FROM T-MAG:
Demling et al (2000) compared two groups on a 2100 to 2300kcal diet containing 143gP (26%), 286gC (52%), and 49gF (20%). Both groups weight trained for twelve weeks but received 75g of their daily protein intake from either a whey-based drink or a milk-protein isolate drink (80% casein, 20% whey). At the end of the study, the milk-protein isolate group lost more fat (15.4lbs vs. 9.2lbs), gained more lean mass (9lbs vs. 4.4lbs), and gained more upper and lower body strength than the whey group. It appears that milk protein isolate ingestion, when on a training program, may be a better way to enhance fat loss and muscle gain.
Lands et al (1999) showed that when supplementing with 20g of whey or casein for three months, the whey group had up-regulated their antioxidant defense systems and had increased performance in an anaerobic exercise task. The casein group didn't improve on any of the above parameters. Therefore whey may be better for antioxidant protection.
Since the fast vs. slow debate focuses on whey (fast) vs. casein (slow), let's address that research here. In studies by Boirie et al (1997) and Dangin et al (2001), it was shown that whey protein is better for up-regulating protein synthesis while casein protein is better for down-regulating protein breakdown. Not much more has to be said about this since it's been discussed about a thousand other times on this site alone. The take-home message from these studies is that a milk protein blend or a supplement containing whey + casein may be your best bet for body composition improvements.
Next up, what about those kooky vegetarians? Well, in comparing an omnivorous diet (meat containing) with a vegetarian diet, Campbell et al (1995, 1999) demonstrated that strength gains and body composition improvements are impaired when meat is removed from the diet.
In their studies, subjects weight trained for twelve weeks while consuming a 2300kcal diet consisting of 70-90gP (12-15%), 267-317gC (49%), and 82-87gF (7-11%). The only difference between groups was the fact that one group ate a meat-free diet while the other group ate meat. At the end of the twelve weeks, the meat eaters lost 2.8lbs of fat while gaining 3.74lbs of lean tissue. The vegetarians, on the other hand, lost no fat weight and lost 1.76lbs of lean tissue. Bottom line, meat seems to be an essential part of the diet.
Regarding fish in the diet, Lavigne et al (2001) demonstrated that cod protein was better than soy or casein for increasing muscle glucose sensitivity and for preventing
insulin resistance in high-fat fed rats. Since codfish has a favorable omega-3 profile, the researchers duplicated their work using only the protein component of cod and the benefits remained the same. This indicates that eating fish may improve your carbohydrate sensitivity and ultimately your body composition and these effects may be independent of the fatty acid profile.
Finally, Lohrke et al (2001) showed that growing pigs fed a diet consisting of soy as the only source of protein had lower body weights, amino acid imbalances, increased cortisol levels, and increased muscle breakdown. The casein-fed pigs grew normally. This study indicates that a diet containing exclusively a low quality protein (soy in this case) may interfere with normal growth and development.
So, how do we use this information to our advantage? Well, since different protein sources confer different benefits, your best bet is to eat some fish protein (cod, salmon, tuna), some lean meat protein, and some milk protein isolates or whey/casein blends each day. Eating from a limited list of protein sources is a big mistake.
Depending on their individual needs, my clients typically eat a different protein source with every meal so that by the end of the day they've gotten complete protein from egg whites, fat free cheese, milk protein isolate shakes, cottage cheese, salmon or tuna and lean beef, not to mention the incomplete sources like mixed beans and mixed nuts.
Summary
• With all the media hype out there, the key to staying lean and mean is still diet, specifically, good food choices.
• A calorie is not a calorie because the macronutrient content of each meal affects the body's response to the feeding. That basically means you could change your body composition by eating the same amount of calories each day, but making different food choices. Meal timing also plays an important role.
• A high protein diet may be better than a moderate protein diet for fat loss.
• A protein is not a protein because different kinds of proteins affect the body in different ways. Milk protein isolate (80% casein, 20% whey) may be better than whey alone if your goal is fat loss. Whey looks like it's better for antioxidant protection, however.
• A supplement containing whey + casein may be your best bet for body composition improvements.
• Meat eaters can lose fat faster and gain more muscle than vegetarians, even if the vegetarians eat the same amount of calories and get the same amount of protein.
• Eating fish may improve your carbohydrate sensitivity and ultimately your body composition.
• Soy still sucks as a primary protein source.
About the Author
John M. Berardi is a scientist and PhD candidate in the area of Exercise and Nutritional Biochemistry at the University of Western Ontario, Canada. His company, Science Link: Translating Research into Results, specializes in providing integrated training, nutritional, and supplementation programs for high-level strength and
endurance athletes. For more information about our team or our services, please visit JohnBerardi.com
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Steve
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