Is The Paleo Diet Healthy?

Written by Dr. Steve Chaney on . Posted in Paleo Diet

Did Cave Men Have The Secret For A Longer, Healthier Life?

Author: Dr. Stephen Chaney

 

the paleo dietIt seems like everyone you talk to is following the Paleo diet or knows someone who is following the Paleo diet. It is the latest diet fad. But, is the Paleo diet healthy?

If you have been around for a few years, like me, you have seen lots of fad diets come and go. They are immensely popular for a few years. Then people discover their weight loss was temporary or they aren’t any healthier, and the diet slowly fades into obscurity.

Is the Paleo diet one of those fad diets that will fade into obscurity, or is it a healthy diet that will stand the test of time? A lot has been written about the Paleo diet, both pro and con. I have analyzed the science behind the claims and counter-claims so I can bring you the truth about the Paleo diet.

 

Unicorns And the Paleo Diet

 

the paleo diet and unicornsI titled this section “Unicorns and the Paleo Diet” because both are myths. In fact, the Paleo Diet is based on several myths.

Myth #1: Our ancestors all had the same diet. What we currently know as the Paleo diet is based on the diets of a few primitive hunter-gatherer societies that still exist in some regions of the world. However, when you look at the data more carefully, you discover that the diet of primitive societies varies with their local ecosystems.

The “Paleo diet” is typical of ecosystems in which game is plentiful and fruits and vegetables are less abundant or are seasonal. In ecosystems where fruits and vegetables are abundant, primitive societies tend to be more gatherers than hunters. They eat more fruits and vegetables and less meat.

The assumption that starchy foods were absent in the paleolithic diet is also a myth. For some primitive societies, starchy fruits or starchy roots are a big part of their diet. In short, our paleolithic ancestors ate whatever nature provided.

Myth #2: Our genetic makeup is hardwired around the “paleolithic diet.” In fact, humans are very adaptable. We are designed to thrive in a wide variety of ecosystems. It is this adaptability that has allowed us to expand to every nook and cranny of the world.

For example, the enzymes needed to digest grains are all inducible, which means the body can turn them on when needed. Our paleolithic ancestors may not have eaten much grain, but we can very quickly adapt to the introduction of grains into our diet.

Myth #3: Our paleolithic ancestors were healthier than modern man: It many respects, the paleolithic diet is healthy, as I will discuss below. However, we need to remember that our paleolithic ancestors rarely lived past 30 or 40. They simply did not live long enough to experience degenerative diseases like heart disease and cancer. We have no idea whether a diet that served our paleolithic ancestors well will keep us healthy into our 70s, 80s and beyond.

However, just because the Paleo diet is based on mythology does not mean that it isn’t healthy. Let’s look at the pros and cons of the Paleo diet.

 

The Pros Of The Paleo Diet

 

the paleo diet thumbs upThere are lots of things to like about the Paleo diet. For example:

  • It eliminates sodas, fast foods, processed foods, sugar and salt. Any diet that does that is a vast improvement over the typical American diet.
  • It emphasizes fresh fruits and vegetables, another big improvement over the typical American diet.
  • It has a healthier profile of fats than the other low carb diets. It favors grass-fed beef, wild-caught fish, and free-range chicken, so it has less saturated fat and more omega-3s. It also emphasizes healthy oils such as olive, walnut, avocado, and flaxseed. In this regard, it is clearly healthier than the other low carb diets. It does include coconut oil, which is a concern. As I have pointed out in a previous article, Is Coconut Oil Bad For You, there is no convincing evidence that coconut oil is healthy.
  • It emphasizes use of unrefined or extra virgin oils rather than refined oils. That is a plus for most oils because the unrefined oils are more likely to contain antioxidants and beneficial phytonutrients. It is, however, a concern for coconut oil because the unrefined oil is more likely to contain cancer-causing aflatoxins.
  • Like most other restrictive diets that eliminate processed foods, it can give short term weight loss, although long term weight loss is less certain.

