|Image 1: Instinctively right? Milk contains soluble (=whey) proteins and casein. Are we overthinking things, when we rip them apart and does it even make a difference? Or is timing all that counts?|
QWill it make a difference, whether I use casein or whey protein on a diet and... what's the significance of having my daily allotment of protein spread evenly across the day vs. mostly (80%) in one sitting, when I am dieting?
In order to find the answer to this question a group of French scientists recruited 41 healthy, but chubby subjects (BMI ~32kg/m²; age ~33y) and put them on a relatively moderate caloric deficit that was calculated based on their basal energy requirement (what you would need lying around all day). In all four arms of the study, the macro-nutrient composition (25% as proteins, 25% as lipids, and 50% as carbohydrates) and energy content per pound of lean body weight (average energy intake 5.87 MJ per day) of the meals, which were prepared according to personalized menus the subjects received from trained dietitians, were identical.
*Note: the scientists refer to whey as "milk soluble protein, I stuck to the terminology in the graphs, but in essence these are mainly β-lactoglobulin, α-lactalbumin, as well as serum albumin, immunoglobulins, lactoferrin, and other minor fractions and thus the same you would find in your average whey concentrate which is, as you may have notices "more soluble" than casein (cf. Lacroix. 2006)
- casein spread- subjects consumed ~20g of a casein protein supplement 4x a day
- milk spread - subjects consumed ~20g of milk protein supplement 4x a day
- casein pulse - subjects consumed the lions share, i.e. 80% of their ~80g of casein, as part of their 2nd meal, so that the protein intake over the day was 6.4g / 64g / 3.2g / 6.4g (see figure 1)
- milk pulse - same as above, but with milk instead of casein protein
Differences are few and far between: Weight loss, fat loss, muscle loss - NOT different!
What may yet surprise even you, a seasons SuppVersity veteran, who will probably already have expected the non-significant (in fact non-existent) differences in terms of weight loss, could be surprised that the changes in body composition (see figure 1, bottom), i.e. -5.1 ± 0.2 kg reduction in body fat mass and -2.2 ± 0.2 kg reduction in lean body mass, were identical.
Since the same goes for the changes in the fat "liberating" proteins lipoprotein lipase (LPL) and adipose triacylglycerol lipase (AGTL), the fat "forming" protein fatty acid synthase (FAS), and three of the usual subjects, i.e. leptin, the adipoQ gene which is responsible for encoding adiponectin, of which recent research suggests it may be even more important than leptin for your metabolic health (Li. 2012; Hickman. 2012), and the reduction in the pro-inflammatory monocyte chemotactic protein-1 (MPC-1), the slightly more pronounced meal-induced postprandial protein synthetic response in the casein group at the end of the study period is actually the only difference based on which you could argue for one over the other protein source:
Adherence is the key to success: While there was no difference in terms of the hunger the subjects felt when they were on the diet, the fact that only 23 of the initially 41 subjects did make it through the 6- week on ~ 1,500kcal/day is quite telling, also in view of the perceived inability to lose weight - if you can't stick to a by no means crazy caloric restriction for 6 weeks, how can you expect to get lean and stay lean, when the inevitable prerequisite for the latter is that you totally revamp your dietary habits for the rest of your life not just six, eight, or twelve weeks.
- maybe something like "leucine resistance" in response to the higher leucine concentrations after the ingestion of the milk protein supplement in the course of the study period, or
- alternatively, the greater IGF-1 response to casein (cf. Hoppe. 2009, a study which compares whey vs. casein, but would obviously suggest an advantage of casein over milk = whey + casein, as well); unfortunately IGF-1 wasn't measured, but the insulin levels which were minimally higher in the casein group could support that hypothesis,
Maybe, just maybe, the adipocyte morphology could make a difference
What I would consider significant, though it did not reach that status (probably due to the low number of participant that actually made it to the end of the study, see red box on the right), is the slight but in my eyes potentially important superiority of the equally spread protein ingestion in terms with respect to the before vs. after adipocyte diameter in the casein group:
"[...] a differential expression of pro- and antiinflammatory factors with increasing adipocyte size resulting in a shift toward dominance of proinflammatory adipokines largely as a result of a dysregulation of hypertrophic, very large cells." (Skurk. 2006)and a recently conducted human trial, by Rizkalla et al. the main message this study should be sending out is not that it does not make a difference whether you use casein or milk protein as your main protein source on a diet, but that a high protein diet with a mediocre caloric reduction of ~20-25% and supplemented with high quality dairy protein (whey or casein) works: After all, more than -1kg of weight loss per week, 68% of the weight loss from fat in the absence of exercise is more than your average celebrity XYZ diet will do for you ;-)
Bottom Line: Against that background the study at hand supports previous findings of the importance of a threshold intake of protein. Interestingly, it did not confirm the notion that this threshold intake should be spread equally across the day, which is something most commenters (me included) read into the seminal paper by Loenneke et al., which found a statistically significant negative correlation not between total protein intake, but between the number of meals with 10g or more essential amino acids in them and abdominal obesity (Loenneke. 2012). So, does timing matter, or does it not?
