Protein Supplements or Dietary Protein? What's the Better Muscle Protector in Exercising Older Individuals on a Diet?

Can drinking protein shakes outperform dietary protein when it comes to protecting aged muscle from diet induced catabolism? Find out...

Strategies to enhance weight loss with a high fat-to-lean ratio in overweight/obese older adults are important since lean loss could exacerbate sarcopenia, the loss of lean muscle mass with all its negative consequences on the ability to keep the weight off and manage ones everyday life.

In a recent study researchers from the McMaster University were able to show that both, resistance training and the provision of extra protein in form of either dietary proteins or a ready-to-drink whey protein micelle (WPM) beverage minimize the loss of lean mass in older men  (66 ± 4 y, 31 ± 5 kg/m²) on an energy restricted diet, but one works slightly better than the other.

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The subjects all of whom had to consume the same messed up lead-in diet that contained 55% of the energy in form of carbohydrates, 15% in form of protein and 30% in form of fat to mirror the average diet of the average elderly overweight individual. The main purpose of this the lead was to ensure participants commenced the study in EB and to minimize the influence of inter-participant differences in habitual protein intake.

During the subsequent 4-wk energy-restricted period, participants in both groups consumed a
diet providing 300 kcal/d less than their estimated energy requirements to maintain equal body weight.

"The diets provided 1.3 g protein/kg/d and dietary carbohydrate and fat were both manipulated within the ranges 50-55% and 20-25% of total energy intake, respectively, in order to achieve the target energy intake for each participant" (Murphy. 2015).

Although the diets in both groups contained the same total amount of daily protein, they differed in the distribution pattern:

• In BAL, protein was evenly distributed across the 4 daily meals (~25% of total protein intake at breakfast, lunch, dinner and pre-bed snack) with each meal providing ≥30g (≥0.33 g/kg) protein. 
• In SKEW the majority of daily protein intake was provided with the evening dinner meal (~7% at breakfast, ~17% at lunch, ~72% at dinner, ~4% pre-bed). In SKEW, the protein content of breakfast, lunch and the pre-bed snack was < 20g (< 0.22 g/kg) and dinner provided 70 – 110 g (~0.94 g/kg), depending on each participant’s daily protein requirement. 

In both groups, meals contained a variety of plant- and animal-based protein sources, but only in BAL a ready-to-drink whey protein micelle (WPM) beverage (240 g: 25 g protein, 3 g carbohydrate, 0.6 g fat; Nestle, Lausanne, Switzerland) was consumed as part of breakfast and the pre-bed snack as a practical means of achieving target protein intakes at these meals which are typically low in protein. The subjects from the SKEW group who did not consume any form of protein supplement got all their protein from dietary sources.

Figure 1: Graphical overview of the study design (Murphy. 2015).

To exclude placebo effects the subjects in the SKEW group did thus receive a protein-free, low energy placebo drink (240 g: 0.2 g protein, 3 g carbohydrate, 0.6 g fat; Nestle, Lausanne, Switzerland) that was similar in appearance, smell and taste to the WPM beverage, with breakfast and the pre-bed meal.

No, this is not an "advertisment study", I mean it's quite obvious that you could have used any whey protein supplement and would have seen similar results. Furthermore the product that was used may have been from Nestlé, the money for the study which had a pretty decent dietary control and used relatively objective DEXA scans to evaluate, however, came from Australian Research Council Linkage Project and the National Science and Engineering Research Council.

So to summarize, the only significant difference between the only difference between the two study groups you see in the illustration of the study design below is the use of a whey protein supplement as a major source of protein (vs. whole foods).

This does also mean that the resistance training sessions during weeks 3 and 4 participants were identical. More specifically, they consisted of three training sessions per week. Each session consisted of two upper body (chest press, seated row) and three lower body exercises (leg press, leg curl). Training sessions in week 3 consisted of 2 press, leg extension, leg curl; Hur, Finland). Training sessions in week 3 consisted of 2 sets, and in week 4 consisted of 3 sets (4 sets in the final training session) of each exercise performed to the point of volitional fatigue.

Figure 2: Figure 4. Myofibrillar (A, C) and sarcoplasmic (B, D) protein fractional synthetic rates (FSR; %/h) in the fasted (A-B; 0-2 h) and fed (C-D; 2-13h) state in the balanced (BAL) and skewed (SKEW) protein consumption groups in energy balance (EB, trial 1), after 2 wk of energy restriction (ER, trial 2) and after 2 wk of energy restriction and resistance training (ER + RT, trial 3). Note the difference in scales of the axes in panels A and B versus C and D. Values are means ± SEM, n = 20 (10/group). Dissimilar letters demonstrate within-group differences (p < 0.05). * Different from SKEW in the same trial (p < 0.05 | Murphy. 2015).

Against that background one could expect that the results were also very similar in both arms of the study, but the reality was - as so often - very different: Only in the BAL group, the exercise + protein induced increase in myofibtrillar fractional protein synthesis which occurred in both groups was sufficient to bring the FSR rates back to where they were in the non-dieting state (EB). In SKEW, however, the myofibrillar FSR remained lower than EB (p = 0.002) and lower than BAL (p = 0.006).

What neither of the dietary + exercise interventions could prevent, though, was a reduction of the sarcoplasmic protein FSR which happened to be reduced similarly in ER and ER+RT compared to the eucaloric state (EB | p < 0.01) in both groups. In view of the role of the sarcoplasm as the "home" of satellite cells and the impaired repair and recovery abilities of aged muscle, this shortcoming is probably more significant for elderly vs. young subjects. Against this background it's extra sad that we (a) don't have body comp data for the individual groups and that (b) the study was much to short to determine whether the advantage of whey would be really (=real world) significant in the long-term.

Where's the body comp data? Well, unfortunately, there is none. Well, at least no group-specifica data, because due to the small sample size the study was underpowered to detect stat. sign. differences in the changes in body composition. Overall, the loss of total body mass was - as it was expected higher during the initial (diet only) phase (pooled mean change: -1.4 ± 0.2 kg; main effect for phase p < 0.01). More importantly, body fat decreased over the intervention (p < 0.001) with no difference between phases and the lean mass loss of the diet only phase was fully attenuated in the RT + protein phase.

And still, despite the fact that the sarcoplasmic protein synthesis rates were decreased in both groups, the study at hand provides another convincing argument in favor of protein supplementation in the elderly. After all, Murphy et al. were able to show that the fast-digesting protein from whey supplements has a significant advantage over dietary protein when it comes to maintaining normal protein synthesis rates during a diet.

This and the fact that many old individuals are having a hard time (and are often unwilling) to eat two instead of one steak for dinner, drinking a protein shake for breakfast and another one for after dinner appears to be quite an easy solution to help maximize the muscle protective effects of resistance training during diets which are - in contrast to what you may hear some doctors say - as necessary in old obese individuals as they are in young(er) ones | Comment on Facebook!

References:

• Murphy, Caoileann H., et al. "Hypoenergetic diet-induced reductions in myofibrillar protein synthesis are restored with resistance training and balanced daily protein ingestion in older men." American Journal of Physiology-Endocrinology and Metabolism (2015): ajpendo-00550.