How Much Protein During Dieting?

Courtesy of Driven Nutrition

“Yo, Bro – how much protein do I need?” I am sure you hear that question all the time.  I sure do.  While the long lengthy answer is always “it depends,” that answer is not very helpful or applicable, so let’s dive into the research and take a look.

The biggest way to divide it up is by calories.  Are you in a calorie surplus or deficit?  If you are looking to get leaner then you will (hopefully) be in a caloric deficit.   Those two caloric states are very different.

You may want to look better “in your birthday suit” or may compete in weight classes; thus, you will restrict calories to decrease body fat stores but not decrease body mass.  This is done in an attempt to gain a better strength to weight ratio which would be a competitive advantage – on the field or at the bar.

Retention of lean body mass (LBM) serves several important functions.  The primary component of LBM is skeletal muscle tissue which functions as the largest disposal site for post-prandial glucose and lipids (1) (aka burning a bunch of fats and carbs) and is the greatest determinant of our basal metabolic rate (2).  Keeping as much skeletal muscle is a key component to resist future weight gain (3) (aka you STAY looking good and kick glute max at the gym).

The downside is that hypocaloric (low calorie) diets to get leaner may result in a loss of lean body mass (including precious muscle tissue – eek) which will negatively affects your chance of maximizing your lifts and odd / ratio at the next dance night. Could you keep more muscle by just eating more protein?  If so, how much more? 

                                                                                   

The RDA – Is It Enough?

The standard Recommended Daily Allowance (RDA) of protein according to U.S. government standards is 0.8 gram per kilogram of body weight for the adult.  This protein RDA is said to meet 97.5% of the population’s needs (4).   This is roughly 60 grams of protein when you convert it – aka about how much I ate for dinner last night.

Protein intakes above this level can be considered “high-protein,” but still represent a wide range.  Research by the International Society of Sports Nutrition (ISSN) in a position stand on protein and exercise stated that,

“..protein intakes of 1.2-2.0 g/kg/day for physically active individuals is not only safe, but may improve training adaptations to exercise” (5).  

While it is beyond this article, confusion can arise since there are various methods by which the total amount of protein can be determined with many early studies using various nitrogen balance methods to determine the optimal amount. Newer methods use a tracer of some form to “track” protein around the body to see what happens.  While both of those provide information, what we really want to know is if you feed one group more protein, another group lower protein, and then do that for many weeks, does one group lose lean body mass?  The fancy propeller-head term is a chronic intervention study. To bring the research into focus, we are going to investigate studies that used an athletic/active population and intervention studies comparing high to low protein in relation to body composition since these data more directly related to the primary outcome.  Boom! 

                                                                                   

 Bring Me The Studies

#1) Layman Study

Hang on for a bit of geek-speak.  Layman et al. in 2005 (6) conducted a 16-week randomized study on 48 women aged 40–56 years using 5 days per week walking and 2 days per week of resistive exercise. The higher protein group received 1.5 g protein/kg body mass/day while the lower protein group received about half the protein at 0.8 g protein/kg body mass/day.  The higher protein and exercise group decreased their body fat by almost 6%, with almost all of it coming from fat and not lean body mass.    Yep, more pro-tein here resulted in a big loss of fat.

These data show that to drop the most body fat without much (if any) lean body mass loss, exercise and a higher protein intake of around 1.5 g protein/kg/day may be needed.   

Score: High protein 1, Low protein 0

#2) Mettler Study

The above study was in women who were active, but not high-end athletes.  “So what about the athletes?” you cry.  Glad you asked.

A study by Mettler S et al. (7) from Dr Tipton’s lab studied 20 athletes that had been exercising for over 6 months before the study started.  They also exercised on average about 360 minutes per week over 5 training sessions and were relatively lean (about 16.5% body fat).  For the study, they were divided into a control (low protein) group at 1.0 g protein/kg body mass per day while the high protein group was set at about 2.3 g protein/kg body mass per day.  After a familiarization period, all subjects were fed a hypocaloric diet of 60% of their habitual intake.  Eeeek, that is a big drop overnight.

They found that the higher protein group lost much less lean mass than the low protein control group. Protein wins again! These data match the data from Layman showing that higher protein intakes significantly reduce the loss of lean mass, despite caloric intakes of about 60% of maintenance.  In summary, even in an extreme situation where there is a fire sale on calories, more protein kept lean mass.   