 

The Cons Of The Paleo Diet

the paleo diet thumbs down

There are, however, some concerns about the Paleo diet. Other experts have commented on the cost and difficulty in following the diet, especially if you eat out a lot, so I won’t comment on those aspects here. I will stick with nutritional concerns with the Paleo diet. For example:

  • It eliminates cereal grains, legumes, and dairy. I am always concerned with the nutritional adequacy of diets that eliminate whole food groups. For example:
    • Dairy is a major source of calcium and vitamin D in the American diet. Eliminating dairy has the potential to increase the risk of osteoporosis.
    • Whole grains, legumes and dairy are important sources of magnesium. Magnesium deficiency has the potential to increase the risk of heart disease, among other things.
    • Most Americans are already not getting enough of these nutrients in their diet. We can scarcely afford to eliminate foods that are good sources of these nutrients.
    • It is possible to carefully design a Paleo diet so these nutrients are provided by other foods, but most people don’t carefully design their daily diet.
  • It recommends increasing protein intake to 19 – 35% of calories. Because legumes have been eliminated, the increased protein intake is coming almost entirely from animal protein, primarily red meat and fish. I will discuss the health concerns with red meat below. However, there is a practical consideration as well. Grass-fed beef is not always available, especially if you eat out frequently. If you are not eating grass-fed beef, you will be taking in more saturated fats and the healthier fat profile of the Paleo diet will disappear.
  • It has been influenced by the recent hype about health benefits of coconut oil. Coconut oil is just one of several oils that are recommended. However, if you look on the internet today, coconut oil is featured in almost every Paleo diet recipe. Until we have definitive evidence whether or not coconut oil is healthy, I would emphasize the other oils recommended for the Paleo diet, and use coconut oil sparingly.
  • There are no studies showing the Paleo diet is healthy long term. In contrast, there are long term studies showing that Vegan, Mediterranean, and DASH diets decrease the risk of heart disease, diabetes, some cancers and Alzheimer’s.

 

Concerns About Red Meat

the paleo diet red meatThe International Agency For Research On Cancer (IARC), the agency created by the WHO to set international standards for cancer risk, has designated red meat as a class 2a carcinogen. That designation means that there is probable cause to believe that it increases cancer risk in humans. The evidence is best for increased risk of colon cancer and breast cancer, although there is some evidence that it may increase risk of pancreatic and prostate cancer.

The increased cancer risk of red meat does not seem to be due to its fat content, so grass fed beef is just as likely to increase cancer risk as conventionally produced beef. There are multiple proposed mechanisms for this effect:

  • When fat and juices from the meat drip onto an open flame, carcinogenic polyaromatic hydrocarbons are formed that stick to the surface of the meat. This can be reduced, but not eliminated, by lower fat meat choices.
  • When red meats are cooked at high temperatures, amino acids in the meat combine with a compound called creatine, which is found in all red meats, to form carcinogenic heterocyclic amines. This can be reduced by cooking the meat at lower temperatures.
  • Heme iron, which is found in all red meats, combines with other component of our diet to form carcinogenic N-nitroso compounds in our intestines.
  • People who eat high meat diets have an entirely different population of intestinal bacteria than people who eat no meat. Several recent studies suggest that the intestinal bacteria of meat eaters are more likely to convert the foods we eat into chemicals that increase the risk of cancer and heart disease.

To be clear, red meat is a probable carcinogen and we aren’t sure of the exact mechanism(s) that cause this carcinogenicity. We do not yet have definitive evidence that red meat causes cancer. However, there is good reason to be cautious about how much red meat we consume.

The good news is that the antioxidants, fiber and phytonutrients found in fruits and vegetables can block most of these cancer-causing pathways. That means that small amounts of red meat in a largely plant-based diet may not be as concerning. Specifically, an ounce of red meat in a large green salad or stir fry is much less likely to increase your cancer risk than a 6 ounce steak.

Is The Paleo Diet Healthy?

 

As mentioned above, there is a lot to like about the Paleo diet. It is healthier than the typical American diet, and it is healthier than most of the low carb diets. I have concerns about the nutrition adequacy of any diet that eliminates whole food groups and the heavy emphasis on red meat. There is also no proof that the Paleo diet is healthy long term.

Since the restrictions of the Paleo diet are based on mythology rather than science, my recommendation would be to loosen the restrictions on whole grains, legumes & low-fat dairy, and rely less on red meat as a protein source. If you did that, the diet would more closely resemble the Mediterranean and DASH diets, which we know are healthy long term.

