Download Fitness Tools

No, even the reanalysis doesn't say that a bit more protein, alone, will make you look like this ;-)

I've written about both observational and experimental studies that show how increased protein intakes can improve your body composition. So why mention another one?

Well, the study at hand which has been conducted by scientists from the Purdue University is interesting, because (a) it's not as extreme as Jose Antonios 2014 study in which the subjects consumed "Fivefold More Than the FDA Allows" (learn more), (b) it is not a simple short-term diet intervention where the high protein diet comes - as usual - out victorious and it is (c) actually a re-analysis of one of those studies that is often cited to "prove" that increased protein intakes, let alone the use of whey protein, wouldn't be advantageous for overweight and obese individuals trying to shed body fat.

But let's tackle one thing after the other. The original goal of the study at hand was to re-assess the data from Weinheimer's 2012 study which concluded that "whey protein supplementation [10, 20, 30, or 30 g of whey protein twice daily] does not affect exercise [2x resistance training 1x cardio per week] training-induced changes in body composition and indices of metabolic syndrome in middle-aged overweight and obese adults" (Weinheimer. 2012 | just to make sure you're not confused: While the lead authors changed Weinheimer <> Campbell, it's still the same team).
Instead of dealing with absolutes and overall averages, only, Campbell et al. reanalyzed their data to elucidate the influence of total protein intake (TPro) and changes in protein inatke (CTPro) on exercise-induced changes in body composition and metabolic syndrome indexes. As the scientists point out in the introduction to their soon-to-be-published paper, they conducted this assessment from 3 perspectives for protein intake as follows (Campbell. 2015):

1. TPro as a continuous variable with the use of a multiple linear regression model;
2. CTPro during the intervention vs. each subject s usual protein intake (post-intervention value minus pre-intervention value) with the use of multiple linear regression; and
3. TPro as a categorical variable, <1.0, ≥1.0 to <1.2, and ≥1.2 g per kg bodyweight, using a stratified analysis approach.

In that, Campbell et al. (2015) already expected that they would be able to correct their original findings. More specifically, they hypothesized that they'd find that a higher total protein intake, expressed as a continuous or categorical variable, would enhance the training-induced reduction of fat mass (FM) and gain of lean mass (LM), but not influence responses of MetS indexes (these were waist circumference, glucose, TGs, HDL cholesterol, and blood pressure).

Table 1: Overview of the results of the multiple linear regression analysis the beta² are quantitative indicators of the link between total protein intake (TPro) and change in protein intake (CTPro) (Campbell. 2015).

In addition, the scientists were quite convinced that they'd be able to show that the changes in body composition had been the most pronounced in those subjects with the highest increase in total protein intake over the course of the 36 week study period. And guess what!? Campbell et al. were able to confirm both hypotheses in their ahead-of-print paper:

• In conjunction with exercise training, higher total protein intakes promoted positive changes in body composition. What the higher protein intakes did not do, however, was to promote further improvements in critical markers of metabolic syndrome in the 117 overweight and obese middle-aged adults who participated in the 2012 original 36-week intervention.
• In addition, the changes in body composition, Weinheimer et al. observed when they conducted the study three years ago were the most pronounced in those subjects who recorded the largest changes in total protein intake via diet or supplements.

Figure 1. Temporal changes in the most important markers of body composition according to total protein intake of the subjects during Weinheimer's 2012 36-week intervention study (Campbell. 2015).

That's all great and certainly supports the physique improving benefits of high protein diets. What's a bit disappointing, though, is that similar correlations between higher or increased total protein intakes were not observed for any of the markers of metabolic syndrome (waist circumference, glucose, TGs, HDL cholesterol, and blood pressure).
References:

• Antonio, Jose, et al. "The effects of consuming a high protein diet (4.4 g/kg/d) on body composition in resistance-trained individuals." Journal of the International Society of Sports Nutrition 11.1 (2014): 19.
• Campbell, et al. "Higher Total Protein Intake and Change in Total Protein Intake Affect Body Composition but Not Metabolic Syndrome Indexes in Middle-Aged Overweight and Obese Adults Who Performed Resistance and Aerobic Exercise for 36 Weeks." J. Nutr. jn213595 (2015): Ahead of print.
• Weinheimer, Eileen M., et al. "Whey protein supplementation does not affect exercise training-induced changes in body composition and indices of metabolic syndrome in middle-aged overweight and obese adults." The Journal of nutrition 142.8 (2012): 1532-1539.

Is it really bad to drink that whey shake before you eat the bananas, strawberries and blueberries, because whey makes you insulin resistant? Sounds "bogussy" and a closer look at the questionable methodological choices of the scientists who conducted the study don't make the results sign. more credible.

