By Erica Bentz
What is a Protein?
Proteins are amazing, versatile and vital cellular working molecules. Without them, life would not exist. These molecules were first named 150 years ago after the Greek word 'proteios' meaning 'of prime importance'. Amino food proteins, whether from cereals, vegetables, beef, fish, or cheese are all altered by the body first, breaking them down into amino acids; these amino acids are arranged into specific human body proteins.
Replacing the muscle protein existing in your body is a very expensive, fuel sucking activity. Protein also produces a higher thermogenic effect compared to fats and carbs; thus you literally “burn more fuel” by eating protein.
Protein is necessary for building muscle tissue. Consuming protein in conjunction with resistance exercise helps build new muscle proteins, but protein from supplements is not “muscle in a bag/bottle” as advertisers often claim. A couch potato who takes protein supplements cannot expect gains of muscle tissue or athletic performance. Research is ongoing to determine whether sufficient protein content of fullness or delay the urge to eat.
Evidence does not support taking protein supplements to lose weight.
Amino acid supplements are often sold to athletes with promises of greater blood flow to muscles or increased muscle protein synthesis. It’s true that the essential amino acid leucine is necessary for normal protein synthesis regulation, but all complete protein sources, even a turkey sandwich or a glass of milk supply plenty of leucine. No clear benefit to muscle tissue has been demonstrated for leucine supplements, and their safety is under review.
How much Protein?
The DRI (Dietary Reference Intakes) recommended intake for protein for an average adult is 0.8 g/kg. A higher protein amount can be up to 1.2-1.7 g/kg. Recent data has suggested that increasing the amount of protein in the diet may offer a slight metabolic benefit by maintaining FFM -(define?) while decreasing body fat. Translation: keep the muscle and lose the muffin top. This effect can be further enhanced by the use of weight training. To figure out your protein need:
Find your body weight in pounds.
Convert pounds to kilograms (by dividing pounds by 2.2)
Multiply kilograms by 0.8 or ?.? kilograms to find total grams of protein needed per day.
130 lb / 2.2 = 59 kg
59 kg X 0.8 = 47 g
Layman et al. in 2005 conducted a 16 week randomized study on 48 women aged 40– 56 years. The study consisted of 5 days per week walking and 2 days per week resistance exercise (Layman et al., 2005). Supervised weight training (resistance exercise for you geeks) consisted of 7 Nautilus® weight machines with each subject performing a single 12-repetition set for each exercise.
The level of protein in the diet was varied along with carbohydrate levels, while fat was left consistent at 30% of daily calories. The higher protein group received 1.5 g protein/kg body mass/day (a 220 lb person would be eating 150 grams of protein per day), while the lower protein group received about 0.8 g protein/kg body mass/day (roughly half of the other group).
Whole-body composition was determined by dual energy X-ray absorptiometry (DXA) which has been shown to be very accurate (Van Der Ploeg, Withers, & Laforgia, 2003). What did they find? All groups lost significant body weight and displayed changes in body composition, but the higher protein and exercise group decreased their body fat by almost 6%, with almost all weight loss coming from fat and not lean body mass. This is great, since it showed a selective loss of body fat without losing muscle. Boo-yah!
The group that consumed a lower protein diet and did not exercise still lost almost 8 kg (17.6 lbs) but only 64% of their weight loss was from fat, with 2.7 kg (about 6 lbs.) loss of lean body mass. Oh no! They lost a crap-ton of weight, but that included their precious fat free mass (muscle). It can take months to years in some cases to gain 6 lbs. of lean mass. To see it vanish in a few weeks is awful. This type of diet/lifestyle combo can drop your RMR further and could send you down the wrong path. (Resting metabolic rate is the energy required by an animal to stay alive with no activity. Therefore, your real metabolic rate is always significantly higher than your RMR (resting metabolic rate). Calculating RMR is a very useful first step in calculating your real metabolic rate.
Your Resting Metabolic Rate (RMR) is one of the main contributing components of energy expenditure (around 70%).)
All is not lost now. Before you freak out completely, it should be noted that the low protein group who did exercise (walking 5 days per week and only 2 days per week of strength training) only lost 1 kg (2.2 lbs) of lean body mass. Whew!
This demonstrates that exercise, especially strength training, is extremely important if you want to hold on to your muscle tissue. Keep in mind that this study compared protein intake levels and exercise. The low protein group who did not exercise lost the greatest amount of lean tissue.
Think of it this way: your body is survival-oriented. It will do whatever it can to keep itself going. When you get into the gym and lift stuff on a regular basis, you are literally tearing your muscle tissue apart. Your body sees a large load (weights) done for many, many reps and the adaptive process springs into action…boing!
Remember, if your body wants to survive it has to rebuild this “broken” muscle tissue just in case you subject it to that particular load again in the future. (I know you will!). Your body will build bigger and stronger muscle tissue so that it is literally better at handling the loads applied to it by weight training.
Your body wants to be ready for the next assault. Fast-forward through time, over several sessions, and holding onto muscle tissue is going to become high priority. Your body is thinking, ‘Oh crap, this crazy person is going to lift stuff yet again, and this time it is a bit heavier than last time. I had better keep all this expensive muscle tissue around ‘cause I’m gonna need it!’ (I have seriously heard my body say this!)
Strength training is applying massive stimulus to hold onto muscle tissue. Whatever builds muscle will also maintain muscle. Remember that the raw material for strengthening or repairing/enlarging a muscle is dietary protein.
Protein + lifting stuff = powerful stimulus to hold onto muscle
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. By increasing your protein intake to about 1 gram of protein per pound of body weight, you dramatically reduce the rate of muscle loss on a low calorie diet. This is in an absolute worst-case where calories are cut by 60% overnight.
Walberg et al. conducted a similar study in addition to work by Mero et al. and provided further data to drive home the point that higher protein intakes combined with exercise (especially resistance training) can result in selective loss of fat accompanied by simultaneous retention of lean body tissue (Mero et al., 2010; Walberg et al., 1988). Remember, more lean body mass equates to a less significant reduction in RMR (and there may even be an improvement).