Protein – it’s essential for building lean body mass and for overall health – but can it help you lose weight? Some experts think most people get more than enough protein in their diet but certain sub-groups of people may need more. Two such groups are athletes and people over the age of 65.
Why is protein so important for seniors? Higher protein diets help to preserve lean body mass and prevent sarcopenia, the loss of muscle tissue due to aging. Of course, it works best if you combine it with a resistance training program.
Should people who are trying to lose weight add more protein to their diet?
What does research show about protein and weight loss? In one study, researchers placed a group of overweight men and women on a weight loss diet with a 500 calorie per day deficit. The difference between the two groups was one group ate a high-protein diet while the other ate a diet lower in protein.
After a year, both groups lost an average of 10% of their body weight. There was no difference in weight loss between the two groups BUT there was a difference in how much body fat they lost. The high-protein group lost significantly more fat than the group that ate the lower protein diet. Since fat loss is the goal for most people trying to lose weight, a higher protein diet may be helpful if you’re trying to shed body fat.
Preservation of Lean Body Mass
Losing body fat while retaining lean muscle is challenging. When you cut back on calories to lose weight, you lose fat but you also lose muscle. The goal is to maximize the loss of body fat while minimizing the loss of muscle tissue. One way to do that is to consume more protein and resistance train regularly to build lean body mass.
How does protein help to preserve lean body mass when you’re trying to lose weight? For one, it blunts the release of cortisol. Cortisol is released during times of stress. Exercise and calorie restriction are two forms of stress that increase the amount of cortisol your adrenal glands release. Protein helps reduce cortisol release. Why is that a good thing? Cortisol has a catabolic effect on tissues. It breaks down the hard-earned muscle tissue you want to preserve.
In one study, overweight and obese older women who were trying to lose weight were placed on a calorie-restricted diet. (1400 calories) One group of participants supplemented with 50 grams of whey protein twice a day while the other supplemented with an equal amount of carbohydrates. The group that got the protein supplement experienced more weight loss than the group that got an equal amount of carbohydrates.
Not all studies show a higher protein diet (around 30% protein versus 15% protein) enhances total weight loss, although a number do. What research DOES show is diets higher in protein result in less loss of lean body mass when dieting. Higher protein diets may also lead to greater fat loss, based on some studies.
Protein and Weight Loss – What Are the Benefits?
There are a number of reasons protein is your ally when it comes to losing body fat. A number of studies show a diet high in protein is more satiating than one high in carbohydrates or fat. Research also suggests diets high in protein are more thermogenic, meaning they increase metabolic rate after a meal and generate more heat than a meal of carbohydrates or fat. In one study, only a high-protein diet was linked with an increase in thermogenesis over a 24 hour period. Increased satiety and greater thermogenesis? That’s a good combination when you’re trying to shed body fat.
Animal versus Plant-Based Protein
You might wonder whether the type of protein you include in your diet matters when you’re trying to lose body fat. Animal and dairy-based sources of protein like meat, eggs, and milk are complete protein sources. They contain all the essential amino acids your body needs but can’t make. In contrast, most plant-based sources of protein, with the exception of some, lack one or more essential amino acids. You can make up for this deficit by eating a variety of plant-based protein sources. Still, some research suggests protein sources that contain all the essential amino acids may be more effective for fat loss. At the same time, plant-based protein sources also contain more fiber and that helps with satiety, so there are advantages to each.
Are There Drawbacks to Consuming More Protein?
Some research has suggested that consuming a high protein diet over a long period of time may place stress on the kidneys and potentially increase the risk of kidney disease. Although studies are conflicting, a high protein diet appears to be safe for people who have healthy kidneys. On the other hand, people who already have kidney disease should limit the amount of protein in their diet. A high protein diet may increase the risk of kidney stones in susceptible people.
What about heart disease risk? Research shows diets higher in protein and lower in carbs have more favorable effects on lipids, especially triglycerides. There’s also some research showing soy protein has favorable effects on blood lipids.
The Bottom Line?
A diet higher in protein may have benefits when you’re trying to lose body fat. The key is to choose healthy, lean protein sources and balance it with fiber-rich vegetables since the fiber in veggies increases satiety and gives you the antioxidants you won’t get from many protein sources. If you’re adding more protein to your diet, keep things in a healthy balance by choosing more plant-based protein sources like quinoa, lentils, nuts, fermented soy and beans. These foods DO have fiber and antioxidants. Yes, protein can be your ally when you’re trying to lose weight but choose your protein sources wisely.
Examine.com. “How Does Protein Affect Weight Loss?” 1, 3, 11
Am J Clin Nutr May 2008 vol. 87 no. 5 1558S-1561S
Nutr Metab (Lond). 2012 Jun 12;9(1):55. doi: 10.1186/1743-7075-9-55.
J Gerontol A Biol Sci Med Sci. 2011 Nov;66(11):1218-25
Nutr Metab (Lond). 2012 Jan 27;9(1):5.
Asia Pac J Clin Nutr. 2008;17 Suppl 1:169-71.
International Journal of Obesity (2006) 30, S16-S23. doi:10.1038/sj.ijo.0803487.
“The Cortisol Connection”; Shawn Talbott; 2002
ephrol. Dial. Transplant. (2005) 20 (3): 657-658.
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