Protein is absolutely essential. It supports numerous functions in our body; immune system, anti-oxidants, growth, fertility, intestinal integrity, neurotransmitters, enzymes, repair, maintenance and function of all organs and tissue including bone. Protein is also very important for appetite regulation.
Here is an overview of critical functions: (Amino acids: metabolism, functions, and nutrition. Wu,G)
The best sources of concentrated (high percentage amino acids per food calories) and complete (contains all essential amino acids) are animal proteins. Some isolated plant proteins have all the essential amino acids, but all are isolated from seeds (rice, hemp, soy, pea), and as such are not recommended on a paleo diet.
How much protein do you need each day? You need adequate for:
- Repair and growth all body tissues and organs.
- Producing anti-oxidants, oxidants, enzymes, neurotransmitters etc. often from specific amino acids
- New muscle synthesis, for some athletes more may be an advantage.
- Maintaining muscle mass (while avoiding obesity) and strong bones, particularly as you age, there is evidence elderly require are larger amount than younger people.
- Maintaining bone strength. Protein increases calcium absorption.
- Enough to provide appetite control, via hormonal regulation, and by providing adequate amino acids to curb eating (Protein leverage hypotheses)
- Maintaining intestinal integrity
- Your particular genetic type – some people respond better to higher protein diets
The RDA in USA and NZ is 0.8g per kg body weight per day, however this is based on structural requirements (building and repair) and ignores the use of protein for energy and other functions. Optimal amounts are also likely to be higher than the RDA when we take into account the protein leverage hypothesis, and requirements for satiety. It has been suggested that amounts should be closer to 1.5 g/kg/d with an upper limit of 2 – 2.5g/kg/day. (Bilsborough & Mann, 2006)
Can you get too much protein? Yes there are downsides to eating too much. (I’ll cover more about this in another blog post) but briefly:
Excessive protein intake leads to high levels of ammonia, which is released during deamination of amino acids. The liver must then convert the ammonia to urea. A healthy person is able to convert the nitrogen from protein up a maximum to 3.8/g protein/kg/day into urea. (Rudman et al., 1973) Excess protein in the short term causes hyperaminoacidemia, hyperammoniemia, nausea and diarrhea, and even death. The maximum safe intake is suggested to be 3.56g/kg/day. (Bilsborough & Mann, 2006) A very high protein diet can also cause electrolyte imbalances. In one case study this led to death as a result of hypokalaemia.
In 1930 two men; Stefansson and Andersen, volunteered to live on just meat for an entire year, it is interesting to note the amount of protein actually eaten on average each day was 100 – 140grams, which works out to 1.6 – 2.0 gram/kg/day. Protein by calories didn’t exceed 25%, and usually stayed at 20%E. Initially one of the men ate lean meat, giving a protein intake of 4 g/ kg / day and as a consequence suffered ‘rabbit starvation’ and developed nausea and diarrhoea, this was reversed when fatty meat was eaten. (Rabbit starvation occurs with high protein, low fat and low carbohydrate diets)
Note: those with kidney disease or chirosis of the liver should eat no more than 0.8g/kg/day.
How to get the right amount of protein per day
To work out approximately the amount of protein you need you can use figure it out by calculating grams required or by using the hand method.
Based on a protein recommendation of 1.5 – 2 grams / kg / day (I recommend using your ideal body weight in kg) work out how much pure protein you need. (If you are American 1kg = 2.2lbs)
If you are 80 kg this is 120 – 160 grams per day. (80kg x 1.5) If you are choosing meat, use the charts below to work out the amount. If eating 3 meals divide protein evenly between each one. Thats 40 grams meal. If eating 4 meals divide it into 4 etc. Eat more if you are doing strength exercise or a heavy training schedule, i.e. up to 2.5 g /kg /day.
Let’s say your protein choice is chicken, 70 grams weighed chicken (cooked) contains 20 grams pure protein, you need double: 140 grams chicken contains 40 grams protein.(American translation: 30grams is approx 1 oz)
The other super easy way to get the amount right is to use your palm as a guideline. I’ve been using this method and teaching it for years. Here’s how it works, I’ll use myself as an example. Body weight (ideal) 50kg. Protein required 1.5 x 50 = 75 g per day. Or I could go to 2g x 50 = 100 grams day on heavy workout days.
I tend to have 3 meals a day. So lets say I have about 25 – 30 grams protein per meal. If I want to eat chicken, I need 100 grams chicken breast to get 30g protein. See the picture below – here is my hand with exactly 100grams chicken. It’s almost precisely the size and thickness of my palm. If I needed extra protein, I could go up to a maximum of 2 palms of protein per meal, and that would give me the extra I needed for a heavy workout schedule. I don’t though – 1 palm is plenty for me.
Just a note here – don’t get too caught up in being exact, near enough is good enough – unless you aren’t losing weight and it may be a case of:
Why choosing fatty protein might lead to excess calories and weight gain (yes – even on a low carb diet)
If you need to lose weight, it can be very easy to get a lot of extra calories choosing fatty cuts of meat. Although a higher protein, lower carb (and therefore higher fat) diet usually leads to far greater appetite control, not everyone loses weight eating until they are satisfied. Why might this happen? It is likely a result of excess calories. If you choose a fatty cut of meat, not only will you get extra calories but you can also get too much omega-6.
Here is an example – how a high fat cut of meat could give you a 1000 calorie meal
Lets say you are a smaller female and you choose a large piece of a fatty cut of meat. Say 200 grams (2 palm sizes) of pork belly:
That’s 1068 calories, 985 from fat (109grams) 989mg omega 3, 10.4grams omega 6, 20 grams protein. The protein amount is about right for a meal, but the calorie count is far in excess of needs. You also get all the recommended amount of omega 6 in just one meal. Dietary fat if not used it will be stored as body fat. (Yes – even though you are eating a low carb diet – protein also stimulates insulin secretion, and the fat has to go somewhere once eaten)
Another meal choice might be a low carb classic: 3 eggs, with 3 tablespoons of cream scrambled in 2 tablespoons of butter with a cup of spinach. 700 calories, of which 580 is from fat.
Total calories for just 2 meals: nearly 1800. Another meal, plus snacks and you won’t lose weight, you might even gain.
Now I’m not against fat in our diet,and I don’t recommend you be fat phobic, but if your protein choices include large amounts of fatty protein with more added fat, such as dollops of butter on your vegetables, coconut cream in sauces and handfuls of nuts for snacks, it just might be that you are getting too much.
Protein charts: protein in meat, seafood and dairy.
Use the following guide to choose about the right size of protein. Stick to lower / moderate fat choices, if you suspect your calories are too high. (1 gram fat = 9 calories) I recommend you also measure your portion size to get it about right for a few days. Some people in my experience overestimate portion sizes. If you use very low-fat choices, I’d recommend adding extra healthy natural fat to your meal, or you’ll get hungry.