 

The Bottom Line

 

  1. The Paleo diet is based on a myth.
    • Our paleolithic ancestors did not eat a single diet. They followed a variety of diets depending on the foods most available where they lived.
    • Our bodies are not genetically hardwired for a single diet, but are designed to adapt to a wide variety of foods. For example, all of us have the enzymes needed to digest grains, and those enzymes are inducible.
    • We don’t know whether the paleolithic diet is healthy. The average lifespan of our paleolithic ancestors was in the range of 30 to 40 years. We have no idea whether a diet that served our paleolithic ancestors well will keep us healthy into our 70s, 80s and beyond.
  2. However, the fact that the Paleo diet is based on a myth does not make it unhealthy. In fact, there is a lot to like about the Paleo diet.
    • It eliminates sodas, fast foods, processed foods, sugar and salt which makes it much healthier than the standard American diet.
    • It emphasizes fresh fruits and vegetables, which is also an improvement over the standard American diet.
    • If features a relatively healthy profile of fats, which makes it healthier than most other low carb diets.
    • It favors unrefined or extra virgin oils, which are generally healthier than highly processed oils. The exception is coconut oil because unrefined coconut oil may be contaminated with aflatoxins.
    • It can give short term weight loss, although long term weight loss is uncertain.
  3. However, there are concerns about the long-term safety of the Paleo diet. The minor concerns are:
    • The elimination of whole grains, legumes, and dairy from the diet creates the potential for nutritional deficiencies that can have long-term health consequences. It is possible to carefully design a Paleo diet so these nutrients are provided by other foods, but most people don’t carefully design their daily diet.
    • Most of the recipes you find on the internet for the Paleo diet use coconut oil. This is a concern because we don’t know whether coconut oil is healthy. My recommendation would be to substitute the healthier oils that are also part of the Paleo diet.
  4. More serious concerns are:
    • The heavy reliance on red meat. Red meat is classified as a probable carcinogen, potentially increasing the risk of colon cancer, breast cancer, pancreatic cancer and prostate cancer. The potential carcinogenicity of red meat is not reduced by substituting grass-fed beef for conventionally produced beef.
    • There are no clinical studies showing the Paleo diet is healthy long term. In contrast, there are long term studies showing that Vegan, Mediterranean, and DASH diets decrease the risk of heart disease, diabetes, some cancers and Alzheimer’s.
  5. Because the restrictions of the Paleo diet are based on myth rather than science, there are simple work arounds for the concerns. If one were to loosen the restrictions on whole grains, legumes and low-fat dairy & reduce the reliance on red meat, you would have a diet closer to the Mediterranean and DASH diets, which we know are healthy long term.
  6. For details, read the article above.

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

 

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A Low Carb Diet and Weight Loss

Posted January 15, 2019 by Dr. Steve Chaney

Do Low-Carb Diets Help Maintain Weight Loss?

Author: Dr. Stephen Chaney

 

low carb dietTraditional diets have been based on counting calories, but are all calories equal? Low-carb enthusiasts have long claimed that diets high in sugar and refined carbs cause obesity. Their hypothesis is based on the fact that high blood sugar levels cause a spike in insulin levels, and insulin promotes fat storage.

The problem is that there has been scant evidence to support that hypothesis. In fact, a recent meta-analysis of 32 published clinical studies (KD Hall and J Guo, Gastroenterology, 152: 1718-1727, 2017 ) concluded that low-fat diets resulted in a higher metabolic rate and greater fat loss than isocaloric low-carbohydrate diets.

However, low-carb enthusiasts persisted. They argued that the studies included in the meta-analysis were too short to adequately measure the metabolic effects of a low-carb diet. Recently, a study has been published in the British Medical Journal (CB Ebbeling et al, BMJ 2018, 363:k4583 ) that appears to vindicate their position.

Are low carb diets best for long term weight loss?

Low-carb enthusiasts claim the study conclusively shows that low-carb diets are best for losing weight and for keeping it off once you have lost it. They are saying that it is time to shift away from counting calories and from promoting low-fat diets and focus on low-carb diets instead if we wish to solve the obesity epidemic. In this article I will focus on three issues:

  • How good was the study?
  • What were its limitations?
  • Are the claims justified?