Score:  Higher protein 2, low protein 0.

#3) Walberg Study

The science train rolls on.  Walberg et al. (8) conducted a similar study with the low protein group consuming about 0.8 g per kg per day and the high protein group twice that amount at 1.6 g per kg per day.  This study was quite short in nature clocking in at only 2 weeks.  They found that once again both groups lost similar amount of body fat around 2 kg.  However, both groups lost more lean body mass.  The higher protein group lost less lean body mass with a loss of 1.4 kg versus a 2.7 kg loss for the low protein group.    

The increased protein intake saw only about a 20% decrease of lean body mass compared to the low protein group.  Further evidence that increased protein during times of low calories helps preserve lean body mass. 

Score: High protein 3; Low protein 0.

#4) Mero Study

Lastly, Mero and colleagues in 2010 (9) investigated 15 women who participated in recreational resistance training and were divided into two groups with one group at an energy deficit of about 1,110 kcal/ day and other at 550 kcal/day deficit.  Both groups were fed a high protein diet at about 1.4 g/kg body mass/ day for 4 weeks.

 Both groups saw a significant reduction in weight of 2.0 kg in the 550 kcal/ day deficient and 3.8 kg in the 1,110 kcal/ day deficient group.  The weight loss was from fat mass as lean body mass stayed consistent during the study, showing once again that moderate to high levels of protein intake combined with exercise can selectively reduce body fat.

 Mero et al. (9) provides further data to drive home the point that higher protein intakes combined with exercise, especially resistance training, can result in selective loss of fat while simultaneously holding on to lean body tissue.   Performance that places a premium on strength to body weight ratio may also improve.

Final Score: High protein 4; Low protein 0.

                                                                                 

Summary – How Much Protein? 

The score is in; and the high protein intervention is a clear winner, skunking the low protein group.

How much protein does that mean you should get per day based on the studies above?  You should get around 0.7 grams / pound of bodyweight (note the studies above used metric and I converted it to English here for you non-math lovers). 

If you weigh 200 lbs, that is about 140 grams of protein per day on the low end.    

A few caveats:

• This is on the low (minimum end) to reduce loss of lean body mass when calories are low.

• Some of the subjects were recreationally trained, and none were elite athletes.

• This is based on the consumption of high quality proteins such as any meat (fish, chicken, beef, pork, etc), whey protein supplement and/ or eggs.

Go forth, and have some protein to keep your hard earned muscle!

References:

1. Petitt DS, SA Arngrimsson, KJ Cureton. Effect of resistance exercise on postprandial lipemia. J Appl Physiol. . 2003; 94(2):694-700.

2. Johnstone AM, SD Murison, JS Duncan, KA Rance, JR Speakman. Factors influencing variation in basal metabolic rate include fat-free mass, fat mass, age, and circulating thyroxine but not sex, circulating leptin, or triiodothyronine. Am J Clin Nutr. . 2005; 82(5):941-8

3. Tipton KD, RR Wolfe. Protein and amino acids for athletes. J Sports Sci. . 2004; 22(1):65-79.

4. Institute of Medicine of the National Academies. Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids (macronutrients). (Washington, DC): National Academies Press; 2002.

5. Campbell B, RB Kreider, T Ziegenfuss, et al. International Society of Sports Nutrition position stand: protein and exercise. J Int Soc Sports Nutr. . 2007; 4:8.

6. Layman DK, E Evans, JI Baum, J Seyler, DJ Erickson, RA Boileau. Dietary protein and exercise have additive effects on body composition during weight loss in adult women. J Nutr. . 2005; 135(8):1903-10.

7. Mettler S, N Mitchell, KD Tipton. Increased protein intake reduces lean body mass loss during weight loss in athletes. Med Sci Sports Exerc. . 2010; 42(2):326-37.

8. Walberg JL, MK Leidy, DJ Sturgill, DE Hinkle, SJ Ritchey, DR Sebolt. Macronutrient content of a hypoenergydiet affects nitrogen retention and muscle function in weight lifters. Int J Sports Med. . 1988; 9(4):261-6.

9. Mero AA, H Huovinen, O Matintupa, et al. Moderate energy restriction with high protein diet results in healthier outcome in women. J Int Soc Sports Nutr. . 2010; 7(1):4.