In the fitness community, whey protein is the #1 on the "must have supplement" list. Multi-vitamins? Creatine? Who cares, as long as you get your 30g of whey per day, you're good... really? One of you recently send me a study that would suggest that "good" is not exactly the right word to describe the effects of whey protein on at least one out of the set of well-established parameters of optimal metabolic health: Your muscles' insulin sensitivity.

In the paper that has been published in the reputable scientific journal "Diabetes", Gordon I. Smith and colleagues describe an experiment the results of which clearly suggest that whey doesed at 0.6g/kg fat free mass has a sign. insulin-desensitizing effect in twenty-two sedentary (<1.5 hour of exercise/w) and weight-stable (<2 kg change for at least 6 months), 50-65y old postmenopausal women who participated in this acute response study.
Acute response? Yes, there it is, the first in a line of problems that reduces the significance of the results. After all, testing the acute response to a certain health cannot tell you anything about the long-term effects on said parameter... especially if your subject group due to being sedentary and in an age where the parameter in question is deteriorating, anyway.

But let's not be the "it's not bros, so it's not valid for bros"-guys. Let's rather take a look at (a) the procedures and (b) the results and make up our minds later. And let's first take a look at a handful of important parameters of the study design: To determine the insulin sensitivity, the scientists used two hyperinsulinemic-euglycemic clamp sessions with the subjects being randomly assigned to do the procedure with vs. without whey protein first.

If you've got brawn and brain you cannot ignore that whey is much more than a potent muscle builder | learn more

"Before each clamp procedure, subjects were instructed to adhere to their usual diet and to refrain from vigorous physical activities for three days. Subjects were admitted to the Clinical Research Unit in the late afternoon, where they consumed a standard dinner between 1800 and 1900 h, and then fasted, except for water, until the next morning. At 0600 h, a catheter was inserted into an arm vein for the infusion of a stable isotope labeled glucose tracer; catheters for blood sampling were inserted into the radial artery of the opposite arm and in retrograde fashion into the femoral vein of one leg. At ~0645 h, a primed, constant infusion of [6,6- 2 H2]glucose (priming dose: 22 µmol·kg body wt-1, infusion rate: 0.22 µmol·kg body wt-1·min-1), purchased from Cambridge Isotope Laboratories Inc. (Andover, MA), was started and 4 h later the hyperinsulinemic-euglycemic clamp procedure was initiated with two 5-minute priming doses (first 200 mU·m-2 body surface area (BSA)·min-1 then 100 mU·m-2 BSA·min-1) of human insulin (Novolin R, Novo Nordisk, Princeton, NJ); for the remaining 230 min, insulin was infused at a rate of 50 mU·m-2 BSA·min-1. Euglycemia (at blood glucose concentration ~5.6 mM) was maintained by variable rate infusion of 20% dextrose (Baxter, Deerfield, IL) enriched to 2.5% with [6,6-2H2]glucose" ().

During the "whey trials", the subjects consumed 0.6 g of whey protein (unflavored Unjury®, ProSynthesis Laboratories, Inc, Reston, VA) per kg FFM dissolved in 360 ml water or the same volume of water alone. In addition, the researchers conducted a trial in which the subjects consumed the same amount of leucine.
To figure out if any effect they would observe was induced by whey, i.e. a complex protein, or just the most-applauded whey ingredient, i.e. leucine, the scientists ran a follow-up test (1-4 weeks later) in which the subjects consumed either 0.0684 g/kg FFM of pure leucine (that's equivalent to the amount of leucine in the whey protein)  dissolved in 360 ml Kool-Aid® (Kraft 94 Foods, Inc, Northfield, IL) or the same volume of the Kool-Aid® solution alone during the clamp procedure. I don't have to tell you that this was a mistake that makes the results of this follow-up useless for comparisons to the previous trial, in which the whey protein was mixed with water - Kool-Aid is after all all-carbohydrate - with 0.9g carbohydrates per ml of junk... ah, I mean per ml of the soft-drink.

Figure 1: Clearance of glucose during the hyperinsulemic clamp for the whole body and the legs (Smith. 2015). It is noteworthy that there control vs. active treatment signalling protein response (mTOR, p-AKT, ACC, etc. - not shown in figure) did not show differences that could explain the alleged negative effects of whey on glucose uptake (see Figure 2).

This does not mean that we couldn't use the data from the leucine trial, at all, though. But let's be honest, who cares about the non-significance of the effects of a non-gluconeogenic amino acid (meaning that leucine cannot be converted to glucose by the liver) if you cannot compare them to the significant decrease in insulin-mediated glucose disposal (38.8 vs 51.9 µmol glucose per µU insulin/ml / min; P<0.01) the scientists observed in the whey condition, because the test was messed due to the use of a different and by no means "neutral" control?