 

How Was The Study Designed?

low carb diet studyThe investigators started with 234 overweight adults (30% male, 78% white, average age 40, BMI 32) recruited from the campus of Framingham State University in Massachusetts. All participants were put on a diet that restricted calories to 60% of estimated needs for 10 weeks. The diet consisted of 45% of calories from carbohydrate, 30% from fat, and 25% from protein. [So much for the claim that the study showed low-carb diets were more effective for weight loss. The diet used for the weight loss portion of the diet was not low-carb.]

During the initial phase of the study 161 of the participants achieved 10% weight loss. These participants were randomly divided into 3 groups for the weight maintenance phase of the study.

  • The diet composition of the high-carb group was 60% carbohydrate, 20% fat, and 20% protein.
  • The diet composition of the moderate-carb group was 40% carbohydrate, 40% fat, and 20% protein.
  • The diet composition of the low-carb group was 20% carbohydrate, 60% fat, and 20% protein.

Other important characteristics of the study were:

  • The weight maintenance portion of the study lasted 5 months – much longer than any previous study.
  • All meals were designed by dietitians and prepared by a commercial food service. The meals were either served in a cafeteria or packaged to be taken home by the participants.
  • The caloric content of the meals was individually adjusted on a weekly basis so that weight was kept within a ± 4-pound range during the 5-month maintenance phase.
  • Sugar, saturated fat, and sodium were limited and kept relatively constant among the 3 diets.

120 participants made it through the 5-month maintenance phase.

 

Do Low-Carb Diets Help Maintain Weight Loss?

low carb diet maintain weight lossThe results were striking:

  • The low-carb group burned an additional 278 calories/day compared to the high-carb group and 131 calories/day more than the moderate-carbohydrate group.
  • These differences were even higher for those individuals with higher insulin secretion at the beginning of the maintenance phase of the study.
  • These differences lead the authors to hypothesize that low-carb diets might be more effective for weight maintenance than other diets.

 

What Are The Pros And Cons Of This Study?

low carb diet pros and consThis was a very well-done study. In fact, it is the most ambitious and well-controlled study of its kind. However, like any other clinical study, it has its limitations. It also needs to be repeated.

The pros of the study are obvious. It was a long study and the dietary intake of the participants was tightly controlled.

As for cons, here are the three limitations of the study listed by the authors:

#1: Potential Measurement Error: This section of the paper was a highly technical consideration of the method used to measure energy expenditure. Suffice it to say that the method they used to measure calories burned per day may overestimate calories burned in the low-carb group. That, of course, would invalidate the major findings of the study. It is unlikely, but it is why the study needs to be repeated using a different measure of energy expenditure.

#2: Compliance: Although the participants were provided with all their meals, there was no way of being sure they ate them. There was also no way of knowing whether they may have eaten other foods in addition to the food they were provided. Again, this is unlikely, but cannot be eliminated from consideration.

#3: Generalizability: This is simply an acknowledgement that the greatest strength of this study is also its greatest weakness. The authors acknowledged that their study was conducted in such a tightly controlled manner it is difficult to translate their findings to the real world. For example:

  • Sugar and saturated fat were restricted and were at very similar levels in all 3 diets. In the real world, people consuming a high-carb diet are likely to consume more sugar than people in the other diet groups. Similarly, people consuming the low-carb diet are likely to consume more saturated fat than people in the other diet groups.
  • Weight was kept constant in the weight maintenance phase by constantly adjusting caloric intake. Unfortunately, this seldom happens in the real world. Most people gain weight once they go off their diet – and this is just as true with low-carb diets as with other diets.
  • The participants had access to dietitian-designed prepared meals 3 times a day for 5 months. This almost never happens in the real world. The authors said “…these results [their data] must be reconciled with the long-term weight loss trials relying on nutrition education and behavioral counseling that find only a small advantage for low carbohydrate compared with low fat diets according to several recent meta-analyses.” [I would add that in the real world, people do not even have access to nutritional education and behavioral modification.]

 

low carb diet and youWhat Does This Study Mean For You?

