I have heard countless times, whether in magazines, from YouTubers, vegans and even health professionals that a high protein diet is supposedly “unhealthy” and harmful for the kidneys.
Is there any truth to this claim?
Do high protein (hp) diets really ‘damage, how much is too much and what would be “optimal” body composition vs. just wanting to live a long and healthy life?
First lets touch on what protein actually is.
Protein is one of our three macronutrients (technically 4 if you count alcohol), and it is one of only two essential macronutrients (the other one being fat).
Protein is an ‘essential part of all living organisms, especially components of body tissues such as muscle, hair, etc and as enzymes and antibodies’, according to the Oxford Dictionary (1). Our body cannot produce it on its own, therefore it needs to be ingested (by way of food).
Protein is actually present in most foods (for example white rice, potatoes, bananas… of course only in very small quantities compared to higher protein foods such as chicken breast, dairy, eggs etc.).
That means we all NEED protein and we all CONSUME protein.
The question is just how much for whom and for what goal and are there consequences if we eat too much (or too little)?.
In this post I am going to dissect some studies on the topic to give you a better guideline for your aesthetic goal.
Then I will go into how this may differ if you are simply chasing longevity vs aesthetics.
High vs. Low Protein
In this study 17 healthy, aspiring female physique athletes were split into a high protein diet group (2.5g of protein per day per kg) or a low protein group (0.9g per kg). They also participated in an 8 week resistance training program.
What they found: After the 8 weeks the high protein group showed a significantly higher increase in lean body mass and a significantly higher decrease in fat mass compared to the low protein group.
Strength (back squat and deadlift) increased to the same degree in both groups.
Their conclusion: For female physique athletes a higher protein diet is more advantageous for increasing lean body mass in conjunction with a resistance training program than a lower protein diet.
Limitation to the study: There were no parameters placed on carb or fat intake for each group.
What that means for you: Consuming more protein might not necessarily be beneficial for your strength gains, but could be helpful for increasing lean body mass and decreasing fat mass.
How a High Protein Diet Affect Health Markers and Body Weight After a Year
14 healthy resistance trained men took part in this one year cross-over study.
They ate what they ‘normally’ would eat for 2 months and then switched to a high protein diet (at 3g/kg/d) for 4 months and then vice versa. For each one of them the protein significantly increased during the high protein phase compared with their ‘regular’ diet.
What they found: There were absolutely no harmful effects on measures of blood lipids, as well as liver or kidney function AND even though they continued to eat their regular diet PLUS extra protein on top (so a caloric surplus through protein consumption) there was NO increase in fat mass!
Their conclusion: A high protein diet over the course of a year did not show any negative effects in healthy resistance trained males and even though they were in a caloric surplus through protein no fat mass was gained.
What that means for you: If you are an active and healthy individual, a h.p. diet has no negative effects on your health. It could also mean that potentially a caloric surplus through protein won’t necessarily lead to weight gain, as it is harder to store as fat.
Consuming a High Protein Diet
In this study 30 healthy resistance- trained individuals were randomly assigned either to a control group (maintaining the same training and diet) or a high protein diet with 4.4g of protein per kg of body weight, while keeping the same fat and carb intake over the course of the 8 week trial (so essentially a caloric surplus through protein).
What they found: There were no significant changes over time between groups for body weight, fat mass, fat free mass or percent body fat.
Conclusion: Even as much as 5.5 times the recommended daily allowance of protein (5) showed no increase in fat mass in resistance trained individuals, even in a calorie surplus.
The Effects of Overfeeding
This research review was written with the hypothesis in mind that protein overfeeding (so a calorie surplus through protein) may not result in a gain in body weight or fat mass.
What they found: It is clear that overfeeding on carbs or fat has a different effect on body composition than overfeeding on protein. It seems that it is very difficult for the body to “transcribe” into fat and so it is very unlikely to be stored as such especially if you combine it with resistance training.
However, there is probably an upper limit where additional protein intake doesn’t result in gaining addition lean body mass. Since high protein diets have shown not to have a negative effect on kidney, bone and metabolic health in athletes, the recommendation in this review is that someone who wants to put on lean body mass could actually consume more than just 2.2g/kg/d, but more like 3.4g/kg/d, but it is unsure if more than that would provide any additional benefits.
