By Michael Ormsbee, PhD, Florida State University
Edited by Kate Findley and proofread by Angela Shoemaker, Wondrium Daily
To burn more fat, you don’t necessarily have to deprive yourself of food. Dr. Ormsbee explains how including more protein in your diet can help you expend more calories while feeling full after meals, so you can have your (protein) cake and eat it, too!
Protein and Metabolism
Not only is protein great for building or maintaining muscle mass, but it also benefits your metabolism and energy balance. There are three major components of total daily energy expenditure—resting metabolic rate, the thermic effect of activity, and the thermic effect of food.
The largest percent of total daily energy expenditure belongs to our resting metabolic rate (calories burned at rest), close to 75 percent. Metabolism tends to slow down as you age.
The overall decrease in metabolism is only about one to three percent during the entire aging process. As you age, though, you lose about five percent of your muscle mass every 10 years, so from age 40 to age 80, you could lose as much as 20 percent of your muscle mass, which would lower your overall calorie burn and metabolism.
However, we can take steps to prevent this decrease in metabolism. For example, if your resting metabolism is 1,800 calories per day, then the metabolic decrease over time could be somewhere around 20 to 60 calories in total. You can offset this with a few simple nutrition or exercise strategies, one of which might be eating more protein.
“If you are used to eating minimal protein, as many adults do, then even doubling your intake from what is currently recommended is likely a great thing to try,” Dr. Ormsbee said. “So you would simply be sure to have a good protein source at each meal to base the rest of your meal around.”
Coefficient of Digestibility
How does eating more protein help us adjust to a slowing metabolism? First, the macronutrients we eat—protein, carbohydrates, and fat—all have what is called a coefficient of digestibility.
This means that if you ate a food that was 100 percent carbohydrate, you would digest about 97 percent of that food. However, if it was all fat, you would digest about 95 percent of that food. If you ate 100 percent protein, you would only digest about 92 percent of that food.
Your body digests a certain percentage of those three macronutrients, and protein is the least digested, compared to carbohydrate and fat. That’s because your body cannot oxidize or burn the nitrogen in protein sources of food.
In essence, your body works hard to digest and absorb protein, and this is probably why eating protein gives you the largest increase in metabolism when eating it. This is called the thermic effect of food.
A number of research studies have been designed to measure metabolism after a meal containing protein versus fat versus carbohydrate, and the majority of these indicate that the greatest increase in metabolism comes after eating protein. Thus, by eating protein, you begin to increase your metabolism and your caloric burn.
Protein and Satiety
Outside of the increase in metabolism we get from eating protein, it also makes us feel full or satiated after eating it. Here, the research is also clear: Low-protein intake is linked to increased feelings of hunger and desire to eat again, while increased protein intake is linked to decreased feelings of hunger and less desire to eat again. Even without exercise, research is showing that adding protein to the diet of overweight but otherwise healthy people can improve body composition.
For example, in overweight and obese adults, nutrition scientists demonstrated that a protein supplement providing 56 grams per day of whey protein with no other dietary alterations resulted in significantly lower body fat mass by five pounds over 23 weeks. This was compared to a carbohydrate supplement of equal calories given to another test group.
Therefore, eating more protein may be the best nutritional strategy to manage body composition, given its influence on metabolism, satiety, and maintenance of muscle mass.
This article was edited by Kate Findley, Writer for Wondrium Daily, and proofread by Angela Shoemaker, Proofreader and Copy Editor for Wondrium Daily.
Michael Ormsbee is an Associate Professor in the Department of Nutrition, Food, and Exercise Sciences and Interim Director of the Institute of Sports Sciences and Medicine in the College of Human Sciences at Florida State University. He received his MS in Exercise Physiology from South Dakota State University and his PhD in Bioenergetics from East Carolina University.
