When it comes to nutritional supplements, it seems there’s nothing hotter than protein shakes. These whey or casein-based powders pulled in $396 million in 2012 alone. And, that number is only growing.
But while most protein consumers are looking for an edge in the weight room, an increasingly large portion of users are looking for something else. These folks just want to lose a little weight.
Can protein shakes actually help you pulverize those unwanted pounds? Protein is primarily used to support lean muscle growth, but studies reveal these properties may have strong weight loss implications.
What Protein Does for Weight Loss
Traditional weight loss supplements have a direct influence on fat burning. By cranking up the body’s core temperature, stimulants and other weight loss aids increase metabolism and support a caloric deficit. Protein takes a more indirect route to weight loss, but it is just as important.
In fact, board-certified clinical nutritionist Byron J. Richards goes so far as to call protein “the single most important calorie that influences your metabolic rate”.
A quality protein source helps you build muscle, improve fitness, boost immunity, and enhance insulin and leptin function. While these properties don’t directly affect weight loss, they all contribute to proper weight management.
Put simply, protein is a signaling molecule in metabolism. According to researcher Donald Layman of the University of Illinois, high protein intake ensures muscles are preserved during weight loss. This means the weight lost is mostly fat. It also increases metabolic rate, helping you create the caloric deficit needed to lose weight.
Protein may also have some effect on appetite control. According to Layman, the branched-chain amino acid leucine (found in protein) lowers triglyceride levels in the bloodstream. This helps leptin enter the brain, reducing leptin resistance and helping you feel full on fewer calories. This is especially true of whey protein, which provides high levels of leucine and other branched-chain amino acids.
Of course, when you’re eating less and your metabolic rate is increasing, weight loss follows.
Studies Support Protein’s Benefits
It’s one thing to theorize that protein supports weight loss; it’s quite another to prove it with supporting clinical studies. Fortunately, plenty of studies verify protein’s weight loss properties.
A 2005 study published in the American Journal of Clinical Nutrition examined protein’s effect on appetite, caloric intake, and changes in leptin and ghrelin concentrations. In this study, 19 subjects were placed on a weight maintaining diet for 12 weeks. Subjects consumed diets including varying amounts of protein. At the end of the study, blood was sampled and measured for insulin, leptin, and ghrelin.
Satiety was increased significantly in a high-protein diet, which supported a sustained decrease in caloric intake. Some subjects experienced weight loss as a result of these properties.
A 2004 clinical review conducted by Dr. Layman echoes these weight loss results. After analyzing 55 studies, Layman concluded whey protein with high leucine content in doses of 1.5 g/kg triggers weight loss. He identified leucine as the critical factor in improving metabolism and facilitating weight loss.
And it’s not just protein in general that supports weight loss. According to a 2008 study conducted at the Minnesota Applied Research Center, whey protein shakes also increase fat loss and lean muscle gains. In this study, researchers reduced subjects’ caloric intake by 500 calories per day. Some subjects then consumed a whey-protein drink called Prolibra 20 minutes before breakfast and dinner.
At the end of 12 weeks, body fat and lean muscle were measured. All subjects lost at least 2.25 kg of body weight, but those consuming Prolibra tended to lose more than the control group. The difference in body weight lost was not statistically significant, but the amount of body fat lost was. Specifically, the ration of fat to lean muscle loss was much larger in subjects drinking Prolibra.
These studies suggest Layman’s theories are correct. While protein doesn’t directly trigger weight loss, it provides several properties that make weight loss easier and healthier.
How to Use Protein to Lose Weight
Nutritionists agree protein shakes best help weight loss efforts when used as meal replacements. Though they shouldn’t be considered “the” solution for weight loss, meal replacement shakes take the place of one of your daily meals and help you decrease your daily caloric intake. Because protein is generally considered filling, you shouldn’t have problems replacing a meal with a protein shake.
Generally, protein shakes are about 150-200 calories.
However, if you take this route, you’ll need to make sure you’re getting proper nutrition elsewhere.
In fact, Mayo Clinic nutritionist Katherine Zeratsky recommends using protein shakes only from time to time, rather than relying on them every day.
If you’re going to use protein shakes as meal replacements, be sure you’re strict about your diet. The average adult requires just 48 to 56 grams of protein each day, and most people get this through their diet. If you’re consuming extra protein, you’re not doing anything to enhance weight loss efforts. In fact, you’re adding on unnecessary calories that may end up hurting your results.
Instead, use protein shakes strictly as meal replacements. If you’re still hungry, snack only on healthy foods like fruits, vegetables, and whole grains.
Protein shakes work best when used alongside other weight loss efforts, like healthier eating and regular physical activity.
-  The Economist Staff. 27 April 2013. “Protein Shakes: Bruising” Accessed 10 July 2013.
-  Richards, Byron J. 18 April 2013. “How Protein Helps Weight Loss” Accessed 10 July 2013.
-  Weigle, David S., Patricia A. Breen, Colleen C. Matthys, Holly S. Callahan, Kaatje E. Meeuws, Verna R. Burden, and Jonathan Q. Purnell. 2005. A high-protein diet induces sustained reductions in appetite, ad libitum caloric intake, and body weight despite compensatory changes in diurnal plasma leptin and ghrelin concentrations. The American Journal of Clinical Nutrition: Vol. 82, Issue 1.
-  Layman, Donald K. 2004. Protein Quantity and Quality and Levels above the RDA Improves Adult Weight Loss. The Journal of American College Nutrition, Vol. 23, Supplement 6.
-  Frestedt, Joy L., John L. Zenk, Michael A. Kuskowski, Loren S. Ward, and Eric D. Bastian. A whey-protein supplement increases fat loss and spares lean muscle in obese subjects: a randomized human clinical study.
-  3 Fat Chicks On a Diet! 4 October 2010. “Do Protein Shakes for Weight Loss Work?” Accessed 10 July 2013.
-  Zeratsky, Katherine. 17 April 2012. “Protein Shakes: Good for Weight Loss?” Accessed 10 July 2013.