Updated: Feb 25, 2021
Do you feel you are getting enough, too much or too little protein? What makes you think so? If you think we are consuming too much protein (or meat), I invite you to read this meaty blog post and the chances are that you may need to double your protein intake!
The Recommended Daily Allowance (RDA)
The recommended daily allowance (RDA) for both men and women is 0.8 gram of good quality protein per kilogram of bodyweight (BW). This means that for a 70 kg healthy individual, the RDA is 56g of protein.
The Truth about RDA
Recommended Daily Allowance is the MINIMUM amount to meet the BASIC nutritional requirement of most (97-98%) healthy adults. Despite the words "recommended" and "allowance", do not mistake RDA as the recommended amount for optimal health. The RDA for protein refers to the LOWEST amount of protein that must be eaten to maintain nitrogen balance*, which is a poor proxy for lean body mass in healthy individuals.
*Nitrogen balance studies are based on the assumption that muscle mass increases when the net protein (nitrogen) balance is positive, i.e. when muscle protein synthesis exceeds muscle protein breakdown.
Nitrogen Balance Studies
In fact, plenty of research says that nitrogen balance studies are unreliable in determining protein requirement. Here is a review noting that the RDA amount is significantly underestimated and the daily protein requirement can be as high as 1.2g per kg body weight . This means a person weighing 70kg should take in 84g protein per day, compared to RDA of 56g.
How Much Protein For Optimal Health
In order to achieve optimal health, I would say you need more than double the RDA amount.
If you are not fully convinced that we need that much. We can look at another USDA Guideline, the Acceptable Macronutrient Distribution Range (AMDR).
Acceptable Macronutrient Distribution Range (AMDR)
The Institute of Medicine suggests that the Acceptable Macronutrient Distribution Range (AMDR) of protein is 10% to 35% of total energy intake or daily caloric requirement. If we assume a 2,000 kcal daily energy intake, the AMDR for protein is then 200 kcal to 700 kcal or 50g to 175g (1g protein = 4 kcal).
The 10%-35% or 50g-175g is a wide range. It is because the AMDR recommendation is made in the context of a complete diet** to cover all essential nutrition and variety of nutritional goals for individuals.
**A complete diet is one where all your nutritional needs in terms calories, vitamins, minerals and micronutrient are met.
Difference between AMDR and RDA
I've done the calculation to work out what AMDR means in grams of protein(see appendix). In summary,
The AMDR for protein of 10-35% translates to
0.9g -3.2 g per kg BW or 52g to 183g of protein for reference female (57kg, 165cm, 30 yrs old)
0.9g -3.3g per kg BW or 66g to 231g of protein for reference male (70kg, 180cm, 30 yrs old).
Whereas the RDA recommends 0.8g per kg BW for both genders, i.e.
46g protein for the reference 57 kg female
56g protein for the reference 70kg male.
AMDR recommends more than RDA
You will see the lower end of the AMDR range (0.9g per kg BW) is higher than the RDA (0.8g per kg BW). This makes sense if you recall that RDA is the MINIMUM amount to meet BASIC protein requirement. You need more for optimal health.
The higher end of AMDR at 3.3g per kg BW is noticeably higher than RDA and is still considered healthy as recommended by the Institute of Medicine. You should feel comfortable and confident that doubling the RDA for protein is not only safe but gets you closer to optimal health.
Make It Simpler
If the maths is too much, go with the 2,000 kcal to approximate your total caloric intake for the AMDR. More simple, just multiply your weight in kilograms by 1 or 2 to get your protein amount in grams. Say if you weigh 60kg, you likely need 60g to 120g of protein per day. Click here for a list of food and protein content.
Benefits of Higher Protein Intake
Studies indicate that healthy adults can consume 2g per kg BW per day over long term and the tolerable upper limit can be 3.5g per kg BW per day for adults who are trained and well adapted to a high protein diet. Higher protein intake have the following benefits:
Lean body mass preservation during weight loss
Improve muscle mass and strength
Reduce risk of sarcopenia associated with ageing
You Are Unique, So Is Your Protein Requirement
Although the RDA and AMDR guidance provide some insights, the reference amounts have NOTHING to do with YOU. Because you aren't the average Joe or Jane. You are unique and so is your protein intake requirement. The amount of protein you need varies from time to time, depending on your age, gender, body weight and composition, activity level and health status. You need more protein if you are recovering from a race, an injury or an illness, or if you have a specific weight goal - gain muscle mass, or lose body fat.
Who Needs More Protein?
Athletes, children, pregnant ladies, breastfeeding mothers, and elderly need more protein for growth and development, preserving lean body mass, muscle strength, muscle function, preventing frailty and injuries.
Let's take a look at a few examples with higher protein requirement
2) Weight management
An athlete who lifts weights or trains regularly should eat a range of 1.2-1.7g of protein per kg body weight per day, or 0.5 g to 0.8 g per pound of body weight.
For example, a 70 kg athlete should aim for a protein intake of 70g - 119g per day. We should be able to obtain this much protein from our meals and without supplementation. Ideally you should spread your protein intake equally across your meals (roughly 30g protein per meal and 20g per snack). Timing your intake around your workout and before sleep may help muscle protein synthesis but this varies from individual to individual.
2) Weight Management
Whether you are seeking to gain or lose weight, you should increase your protein intake to about 2-3g per kilogram of body weight. The key lies in your lean body mass - the balance between muscle protein synthesis and muscle protein breakdown.
