heavy objects are both part of a set of rules that's rooted in bro- and supported by pro-science.
"There is Such a Thing As Over- training, Beware! When IGF-1 & Co Plummet and MAFbx Gnaws Away Your Muscles, It'll Be Too Late to Acknowledge" | more
Bottom line: In the end, the results of this study are probably less exciting than the title, i.e. "Reduced resting skeletal muscle protein synthesis is rescued by resistance exercise and protein ingestion following short-term energy deficit" may have suggested.

That's yet not the least owed to the fact that you all know what it takes to maximize lean mass retention. If there wasn't that irrational hope somewhere deep inside your head that there was a hitherto unknown non-pharmacological way to build muscle and lose body fat at the same time, you'd now be hitting the weights or enjoying your post-workout protein shake... ;-)
Reference: 
  • Areta, José L., et al. "Reduced resting skeletal muscle protein synthesis is rescued by resistance exercise and protein ingestion following short-term energy deficit." American journal of physiology. Endocrinology and metabolism (2014). Ahead of Print.
  • Ferrando, Arny A., Doug Paddon-Jones, and Robert R. Wolfe. "Alterations in protein metabolism during space flight and inactivity." Nutrition 18.10 (2002): 837-841.
  • Gumucio, Jonathan P., and Christopher L. Mendias. "Atrogin-1, MuRF-1, and sarcopenia." Endocrine 43.1 (2013): 12-21.