Their conclusion: ‘Evidence suggests that dietary protein may be the key macronutrient in terms of promoting positive changes in body composition.’
What that means for you: If you are keen to experiment on yourself and you want to see how far you can push your own protein intake (in a calorie surplus), observing your weight and body fat percentage, you can easily push your protein intake closer to 3g/kg/d and see what difference it will make.
High Protein Diets and Weight Loss
In this study they used 113 overweight individuals. For 4 weeks they followed a very-low energy diet, losing between 5-7% of body mass. After that there was a monitored 6-month weight management period. The subjects were split into a protein group and a control group. The protein group received 30g of extra protein in addition to their usual diet (they consumed 18% of their energy through protein compared with 15% for the non-protein group).
What they found: During the weight management phase the protein group showed a lower weight regain and a decreased waist circumference compared with the other group.
The weight regain in the protein group consisted of only lean body mass, whereas the other group also gained fat back.
Their conclusion: Those who consumed more energy through protein regained less weight during a 6 month weight management phase after a weight loss diet. The weight regained in the protein group was only fat free mass and fat mass continued to decrease in the weight maintenance phase, which means body fat percentage continued to decrease.
What that means for you: Even in a weight maintenance phase you may benefit from a h.p. diet in order to continue decreasing body fat and increasing lean body mass.
Effects of a Higher Protein Diet in Older Women
54 overweight and obese women (aged 65 +/-5) participated in this 14 week study. They were split into three groups. They all received a supervised resistance based training program. One group continued with their normal diet, the other one followed a high protein diet and the last one a high carb diet.
What they found: All groups showed significant improvements in strength, muscular endurance, balance… but the h.p. diet group experienced significantly more weight loss, fat loss and retention of lean body mass.
Their conclusion: Older, otherwise healthy women who follow a h.p. diet and participate in resistance training experience can experience greater weight loss, fat loss and body fat percentage and waist circumference than women who follow a high carb diet. Even at that age, weight loss can be achieved without losing too much lean body mass or reduction in BMR (basal metabolic rate). The high protein group also experienced better management of blood glucose and appetite-related hormones.
More research is needed for individuals with medical conditions.
What that means for you: Older, healthy individuals who are looking to change body composition, it is also recommended to consume a higher portion of protein in their diet and to engage in resistance training.
To sum it up for aesthetic goals:
Overall, research is pretty clear on the fact that if you are an active, healthy individual with no preexisting medical conditions, most of the time a diet high in protein (at least 0.8g of protein per pound of body weight) is advantageous for building and retaining lean muscle mass, losing fat mass and maintaining weight after a weight loss period.
Now I want you to take something in consideration:
Optimal protein consumption for aesthetics and for longevity are not the same!
Meaning, even though a h.p. diet may not be harmful for your body, if your goal is simply to live as long and healthy as possible and you don’t care too much whether you look lean or muscular, most recommendations point towards something similar to a “blue zone diet”.
What the heck are the blue zones you ask (8)? The blue zones are 5 areas throughout the world where on average people live the longest (Sardinia/ Italy, Okinawa/ Japan, Loma Linda/ California, Ikaria/ Greek Island, Nicoya Peninsula/ Costa Rica).
While they are all very different cultures with different diets, there are a few things that they have in common (for example: moderate regular physical activity, they have a purpose in life, reduced stress, moderate alcohol intake, engagement in spirituality/family life and social life).
In addition to that, they have an overall moderate caloric intake and a mostly plant based diet, very little processed foods. This probably doesn’t come as a surprise to you.
What might come as a surprise, however, is that if simply living a long life is your goal, just like the people living in the blue zones, you may actually want to limit your protein intake to only about 20% of your overall caloric intake or less. Animal proteins in particular should be limited to just about a serving per day, making legumes and whole grains the more preferred source of protein, as well as fish 3-4 times per week.
The reason for this is manifold:
→ Protein is in fact harder to digest than the other two micronutrients (hence why it has a higher thermic effect of food). Therefore, it is more strenuous for the digestive tract to constantly consume high amounts of protein (consider that every little detail adds up over the course of the years!).
→ Animal protein in particular has been linked to elevations in IGF-1, a maker that has been highly correlated with lower life spans compared to those who consume lots of vegetables and fruits (10).
→ By consuming most of your calories from plant products you are automatically consuming more antioxidants, which aid the body in fixing some of the damage that contributes to aging.