Weight Gain - Lean Body Mass
You may think weight gain is easy but it isn’t! Because you are thinking of fat gain but I am talking about lean muscle mass gain rather than fat storage. In general, an additional 2,300-3,600 kcal is needed to increase muscle mass by 1 pound. A randomised controlled trial on the effect of protein intake on weight gain and body composition from low, normal and high protein diets, at 5%, 15% and 25% of total caloric intake. The results showed that low protein diets produced significantly less weight gain and no increase in resting energy expenditure (similar to BMR) and lean body mass. Both normal (15%) and high (25%) protein diets produced greater weight gain, resting energy expenditure and lean body mass.
The key to healthy weight gain is to provide enough fuel and protein to support muscle growth without increasing fat storage. A general weight / lean mass gain recommendation is to increase calorie intake by 300-500 kcal per day and increase protein intake to 1.8g - 2g/ kg body weight, plus resistance training. Do not get all the calorie increase from protein, some of it should come from fat and carbohydrates. Using fat and carbohydrates as fuel can spare the body from breaking down muscle protein for fuel in the form of gluconeogenesis.
Unless you are starting from a very low protein diet, increasing dietary protein alone won't increase your lean muscle mass (LBM). The most effective way to increase LBM is through a combination of higher protein intake and resistance training, and of course with adequate recovery and quality sleep.
Weight Loss - Fat Loss and Lean Body Mass Preservation
For weight loss, everyone knows that we need to consume less calories and/or exercise more to achieve a negative energy balance. During periods of calorie restriction, muscle protein breakdown tends to maintain while muscle protein synthesis goes down.
In order to preserve muscle mass during weight loss, the nutritional focus should be on
1) fat burning - by curbing carbohydrate intake
2) preventing the body from breaking down muscle for fuel - by increasing protein intake combined with resistance training.
Further benefits of higher protein for weight loss include
Higher thermic effect of protein (20-35%) vs carbohydrate or fat (5-15%)
Protein helps to increase appetite hormones (CCK, PYY, GLP-1) to make us feel fuller for longer. (As opposed to carbohydrate which is the least satiating macronutrient and encourages the hormone insulin that signals the body to store fat.)
The general recommendation for weight loss is to reduce calorie by 500-1,000 kcal per day, increase protein up to 3g per kg body weight per day, increase exercise focus on resistance training to preserve muscle mass, and use low glycemic index foods to manage appetite.
3) Elderly Need More Protein
As we age our protein need increases. When we are around 50 years old, we need at least 1g per kg bodyweight to maintain muscle mass. If you are 50+ AND an athlete, your protein need is even higher.
Elderly can benefit from higher intakes than younger adults, especially leucine to stimulate protein synthesis, retain lean muscle mass and protein balance. Higher intake of quality protein can
Preserve lean body mass
Lower chronic inflammation on muscle
Reduce to risk of sarcopenia when combined with appropriate physical activities
Worried About Too Much Protein?
People are worried that too much protein can have an impact on kidney function. In fact, a WHO report clarifies that higher protein intake is only problematic for people with kidney disease or at risk of developing kidney failures due to diabetes, hypertension and other diseases. There is no evidence to suggest that higher protein intake can cause deterioration in kidney function in healthy people.
Higher protein intake than RDA is found to be beneficial for bone health . With respect to cardiovascular disease, a prospective cohort study of over 80,000 women suggests that replacing carbohydrates with protein may be associated with a lower risk of ischemic heart disease.
It's Hard to Overeat Protein
If you are still concerned about eating too much protein. Go and try to get 200g worth of protein in a day - which is close to 35% of your daily calorie intake or 3g for every kilogram of body weight. It's hard because protein is so satiating that you literally cannot stuff this much protein in a day. That's why there is no study being done on dietary protein exceeding this quantity.
What Does 100g of Protein Look Like in Practice?
Since you have made this far into the blog, here is a reward - what 100g of protein can look like in a day.
Breakfast - two egg omelet (12g) with 1 ounce of cheese (7g) and a glass of milk (8g) = 27g
Lunch - 150g salmon fillet (30g) = 30g
Dinner - 100g chicken breast (31g) =31g
Snacks - nuts and seeds (7g) and a cup of plain yoghurt (17g) = 24g or granola yoghurt (20g)
Protein Content in Our Food
Can you think of any other combination that will get you closer to the 100g protein range? See below a list of foods and their protein content sourced from the USDA food database.
Have you noticed that animal sources tend to provide higher protein content and less calories compared to plant sources? It is quite easy to get enough protein from animal sources without eating too many calories. For example, 300-400g of meat will give us 100g of protein for <1,000 kcal. If we try to do the same with plant foods, we will likely need >1kg of tofu, lentils and chickpeas for close to 1,500 kcal. You may decide to follow the RDA recommendation of 40g - 50g per day, which is easier to manage but remember this is the minimum and not necessarily enough to reach optimal health.
Protein Quality and Bioavailability
Having discussed protein content or quantity, what about protein quality? i.e. how much of protein in a food is digestible and available for our body to absorb? Do you want to take a guess which type of protein is most bioavailable? I'll try to address protein quality and how we measure that in my next blog post.
Thank you for reading, I hope you find the topic interesting. You can read my previous post on Protein - The Sexiest Macronutrient for the basics of protein, essential amino acids and complete protein.
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How to Estimate Your Daily Caloric Needs and convert the AMDR protein from kcal into grams.
We can work out our daily caloric needs by estimating the Total Energy Expenditure (TEE) with the Harris-Benedict Equation and Activity Factor. The Harris Benedict Equation is different for male and female and requires input parameters such as weight, height and age of the individual.
Once we know the TEE or daily calorie requirement, we can derive the kcal from protein using the AMDR range 10%-35% of TEE, then convert the kcal amount into grams (1g = 4 kcal) and compare with RDA.
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