- It does matter, when you work out, there is ample evidence to support that the ingestion of protein in the vicinity of the workout cannot just amplify the protein synthetic response but will also results in an increase in real world muscle gains.
- It appears that it does not matter, when you are dieting (only), though; not just the study at hand, but also the success many people report on intermittent fasting regimen, would support the notion that the more sustained anabolism you may be able to achieve by ingesting say 4x25g of protein instead of 1x80 + 2x10g has, compared to the total amount of protein you eat, relatively little influence on the conservation of lean body mass, when you are dieting.
- Adechian S, Balage M, Remond D, Migné C, Quignard-Boulange A, Marset-Baglieri A, Rousset S, Boirie Y, Gaudichon C, Dardevet D, Mosoni L. Protein feeding pattern, casein feeding or milk soluble protein feeding did not change the evolution of body composition during a short-term weight loss program. Am J Physiol Endocrinol Metab. 2012 Aug 14.
- Demling RH, DeSanti L. Effect of a hypocaloric diet, increased protein intake and resistance training on lean mass gains and fat mass loss in overweight police officers. Ann Nutr Metab. 2000;44(1):21-9.
- Hickman IJ, Whitehead JP. Structure, signalling and physiologic role of adiponectin - dietary and exercise-related variations. Curr Med Chem. 2012 Aug 9.
- Hoppe C, Mølgaard C, Dalum C, Vaag A, Michaelsen KF. Differential effects of casein versus whey on fasting plasma levels of insulin, IGF-1 and IGF-1/IGFBP-3: results from a randomized 7-day supplementation study in prepubertal boys. Eur J Clin Nutr. 2009 Sep;63(9):1076-83.
- Lacroix M, Bos C, Léonil J, Airinei G, Luengo C, Daré S, Benamouzig R, Fouillet H, Fauquant J, Tomé D, Gaudichon C. Compared with casein or total milk protein, digestion of milk soluble proteins is too rapid to sustain the anabolic postprandial amino acid requirement. Am J Clin Nutr. 2006 Nov;84(5):1070-9.
- Li FY, Lam KS, Xu A. Therapeutic perspectives for adiponectin: an update. Curr Med Chem. 2012 Aug 9.
- Loenneke JP, Wilson JM, Manninen AH, Wray ME, Barnes JT, Pujol TJ. Quality protein intake is inversely related with abdominal fat. Nutr Metab (Lond). 2012 Jan 27;9(1):5.
- Rizkalla SW, Prifti E, Cotillard A, Pelloux V, Rouault C, Allouche R, Laromiguière M, Kong L, Darakhshan F, Massiera F, Clement K. Differential effects of macronutrient content in 2 energy-restricted diets on cardiovascular risk factors and adipose tissue cell size in moderately obese individuals: a randomized controlled trial. Am J Clin Nutr. 2012 Jan;95(1):49-63.
- Skurk T, Alberti-Huber C, Herder C, Hauner H. Relationship between adipocyte size and adipokine expression and secretion. J Clin Endocrinol Metab. 2007 Mar;92(3):1023-33.
- Vatani DS, Golzar FA. Changes in Antioxidant Status and Cardiovascular Risk Factors of Overweight Young Men after Six Weeks Supplementation of Whey Protein Isolate and Resistance Training. Appetite. 2012 Aug 10.