Like a Caveman, Eat More Protein!
Caveman Doctor recently received an email (whatever an email is) asking if a caveman diet contains too much protein and if it’s bad for his kidneys. Caveman doctor was very confused by this question as he is constantly surrounded by delicious and healthy sources of protein that make up the bulk of his diet. Also, he was unsure why nature would surround him with high protein foods, yet make them bad for his kidneys. Caveman Doctor likes his protein so he gave the topic a closer look.
Protein, Hunger, and Kidney Health
A caveman would never eat a food that would make him hungrier, especially since there was not always food around to eat during his time. This would be the equivalent of self-torture. Consequently, the caveman ate large amounts of protein, mostly from animal sources1-3. He ate much more protein than the average American eats nowadays. However, did this provide the caveman with benefits over present-day high-carb diets?
Looking at David’s abs, it’s pretty obvious a high protein diet gave him the physique to slay Goliath.
There are several benefits from eating more protein in your diet:
- You will be less hungry throughout the day.4
- You will eat fewer carbohydrates as they are replaced by protein.
- You will lose weight.
- You will have fewer spikes in your insulin.
- With fewer spikes and drops in your insulin, you will have less mood swings.>
Jumping right into the studies proving these points, back in 2005, 19 patients were placed on one of three diets: a low protein diet (15% content), a moderate protein (30% content) with caloric restriction, and a moderate protein (30% content) where they could eat ad libitum (as much as they wanted)4. All three diets were subpar, and at 50% carbohydrate consumption, I wouldn’t feed them to my dog. Granted, I don’t actually have a dog (caveman doesn’t have time for pets), but these types of subpar diets are standard for most nutrition studies. As for the results, the patients on the higher protein diet reported a clear increase in fullness, decrease in hunger and appetite, and a decrease in bodyweight. In fact, the patients that were allowed to eat as much as they wanted ended up eating fewer calories than the lower protein groups who were calorically restricted. I repeat, when a high-protein group was allowed to eat whatever they wanted, they actually ate less overall than a high-carb group that was calorically restricted. Similar studies confirmed the decrease in hunger and appetite with higher protein consumption5. The title of another study says it all6:
“Inadequate Dietary Protein Increases Hunger and Desire to Eat in Younger and Older Men.”
While eating more protein decreases hunger, a similar study has shown that eating more carbs and less fat actually increases appetite7. Most of us, if not all of us, know this to be true from the times when we have eaten a bunch of carbs, only to be hungry again 30 minutes later. In fact, eating more carbohydrates than fat results in a decrease in leptin (the hormone that acts on your hypothalamus to decrease hunger), an increase in ghrelin (the hormone that increases hunger), and results in an increase in appetite. In fact, as stated in the study above:
“A 15% increase in energy from dietary protein at constant carbohydrate intake produces a sustained decrease in ad libitum caloric intake that may be mediated by increased CNS leptin sensitivity and results in clinically significant weight loss.”
It is clear that protein consumption results in less appetite and hunger, unlike carbohydrate consumption that causes insulin fluctuations and increased hunger. However this does not account for all the weight loss in people on low-carb, high-protein diets. In fact, in several studies where two groups consumed similar amounts of calories with one group eating less carbs, the low-carb group lost significantly more weight8-10.
In fact, in recent prostate cancer mouse studies, when mice are placed on low-carb/high-fat diets, researchers actually have to increase their caloric intake just to keep them at the same weight as the higher-carb group11. Now this is a mouse study, but interesting nonetheless.
Once again, not only will following the ways of the caveman make you healthier, but it will make you less hungry and happier.
