September 2016 Issue

Breakfast: Protein Power
By Andrea N. Giancoli, MPH, RD
Today's Dietitian
Vol. 18 No. 9 P. 14

Eating foods high in this macronutrient may help clients with weight management.

"Eat breakfast" and "Include protein at every meal" are two pieces of dietary advice upon which most dietitians can agree, particularly when it comes to counseling clients on weight management. Soon, dietitians may find themselves encouraging patients to make their first meal of the day a high-protein breakfast. Indeed, a growing body of research supports high-quality, high-protein breakfast consumption because it can give individuals a little extra boost to enhance weight loss and weight-control efforts.

Today's Dietitian speaks with experts and takes a look at the research to learn more about high-quality, high-protein breakfasts and their association with weight management.

High-Quality Protein Defined
Expert and researcher on the benefits of protein consumption, particularly at breakfast, Heather Leidy, PhD, an associate professor in the department of nutrition and exercise physiology at the University of Missouri, defines high-quality protein as coming from sources that "contain all—and are not limited in—essential amino acids." Protein quality also is evaluated using the protein digestibility-corrected amino acid score (PDCAAS) method, which assesses the amino acid profile and the ability of humans to digest the protein in a food source. A PDCAAS value of 1 is the highest and zero is the lowest.

Breakfast's Effects
In general, consuming breakfast has been associated with lower body weight and sustained weight loss maintenance.1 Eating breakfast vs skipping breakfast also has been shown to increase fullness while reducing appetite, food cravings, and neural signals that regulate reward-driven eating behavior.2 High-quality, high-protein breakfast consumption studies have yielded greater improvements in these responses, as well as decreases in late-night snacking of foods high in sugar and fat.2 What's more, there may be something special about breakfast, as there's some evidence that the feeling of fullness after a high-protein breakfast is greater compared with a high-protein lunch or dinner.2

Why Breakfast Is Best
It isn't entirely clear why the first meal of the day appears to be a key time for high-protein intake. Stuart Phillips, PhD, a professor in the department of kinesiology and director of the McMaster Centre for Nutrition, Exercise, and Health Research at McMaster University in Hamilton, Ontario, Canada, says breakfast is "the meal after your longest fast. We've gone without eating (most of us) for eight to 10 (perhaps more) hours, and this meal sets the stage, so to speak. Metabolically, it's like starting the day putting the right fuel in the system, and it kick-starts the repair and recovery processes."

Leidy speculates that it's possible that breakfast's effects are "related to the activation of the satiety system which, once activated, seems to stay elevated throughout the day. It could have something to do with activation of the metabolic processes or circadian rhythms in the morning that leads to a more healthful response."

The Protein Effect
What does protein do exactly? According to Leidy's research, data suggest that eating protein prevents the secretion of the hunger hormone ghrelin and stimulates the secretion of the satiety hormones PYY (peptide YY), GLP-1 (glucagonlike peptide 1), and CCK (cholecystokinin).3 In addition, protein appears to blunt the brain's responses to food stimuli and thus decreases food motivation and food cravings.3 According to Phillips, protein is more satiating than carbohydrate or fat, and therefore helps people feel full longer. Protein triggers the body to rebuild and repair damaged tissues such as muscle, bone, and skin. Through its satiating effects, protein can help curb cravings and enable people to lose more fat and less muscle during weight loss.2 Leidy's research found that satiety is greater when energy is restricted.3

When Leidy examined protein's effects on body composition, she found that a high-protein breakfast prevented gains in fat mass compared with skipping breakfast, whereas eating a normal protein breakfast (approximately 13 g) didn't.4,5 In addition, evidence shows that consuming a high-protein breakfast improves glycemic control throughout the day compared with eating a normal protein breakfast or skipping breakfast.5

How Much Is Enough?
Leidy and Phillips agree that the protein threshold for breakfast is about 30 g to help control appetite, increase satiety, and manage weight (see Table below). According to Leidy, adequate leucine intake also may play a meaningful role in this equation. "We have some data [under review] that also illustrates improved satiety with increased leucine. It has been proposed that about 2.5 g leucine is needed. In high-quality animal proteins, there's about 2.5 g leucine in 24 to 30 g protein."