Figure 2: Don't worry, while the scientists cleverly call the glucose disappearance into the legs "leg glucose uptake" it's just the product of blood flow to the legs times whole body glucose disposal and suffers from the same methodological short-come as the whole body glucose disposal that assumes that whey was non-gluconeogenic (data from Smith. 2015)

Rather than as a basis to argue that whey is bad and leucine is good, you can use the Kool-Aid glitch and the fact that leucine cannot be converted to glucose in the liver to substantiate the following hypothesis: If the scientists had accounted for the gluconeogenic glucose load from whey when they tested their allegedly sugar-free (manufacturer claim) whey protein vs. water in the previous trial, they would probably have found no significant effect of whey protein on muscular glucose uptake, because the test wouldn't have been unfairly thwarted in favor of the water control which came without the additional glucose load from the whey-induced gluconeogenesis in the liver.

Figure 3: Both, acute and chronic realistic and thus relevant studies show beneficial effects of whey on glycemia (Petersen. 2009) and insulin sensitivity (Pal. 2010) - you decide which studies to trust ;-)

Plus, even if we assume that this hypothesis wasn't true (I am pretty convinced it is), the results of the study at hand would still be an inexplicable artifice that stands in stark contrast to the well-proven multi-facetted acute and chronic beneficial effects of whey protein on glucose- and weight-management in healthy, diabetic and pre-diabetic individuals (Layman. 2004; Frid. 2005; Peterson. 2009; Akhavan. 2010; Pal. 2010) - effects of which no one ever claimed that they were mediated by acute increases in muscular insulin sensitivity, by the way; and that despite the fact that the data from Pal (Figure 3, left) clearly indicates that these benefits occur in the real world.

References:

• Akhavan, Tina, et al. "Effect of premeal consumption of whey protein and its hydrolysate on food intake and postmeal glycemia and insulin responses in young adults." The American journal of clinical nutrition 91.4 (2010): 966-975.
• Frid, Anders H., et al. "Effect of whey on blood glucose and insulin responses to composite breakfast and lunch meals in type 2 diabetic subjects." The American journal of clinical nutrition 82.1 (2005): 69-75.
• Layman, Donald K., and Jamie I. Baum. "Dietary protein impact on glycemic control during weight loss." The Journal of nutrition 134.4 (2004): 968S-973S.
• Morifuji, Masashi, et al. "Dietary whey protein increases liver and skeletal muscle glycogen levels in exercise-trained rats." British journal of nutrition 93.04 (2005): 439-445.
• Pal, Sebely, Vanessa Ellis, and Satvinder Dhaliwal. "Effects of whey protein isolate on body composition, lipids, insulin and glucose in overweight and obese individuals." British journal of nutrition 104.05 (2010): 716-723.
• Petersen, Brent L., et al. "A whey protein supplement decreases post-prandial glycemia." Nutr J 8.47 (2009): 1475-2891.
• Smith, Gordon I., et al. "Protein ingestion induces muscle insulin resistance independent of leucine-mediated mTOR activation." Diabetes 64.5 (2015): 1555-1563.

Don't expect weight loss wonders from high(er) protein and dairy intakes, but especially when the energy intake is not controlled both can have benefits the study at hand could not detect.

What's better a calorie reduced diet with the suggested amount of protein or one with a slightly higher amount of protein and extra low-fat dairy in it, when it comes to shedding the exuberant body fat off the hips, abs and buttocks of 104 overweight / obese (or with a body fat content of 37%+ "overfat") premenopausal women?

That's probably not exactly the way the scientists from the Utah State University, the Pennsylvania State University, the University of Illinois and the FB Technical Center (Shlisky. 2015) would phrase their research question, but in the end, their 24-week three-phase randomized weight loss intervention comes tried to answer exactly this question.
To learn more about the impact of higher protein intakes (30% vs. 20% of total energy intakes) and the purported "magic" of diets that are high in low fat dairy (in particular yogurt), Julie D. Shlisky and her colleagues had their subjects go through a three-phase weight loss intervention with

• the JumpStart phase (weeks 0–2), being intended to kickstart the subjects' weight loss on a ~35% energy deficit, phase (2), 
• the Weightloss phase (weeks 3–12; total of 12 weeks), during which the subjects were supposed to adhere to a 1,500-1,700kcal diet which came close to a 25-30% energy deficit compared to their baseline energy intakes, and
• the Weightloss Maintenance phase, (weeks 13–24; total of 12 weeks), over the course of which the subjects had to stick to a dietitian designed "energy-balanced" diet which had still ~20% less energy than the subjects baseline diet (see Figure 4, right)

If you look at the tabular overview of what the subjects eat (I won't reprint 4 pages from the full text here) you can easily get confused and think that there were five different groups, eventually it does yet all come down to two groups, the intervention (INT) and comparison (COM) groups and their different diets during the previously explained phases of the study.

