Saw this great article regarding protein intake and muscle sparing. Figured I would post it here for all to read.
The Real Truth about Protein and Weight Loss
With books like The Dukan Diet and The Paleo Diet riding high in the charts, the subject of protein and weight loss has hit the headlines once again.
There’s no other nutrient that seems to inspire as much debate as protein. Bodybuilders, figure competitors and fitness models claim that extra protein over and above the RDA (Recommended Daily Amount) is essential to help preserve muscle mass during weight loss.
The argument from many nutritionists is that the RDA provides enough protein to meet the needs of most people. They say that extra protein is unnecessary and simply puts an extra burden on the kidneys.
Does protein help weight loss? How much protein should you be eating? And how does exercise influence your protein needs?
Despite the controversy, thereâ??s a growing body of research to show that a protein-rich diet is the diet of choice for anyone who wants to lose weight without losing muscle tissue.
Some very interesting research in this area comes from a group led by Dr. Donald Layman, professor of food science and human nutrition at the University of Illinois. Laymanâ??s work shows the value of dietary protein for muscle preservation during a period of weight loss.
In a trial carried in the Journal of Nutrition, Laymanâ??s research team assigned a group of overweight women to one of two diets for 10 weeks .
The first group consumed a low-protein diet (68 grams of protein per day, or 16% of total calories).
Group two followed a moderate-protein diet (125 grams of protein per day, or 30% of total calories).
Both diets provided similar levels of both calories (1700 calories) and fat (50 grams per day).
The low-protein diet was representative of typical dietary recommendations for weight loss, with around 60% of total calories derived from carbohydrate, 15% from protein and 25% from fat.
After following the diets for 10 weeks, the low-protein group lost 15 pounds in weight, while the moderate-protein group lost an average of 17 pounds.
So, while the moderate-protein group did lose slightly more weight, this difference wasnâ??t statistically significant.
These results wonâ??t come as any great surprise to most readers â?? when people are fed the same number of calories under controlled conditions, they tend to lose about the same amount of weight once early fluid losses have been taken into account.
But if both groups lost the same amount of weight, how did the extra protein help weight loss?
There’s a big difference between weight loss and fat loss. When body composition was measured using dual X-ray absorptiometry (DEXA), a relatively accurate way to track changes in body composition, women in the moderate-protein group lost an average of 12 pounds of fat, compared with 10 pounds of fat in the low-protein group.
More interesting still, the loss of muscle was around 30% greater for women in the low-protein group compared with those in the moderate-protein group.
In other words, increasing daily protein intake from 68 to 125 grams per day with a reduction in carbohydrate intake led to a 20% greater rate of fat loss and an increase in the preservation of lean muscle.
When changes in body composition were expressed as a ratio of fat/lean loss (shown below), the higher protein diet partitioned a significantly greater percentage of the weight loss to body fat while sparing lean tissue.
I should point out that the women taking part in the study were not following a structured exercise program. What happens when exercise is included?
Is the effect of protein on muscle preservation during weight loss amplified with the addition of resistance exercise? Or does resistance exercise reduce the need for extra protein?
A follow-up study, again led by Professor Layman, gives us some answers .
In the study, researchers compared the effects of a moderate-protein diet against a low-protein diet, but this time it was combined with exercise. Both diets contained 1,700 calories, 30% of calories from fat, and about 17 grams of fiber.
However, women on the moderate-protein diet replaced foods high in carbohydrate (e.g. breads, rice, cereal, pasta, and potatoes) with protein-rich foods (e.g. meats, dairy, eggs, and nuts) to get about 30% of their total calories from protein (1.6 grams of protein per kilogram of body weight).
Women on the high-carbohydrate diet ate about half that amount of protein (0.8 grams per kilogram of body weight) and got about 60% of their daily calories from carbohydrate.
The women were then split into two further exercise groups. Exercise in group one involved voluntary “light walking activity.” Women in this group averaged about 100 minutes per week of added exercise.
While group two walked a minimum of five days per week, they also did resistance exercise (30 minutes of weight training) twice weekly. The exercise was supervised and averaged 200 minutes or more each week.
After four months, both groups of dieters lost weight. Not surprisingly, body composition tests (DEXA) show that women who did resistance exercise lost less muscle and more fat.
High-protein dieters who did resistance exercise group lost an average of 22 pounds and less than one pound of muscle.
High-carbohydrate dieters who also did resistance exercise group lost an average of 15 pounds. But they also lost over 2 pounds of muscle.
In other words, nearly 100% of the weight lost in the moderate-protein group was fat, with virtually no loss of muscle. However, only 85% of the weight lost in the low-protein group came from fat with around 15% coming from muscle.
What about the group who only did the walking?
The high-protein dieters in this group lost an average of 19 pounds. However, over 4 pounds came from muscle. The high-carbohydrate group lost 17 pounds, but nearly 6 pounds came from muscle.
“Both diets work because, when you restrict calories, you lose weight. But the people on the higher-protein diet lost more weight,” says Professor Layman.
“There’s an additive, interactive effect when a protein-rich diet is combined with exercise. The two work together to correct body composition; dieters lose more weight, and they lose fat, not muscle.”
In other words, it was the combination of protein, cardiovascular and resistance exercise that provided the greatest benefits in terms of fat loss.
As well as helping to preserve muscle, protein plays another important role during weight loss.
Studies show that protein does a better job at filling you up than carbohydrate or fat. Eat a protein-rich breakfast, for example, and chances are that you won’t eat as much food for lunch.
The figure below is from a University of Washington study where dieters were told to eat roughly twice as much protein as normal . The circles at the top represent daily calorie intake, while the diamonds at the bottom represent body weight.
As you can see, eating more protein led to a spontaneous reduction in calorie intake that lasted for the length of the study. In fact, calorie intake dropped by an average of 441 calories per day.
After 12 weeks, the test subjects had lost about 5 kilograms (12 pounds). Considering they did no exercise, losing an average of 1 pound per week is a decent result.
So how much protein should you eat each day if you want to hold on to the muscle you have?
Most recommendations for protein intake are based on body weight, such as the popular recommendation to eat one gram of protein per pound of bodyweight.
But for someone who is very overweight, this method drastically overestimates their protein requirements.
Let’s say you have an obese man who weighs 300 pounds. Do you still give him one gram of protein per pound of bodyweight?
This comes to 300 grams of protein per day, an amount that’s far more than he actually needs and a level that’s going to be very difficult to reach without spending all day in the kitchen.
Instead, I recommend that you aim for 1 gram of protein for every pound of your TARGET body weight. In other words, if you want to weigh 170 pounds, you’ll eat 170 grams of protein per day.
If you’re someone who is already relatively lean (less than 14% body fat) and you want to get VERY lean (less than 10% body fat), you may need a little more protein. In this case, somewhere in the region of 1.25 grams per pound of your target bodyweight is about right.