Animal vs Plant Protein
When compared with plant-based proteins, animal sources of protein such as beef, pork, poultry, and fish usually are more protein dense, making it easier to reach a higher quantity of protein per meal, Leidy says. Most plant proteins lack one or more essential amino acids, with the exception of soy and quinoa. However, plant proteins can be complementary in the right combinations and yield complete proteins. This raises the question, "Are animal sources superior to plant sources, or vice versa?" If dietitians consider the PDCAAS, soy, milk, and eggs are valued at 1, while beef is lower with a score of 0.92.6 When it comes to other parameters such as stimulating protein synthesis, Leidy says, "There's fairly consistent data illustrating greater protein synthesis with whey vs soy. [However], from a satiety and weight management perspective, we really don't know." With respect to protein synthesis in the body, there's research that supports similar protein synthesis and skeletal muscle increases from soy protein consumption and whey protein consumption.7,8

But when choosing protein food sources, there's more to consider than protein alone. Melissa Joy Dobbins, MS, RDN, CDE, spokesperson, podcaster, blogger, media trainer, and president of Sound Bites, Inc, in Chicago, notes that "Plant sources of protein tend to provide more calories than animal sources for the same amount of protein. That may be something to discuss with patients or clients so they are aware, especially if weight control is a goal." On the other hand, from an overall health perspective, plant-based diets are associated with better health outcomes and lower risk of chronic disease. Furthermore, animal proteins lack crucial fiber and can be high in saturated fat and cholesterol, two nutrients of which clients should consume less.

Solid vs Liquid Protein
When comparing solid vs liquid sources of protein, Phillips says, liquid protein sources usually are digested faster than solid, so it's best to consume solid protein for greater satiety. "There's data illustrating greater satiety, reductions in food intake, and weight loss when protein is consumed as a solid meal vs a beverage," Leidy says, although she recognizes there's a need for protein in liquid form for individuals who participate in long workouts, the elderly, and cancer patients who experience increased satiety and reduced hunger.

Timing of Breakfast
One question that still remains: How soon after waking up in the morning should one consume a high-protein breakfast? It turns out this isn't an easy question to answer. When it comes to weight management and satiety, the evidence is lacking to pinpoint the breakfast timing sweet spot. But Leidy says to stay tuned as more research is conducted in this area.

— Andrea N. Giancoli, MPH, RD, is a nutrition communications consultant in Hermosa Beach, California.


References

1. Wyatt HR, Grunwald GK, Mosca CL, Klem ML, Wing RR, Hill JO. Long-term weight loss and breakfast in subjects in the National Weight Control Registry. Obes Res. 2002;10(2):78-82.

2. Phillips SM, Chevalier S, Leidy HJ. Protein "requirements" beyond the RDA: implications for optimizing health. Appl Physiol Nutr Metab. 2016;41(5):565-572.

3. Bolster D, Rahn M, Kamil A, et al. The effects of reduced protein-nutrition bars with enhanced leucine content on ratings of fullness in healthy women. Paper presented at: American Society for Nutrition Scientific Sessions & Annual Meeting at Experimental Biology 2016; April 5, 2016; San Diego, California.

4. Leidy HJ, Ortinau LC, Douglas SM, Hoertel HA. Beneficial effects of a higher-protein breakfast on the appetitive, hormonal, and neural signals controlling energy intake regulation in overweight/obese, "breakfast-skipping," late-adolescent girls. Am J Clin Nutr. 2013;97(4):677-688.

5. Bauer LB, Reynolds LJ, Douglas SM, et al. A pilot study examining the effects of consuming a high-protein vs normal-protein breakfast on free-living glycemic control in overweight/obese 'breakfast skipping' adolescents. Int J Obes (Lond). 2015;39(9):1421-1424.

6. Hoffman JR, Falvo MJ. Protein — which is best? J Sports Sci Med. 2004;3(3):118-130.

7. Anthony TG, McDaniel BJ, Knoll P, Bunpo P, Paul GL, McNurlan MA. Feeding meals containing soy or whey protein after exercise stimulates protein synthesis and translation initiation in the skeletal muscle of male rats. J Nutr. 2007;137(2):357-362.

8. Denysschen CA, Burton HW, Horvath PJ, Leddy JJ, Browne RW. Resistance training with soy vs whey protein supplements in hyperlipidemic males. J Int Soc Sports Nutr. 2009;6:8.

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