The Best Protein
by J. S. Volek, Ph.D., R.D.
Choosing the right proteins at the right times of the day can maximize your weight loss and help ensure you lose fat and build muscle. Common protein supplements include whey , casein (milk) , egg and soy . We are now learning protein quality is just as important as quantity in determining the effects on thermogenesis, protein synthesis, and protein degradation. Here is what we know.
Protein is the Most Thermogenic
Thermogenesis, or more appropriately the thermic effect of feeding, refers to the generation of heat due to digestion and metabolism of food. Several studies show protein to be more thermogenic than carbohydrates and fat. That means calorie for calorie more of the energy from protein is given off as heat and less is available for storage as fat.
In one study comparing high protein meals to high carbohydrate meals fed over a 9-hour period, it was found the thermic effect of protein was 10% of calories and only 6% for carbohydrate. That means if you ate a 500 calorie meal, the one rich in protein would result in 50 calories given off to heat, where the one rich in carbohydrates would result in only 20 calories given off to heat. Although few studies have specifically examined the effects of different protein supplements, whey protein would be predicted to have the greatest thermic effect because it stimulates protein synthesis, an expensive energy consuming process.
Best Protein for Thermogenesis
Not all protein is created equal when it comes to promoting a thermic effect. Danish researchers studied the effects of two high-protein diets rich in either soy or pork protein versus a high-carbohydrate diet on energy expenditure. The diets were fed for four days each. On day four detailed measurements of energy expenditure were made over a 24-hour period using a respiratory chamber. Compared to the high-carbohydrate diet, thesoy protein diet increased calorie burning by 58 calories a day and the animal protein (pork) diet by 118 calories a day. The results confirm the greater thermic effect of protein versus carbohydrates and further show that a higher quality protein source with all the essential amino acids promotes a greater thermic increase than a vegetable protein source like soy.
Pick the Right Protein at Night
As you sleep your body gradually enters deeper into a catabolic mode as the night progresses. This means your skeletal muscles begin to break down. This is not good for those concerned with building or maintaining muscle mass.
According to French researchers, you may be able to counteract this catabolic effect by consuming the right protein before bed. They gave healthy subjects 30 grams of either whey protein or casein protein and measured their protein balance for seven hours after this meal.
They discovered that whey protein resulted in a rapid increase in blood amino acids and protein synthesis, but it was short-lived. Casein on the other hand resulted in a prolonged increase in blood amino acids that resulted in a 34% reduction in protein breakdown. The net protein balance remained more positive for the casein protein over the 7-hour period. The authors attributed the superior long-lasting effect of casein to the slower absorption rate.
The implications are that casein would be a better protein choice to consume before bed to minimize muscle breakdown.Power-packed Protein for Workouts
Consideration of the digestion rate is important when selecting a protein for your workouts.
Whey protein is digested and absorbed more quickly than casein . Therefore, whey increases protein oxidation and protein synthesis more so than casein, whereas casein results in a slower release of amino acids that protect against protein breakdown.
Rapid digestion is key to getting amino acids to muscles quickly. A small amount of whey protein prior to a workout is perfect (6 to 15 grams should do the trick). For your post-exercise protein, taking whey again will work well if you plan to eat another meal soon after your workout. If you don’t plan to eat a regular meal for awhile, add some casein to help keep you in an anabolic state for an extended period.Practical Protein
My interpretation from this research in regards to choosing protein sources is:
- To take advantage of the thermic effect (fat burning) of food, choose protein over carbs. To stimulate even more thermogenesis, use a rapidly digesting, high quality protein source such as whey or egg .
- Combining proteins might be a good idea in the morning, such as adding whey to milk or using a blend of proteins. You may even addflaxseed oil , rich in omega-3 fatty acids, to slow the rate of digestion and help you feel full longer.
- Choose a fast absorbing protein source like whey or egg before and/or after your workout. Casein might be a better choice if you don’t plan to eat for several hours. Post-workout you may want to add some rapid releasing carbs to the protein to take advantage of the insulin effect, which helps shuttle protein into your muscles.
- Choose a slower digesting protein like casein before bed to prevent protein breakdown during the extended period while you sleep. Just consume the protein and leave out the carbs so that insulin is minimized and fat burning is emphasized over fat storage.