Unbeknownst to art historians, God was educating Adam on the benefits of a high protein diet in Michelangelo’s The Creation of Adam
High Protein Diets and Your Kidneys:
Dietary recommendations for protein range from 10-35% of dietary intake. These are also the same recommendations that suggest eating carbohydrate levels high enough to make weight loss near impossible. On a caveman diet, protein intake usually hovers at least around the higher end of these recommendations. In fact, looking at the photo below, revealing my intake the other day from Fitday, I consumed 38% of my calories from protein, and over half of my total consumption (in grams) was protein. However, this was an aberration as I tend to eat more fat and less protein than that in a given day. I did have an incredibly large steak for dinner as well as Cavewoman Doctor’s leftovers, with some of my favorite wine (if you notice the orange on the pie chart…).
Many studies exist showing no damage to the kidneys in healthy individuals on a high-protein diet12,13. One study looked at renal (kidney) function in participants on a very-low-carb, high protein diet compared with a high-carb diet, and found that kidney function was normal at one year in the high-protein group with no changes14. Moreover, there is a lack of data that shows kidney damage from high protein diets in healthy patients15.
“The concept that protein restricted diets decrease the risk of developing kidney disease in the general population is not supported by the scientific literature.”
A study from Israel almost 25 years ago compared heavy meat eaters and vegetarians, and showed that such a diet does not impair kidney function in healthy individuals16. So it appears that long term meat eaters and vegetarians have no difference in kidney function. In the article “High protein diets are not hazardous for the healthy kidneys17 the author stated:
“In summary, for individuals with normal renal function, the risks of high-protein weight loss diets are minimal and must be balanced against the real and established risk of continued obesity.”
The other important detail to consider is the fact that higher protein diets will likely lower blood pressure through the benefits of weight loss18-21, decrease rates of diabetes, and provide other health benefits as well. Since high blood pressure and diabetes are a major contributor to kidney damage, increasing protein intake may actually lead to increased kidney health in many situations.
While there is no evidence of kidney damage from a high protein diet, there is significant data that points to a Western diet contributing to kidney damage from increased obesity, diabetes, oxidative stress, and inflammation22. Also, often fructose-based foods and carbohydrates are eaten instead of protein in low-protein diets, increasing the risk of metabolic syndrome and subsequent kidney damage. Yet, while protein is not a risk for kidney damage in healthy individuals, fructose likely independently plays a large part in kidney damage and disease23. Maybe next time your doctor tells you a high protein diet will damage your kidneys, ask him or her what a high fructose diet will do to you. Once again, it’s simple logic – cavemen ate a high protein diet, so it’s highly likely it is healthy for you. But beyond intuition and logic, scientific studies back it up as well.
All studies aside, if you have impaired kidney function or established kidney disease, this may have to be watched closely and a high protein diet may be more difficult to follow15. As always, please consult your physician for individually tailored medical advice.
Eat foods with protein and eat a lot of it (at least a third of your diet). It will leave you less hungry, leaner, and healthier. It’s as though a high protein diet is telling you “you’re getting adequately nourished”, and as a result, your body doesn’t leave you hungry and asking for more. Protein is our bodies’ building block, and therefore it makes sense to make sure you eat enough of it.
Studies have shown that high protein diets are safe for people without kidney problems. Not only are they safe, but they are helpful, especially for both weight loss and maintaining a healthy weight. A high-carb diet, on the other hand, promotes high blood pressure and diabetes, two things PROVEN to hurt your kidneys.
Once again, Mother Nature set up the clear pathway to health and happiness for the caveman. All he had to do was follow it.
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18. Brehm BJ, Seeley RJ, Daniels SR, D’Alessio DA. A randomized trial comparing a very low carbohydrate diet and a calorie-restricted low fat diet on body weight and cardiovascular risk factors in healthy women. J Clin Endocrinol Metab. Apr 2003;88(4):1617-1623.
19. Foster GD, Wyatt HR, Hill JO, et al. A randomized trial of a low-carbohydrate diet for obesity. N Engl J Med. May 22 2003;348(21):2082-2090.
20. Freedland SJ, Mavropoulos J, Wang A, et al. Carbohydrate restriction, prostate cancer growth, and the insulin-like growth factor axis. Prostate. Jan 1 2008;68(1):11-19.
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