  • This study shows that under very tightly controlled conditions (dietitian-prepared meals, sugar and saturated fat limited to healthy levels, calories continually adjusted so that weight remains constant) a low-carb diet burns more calories per day than a moderate-carb or high-carb diet. These findings show that it is theoretically possible to increase your metabolic weight and successfully maintain a healthy weight on a low-carb diet. These are the headlines you probably saw. However, a careful reading of the study provides a much more nuanced viewpoint. For example, the fact that the study conditions were so tightly controlled makes it difficult to translate these findings to the real world.
  • In fact, the authors of the study acknowledged that multiple clinical studies show this almost never happens in the real world. These studies show that most people regain the weight they have lost on low-carb diets. More importantly, the rate of weight regain is virtually identical on low-carb and low-fat diets. Consequently, the authors of the current study concluded “…translation [of their results to the real world] requires exploration in future mechanistic oriented research.” Simply put, the authors are saying that more research is needed to provide a mechanistic explanation for this discrepancy before one can make recommendations that are relevant to weight loss and weight maintenance in the real world.
  • The authors also discussed the results of their study in light of a recent, well-designed 12-month study (CD Gardener et al, JAMA, 319: 667-669, 2018 ) that showed no difference in weight change between a healthy low-fat versus a healthy low-carbohydrate diet. That study also reported that the results were unaffected by insulin secretion at baseline. The authors of the current study noted that “…[in the previous study] participants were instructed to minimize or eliminate refined grains and added sugars and maximize intake of vegetables. Probably for this reason, the reported glycemic load [effect of the diet on blood sugar levels] of the low-fat diet was very low…and similar to [the low-carb diet].” In short, the authors of the current study were acknowledging that diets which focus on healthy, plant-based carbohydrates and eliminate sugar, refined grains, and processed foods may be as effective as low-carb diets for helping maintain a healthy weight.
  • This would also be consistent with previous studies showing that primarily plant-based, low-carb diets are more effective at maintaining a healthy weight and better health outcomes long-term than the typical American version of the low-fat diet, which is high in sugar and refined grains. In contrast, meat-based, low-carb diets are no more effective than the American version of the low-fat diet at preventing weight gain and poor health outcomes. I have covered these studies in detail in my book “Slaying The Food Myths.”

Consequently, the lead author of the most recent study has said: “The findings [of this study] do not impugn whole fruits, beans and other unprocessed carbohydrates. Rather, the study suggests that reducing foods with added sugar, flour, and other refined carbohydrates could help people maintain weight loss….” This is something we all can agree on, but strangely this is not reflected in the headlines you may have seen in the media.

The Bottom Line

 

  • A recent study compared the calories burned per day on a low-carb, moderate-carb, and high-carb diet. The study concluded that the low-carb diet burned significantly more calories per day than the other two diets and might be suitable for long-term weight control. If confirmed by subsequent studies, this would be the first real evidence that low-carb diets are superior for maintaining a healthy weight.
  • However, the study has some major limitations. For example, it used a methodology that may overestimate the benefits of a low-carb diet, and it was performed under tightly controlled conditions that can never be duplicated in the real world. As acknowledged by the authors, this study is also contradicted by multiple previous studies. Further studies will be required to confirm the results of this study and show how it can be applied in the real world.
  • In addition, the kind of carbohydrate in the diet is every bit as important as the amount of carbohydrate. The authors acknowledge that the differences seen in their study apply mainly to carbohydrates from sugar, refined grains, and processed foods. They advocate diets with low glycemic load (small effects on blood sugar and insulin levels) and acknowledge this can also be achieved by incorporating low-glycemic load, plant-based carbohydrates into your diet. This is something we all can agree on, but strangely this is not reflected in the headlines you may have seen in the media.
  • Finally, clinical studies report averages, but none of us are average. When you examine the data from the current study, it is evident that some participants burned more calories per hour on the high-carb diet than other participants did on the low carb diet. That reinforces the observation that some people lose weight more effectively on low-carb diets while others lose weight more effectively on low-fat diets. If you are someone who does better on a low-carb diet, the best available evidence suggests you will have better long-term health outcomes on a primarily plant-based, low-carb diet such as the low-carb version of the Mediterranean diet.

For more details read the article above.

 

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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