Figure 1: Macronutrient compositions of the prescribed diets in the intervention and comparison group (Shlisky. 2015).

In that, the most significant inter-group difference were (a) the macronutrient composition with 30% PRO, 25% FAT, 45% CHO in the intervention group (INT) and 16-17% PRO, 24-25% FAT, 59% CHO in the comparison group (COM).

Figure 2: Total intake (g) of carbohydrates, proteins and fats during the 12 week weight loss and maintenance phases (Shlisky. 2015)

"[w]eekly educational sessions were held for both INT and COM groups throughout the 6- month study and included lessons on basic nutrition knowledge, exchange patterns of eating, portion size and control, purchasing and preparing food and modifying recipes as well as motivational lessons on outcome expectations, selfregulation and monitoring, problem- solving, lifestyle modification, emotion eating and motivation for walking" (Shlisky. 2015) 

In addition, the subjects were told to consume 5 servings per day (with a focus on low fat yogurt) in the intervention and 3 servings of dairy (excluding yogurt) in the comparison group, as well as to finally get their behind off the couch for a total of ~8,000-10,000 steps per day (that was ~30-40 minutes of walking per day).
Needless to say that the novelty of the physical activity, of which I'd like to remind you that it had the same volume for both groups, must be taken into consideration when we take a look at the results of the 24-wk study:

Figure 3: Relative changes in markers of body composition after the weight loss and weight maintenance phase; all values expressed as percent difference to the respective pre-values in both groups (Shilsky. 2015).

Now, if you look at the overall effects and inter-group differences in Figure 3, three things are remarkable: Firstly, all subjects lost a significant amount of body weight and body fat without having to starve themselves or spending hours on the elliptical or treadmill. Secondly, there were no inter-group differences, which means that neither the overall increase in protein intake (see Figure 2), nor the increased intake of low-fat dairy and most prominently yogurt (effectively, the difference was only 1 serving per day, because the INT subjects failed to hit their target of five and ate only four servings per day) had beneficial effect on (a) the actual weight and more importantly fat / lean mass loss and (b) the subjects' general ability to keep the weight off during the follow up.

Figure 4: Reduction in energy expenditure (% of baseline) and total step count (activity level) of the subjects in the weight loss and weight maintenance phases of the study (Shlisky. 2015)

If we also take into account the data from Figure 3 which depicts the reduction in energy intake from baseline and the total number of steps participants in both groups took on a daily basis, we could yet conclude that the lower dairy (no yogurt) + lower protein group achieved very similar results with less efforts. There is thus no debating the scientists conclusion that

"[h]ealthy premenopausal women with excess adiposity effectively lost BW and fat mass and improved some metabolic risk factors following an ERD with approximately 20% protein and 3 svg/d of nonfat dairy intake." (Shlisky. 2015)

The increased protein or dairy (in this case mostly yogurt) intake did after all not offer significant benefits, as neither of the existing differences in Figure 3 was statistically significant.
References:

• Bowen, Jane, Manny Noakes, and Peter M. Clifton. "A high dairy protein, high-calcium diet minimizes bone turnover in overweight adults during weight loss." The Journal of nutrition 134.3 (2004): 568-573.
• Bowen, J., M. Noakes, and P. M. Clifton. "Effect of calcium and dairy foods in high protein, energy-restricted diets on weight loss and metabolic parameters in overweight adults." International journal of obesity 29.8 (2005): 957-965.
• In particularly in conjunction with exercise, high(er) protein intakes have been proven have additive beneficial effects on body composition during weight loss (Layman. 2005)
• Josse, Andrea R., et al. "Increased consumption of dairy foods and protein during diet-and exercise-induced weight loss promotes fat mass loss and lean mass gain in overweight and obese premenopausal women." The Journal of nutrition 141.9 (2011): 1626-1634.
• Shlisky, Julie D., et al. "An energy‐reduced dietary pattern, including moderate protein and increased nonfat dairy intake combined with walking promotes beneficial body composition and metabolic changes in women with excess adiposity: a randomized comparative trial." Food Science & Nutrition (2015).
• Thorpe, Matthew P., et al. "A diet high in protein, dairy, and calcium attenuates bone loss over twelve months of weight loss and maintenance relative to a conventional high-carbohydrate diet in adults." The Journal of nutrition 138.6 (2008): 1096-1100.
• Zemel, Michael B., et al. "Calcium and dairy acceleration of weight and fat loss during energy restriction in obese adults." Obesity research 12.4 (2004): 582-590.