→ More vegetables also usually mean a happy gut microbiome, which normally automatically means a healthier immune system.
However, if you are overweight or obese, the health benefits of losing the additional fat are going to outweigh the “negative” effects of consuming a diet higher in protein.
SO that means this lower protein, blue zone – style diet, is really only for someone with healthy body fat levels and is not aiming for a lean, toned physique.
What if you want both?? Great aesthetics AND to live long and healthy??
Easy: Find the middle ground!
→ Base your diet 80-90% on WHOLE FOODS. Why not 100%? Because perfectionism is the enemy! We don’t live in a bubble and chances that you would be able to adhere to a diet with not a single processed food ever are very slim. So rather than you binging out occasionally, we rather recommend allowing a bit of wiggle room for some ‘fun foods’ here and there that keep you sane, without ruining your health or your aesthetic goals.
→ Pay attention to QUALITY when it comes to meat! The 1$ precooked sausages in the chilled section that don’t even go bad if you leave them on the table counter for a week are probably not the best choice here. Buy grass fed and organic if possible, wild caught fish and free range eggs as well as GMO free protein powders etc. If this is not in your budget, don’t freak out. Do the best that you can. Stressing over things like that will likely have a worse impact on your health than just eating “non-organic” chicken breast does.
→ Don’t overdo a good thing. For longevity AND aesthetics, it is likely a good idea to stay within 0.8-1.2g of protein per pound of body weight per day. If you are leaning more in one direction than the other (longevity vs aesthetics) make your own call, push in either direction (less or more protein) to see how you feel with it.
Also, the vast majority of people who want to change their body composition, gain strength and lean out think they are consuming enough protein, but they are not. That is why we recommend tracking your macros and calorie intake at least for a little while to gain some awareness and education. To learn more about the validity of macro based diets check out this blog here.
Some helpful tips when you are trying to increase your protein consumption:
→ Don’t go from 50g to 150g from one day to the next, your digestive track will have a hard time to keep up with that. Slowly increase your intake over time and monitor bloating etc.
→ Keep shakes and bars to a minimum and aim to get most if not all your protein from whole foods.
→ An easy way to up your protein intake is by simply increasing the portion size in one meal (for example from 4 to 6 oz per meal).
→ Alternatively you could add another meal/snack/shake if you are having a hard time eating larger meals.
→ Focus on LEAN sources most of the time. Salmon and bacon are delicious, but they also come with a lot of fat, which likely makes it hard for you to stay within your macros. Lean ground beef or bison, chicken breast, a lean cut of steak, white fish, seafood, turkey, low fat dairy products, egg whites… should in combination with some fatty proteins (whole eggs, fattier cuts of beef/chicken, full fat dairy etc) most likely make up the majority of your protein (unless you are vegan, then check out this bog on ‘how to get jacked as a vegan’).
→ Spread the macro across your meals evenly. Not only would it be super difficult to eat (and digest) 100g of protein in one sitting, if you have been low on it in your other meals, it is also not the most advantageous thing for muscle protein synthesis (MPS). Even if in the end of the day it does come down to total daily consumption, the most optimal thing for building lean muscle and from a digestion perspective is to consume relatively equal amounts in all meals.
→ The previous point also becomes even more important as we age. We need to consider something called “Leucine Threshold”. Leucine is an amino acid that stimulates muscle protein synthesis. We need to consume a certain amount of protein in one sitting before we actually stimulate this MPS. While there is no exact value where you can say “now synthesis starts”, most people should probably consume at least 20-25g of protein with each meal in order to hit that threshold. This threshold goes up as we age (as muscle breakdown goes up), hence so does the amount of protein we should eat per meal.
Lastly, I just want to emphasis again that this is based on you being an otherwise healthy individual. If you have pre-existing kidney or health issues these guidelines could be completely off so do not take this as medical advice.
This blog is written by Lisa Franz, a Boom Boom Performance Nutrition Coach. Lisa has her BEXSc (Bachelors of Sports and Exercise Science), CF-1, NCI (Nutrition Coaching Certification), Hormone Specialist Certification, Yoga, Massage, and still working on more. She’s forever engulfed in the science and study of the human body, which shows in her passion filled coaching and writing. Click Here Now to Apply For Coaching, With Lisa.