A Close Look at the Latest Diet Fad

The latest trend in the diet world is the “Carnivore Diet,” a movement that started gaining popularity a few years ago. The diet primarily consists of fatty meat, especially beef, followed by lamb, pork, chicken, and fish, and, optionally, eggs, butter, heavy whipping cream, and/or hard cheeses. Only water is consumed as a beverage (though plain tea and coffee are acceptable). No plant-based food is consumed while following this diet. There is no restriction on quantity of food; dieters are counseled to only eat when hungry and until full.1

Shawn Baker, a California-based body builder and former orthopedic surgeon (Baker’s medical license was revoked
in 2017), is perhaps the most well- known advocate of the all-meat diet.2–4 His book, The Carnivore Diet, which was released this past April, claims that “common diseases that are often thought to be lifelong and progressive are often reversed on this diet.”5  

Baker and his followers claim the Carnivore Diet offers the following benefits:6

• Relief from depression symptoms

• Elimination of joint pain • Increased energy
  • Decreased weight
  • Increased libido

Let’s take a close look at these claims and examine the supporting scientific evidence.

CLAIM: Relief from depressive symptoms

Testimonials are available on one
of Shawn Baker’s websites (www. meatheals.com) and elsewhere in which many followers of the Carnivore Diet credit the all-meat diet with eliminating or reducing feelings of depression.7,8
A study frequently cited by those who hail the all-meat diet’s antidepressant effects actually evaluated the effects of a ketogenic diet (see adjacent sidebar for definition), not an all-meat diet,
on depression in rats, not humans.9 However, in an article on the Healthline site,10 Jeff Volek, a professor at The Ohio State University (indicated by the author of the cited article as being an expert on the ketogenic diet), was quoted as saying there “might be some merit” to claims that a meat-oriented diet can improve symptoms of depression. According to Volek, “There is a growing body of
work that links excessive sugar intake to abnormal brain chemistry that manifests in different ways such as depression. Thus, by virtue of cutting back on sugar and processed carbs, a ketogenic diet
may improve mood state. The increase in circulating ketones may also directly benefit brain chemistry and function in ways that improve depression,” though, the article continues, this has yet to be demonstrated in large, controlled studies. One also might argue that reduction in symptoms of depression could, at least partially, be attributed to the weight loss: some research supports this11,12 while other research indicates that weight loss can actually induce depression.13 However, while a ketogenic diet theoretically might reduce symptoms of depression, there is no direct evidence supporting the claim that an all-meat diet will reduce symptoms of depression.

CLAIM Elimination of joint pain

We were unable to find any controlled studies assessing the
effects of an all-meat diet on joint
pain. However, a quick search on the United States National Library of Medicine’s Pubmed database (a life sciences and biomedical database of published research) did reveal many studies evaluating the effects of various lifestyle modifications, including diet, on symptoms of arthritis and other joint disorders.14 A 2015 prospective, randomized, open-label study seems fairly representative of most research on the topic, and appears to support the benefits of a balanced diet of fruits, vegetables, and lean meats for better management of arthritis symptoms.15 In this study, participants with osteoarthritis who consumed a plant- based diet experienced significantly greater improvement in energy/vitality and physical functioning measures, including joint pain, compared to those who consumed an omnivore diet.15 Thus, while diet modifications have been shown to improve joint pain, there is no evidence to date supporting the claim that an all-meat diet will improve joint pain. It should be noted that weight loss can also improve
joint pain;16 therefore, improvements
in joint pain while on an all-meat
diet could potentially be attributed,
at least in part, to weight loss, but linking the improvement directly to the consumption of a meat-only diet is not backed by science.

CLAIM Increased Energy

There are many studies supporting the positive effects of low- carbohydrate diets on multiple health outcomes, including weight loss, diabetes management, cholesterol levels, metabolic syndrome, and quality of life.17–19 Foods made from simple carbohydrates (refined sugars, white flour, white rice), which are not allowed on a ketogenic diet or an all-meat diet, are digested quickly and release immediate bursts of glucose (energy) into the bloodstream, which might make an individual feel very energetic for a very short period time, but then he or she will likely experience the infamous “sugar crash” a short time later as the glucose is quickly burned away.20 Research suggests that a low-carbohydrate diet might help one avoid sugar crashes by enabling the body to maintain a more steady state of energy.18 Additionally, a person with overweight or obesity who consistently consumes a ketogenic diet might experience a boost in energy due to the weight loss itself and/or due to improvement in other dysfunctions related to obesity.

Again, the reviewed studies all evaluated ketogenic diets, not an all-meat diet.17–20 While one might theorize that an all-meat diet could have a similar effect on energy, its direct impact on energy, endurance, and overall health has yet to be determined through science.

CLAIM Decreased Weight

In 2017, Kris Gunners did an excellent review of 23 randomized, controlled studies (the gold standard of research) comparing low-carb diets to low-fat diets, looking at factors like weight loss, cholesterol (total, LDL, HDL), triglycerides, and blood sugar levels. You can read the full report here https://www.healthline. com/nutrition/23-studies-on-low- carb-and-low-fat-diets.17 In summary, he found that among the 23 studies, the greatest amount of weight loss always occurred in the groups of people who consumed low-carb diets. In fact, individuals in the low-carb diet groups often lost 2 to 3 times more weight than those in the low-fat groups and, overall, had less abdominal fat. A highly restrictive diet, such as the Carnivore Diet, suggests there is potentially less risk of overeating (i.e., bingeing on steak seems unlikely). Additionally, an all-meat diet can trigger ketosis, which is a metabolic state often present in individuals with diabetes but can also be caused by a diet that is very low in carbohydrates. A very low-carbohydrate diet can cause you to have less glucose in your blood, which will, in turn, cause your body to burn fat for energy instead of sugars.18 Therefore, theoretically, an individual who consumes only proteins and fats would potentially lose weight. However, research specifically evaluating the effects that an all-meat diet has on weight loss in humans is lacking. Thus, while research supports the effectiveness of low-carb diets as tools for weight loss,17 the claim that an all-meat diet will result in weight reduction, while not unreasonable, remains unconfirmed in the science arena.

CLAIM Increased Libido

Researchers have reported greater improvements in erectile functioning among individuals who consumed high-protein, carbohydrate-reduced diets compared to individuals who consumed very low-calorie diets.21 Other researchers have reported improvements in erectile dysfunction among men who consumed the Mediterranean diet versus those who consumed Western, Paleo, or Vegetarian/ Vegan diets.22,23 Weight loss itself has been associated with improvements in sexual functioning as well.24 However, we were unable to find any quality evidence supporting the claim that consuming an all-meat diet will improve one’s libido.

CONCLUSION

The Carnivore Diet is a recent trend
in the weight loss arena in which the individual consumes a diet restricted to animal-based food sources only, primarily red meat. Plant-based foods are not considered part of the diet and are highly discouraged by its supporters. Proponents of the Carnivore Diet claim the all-meat diet will provide relief from symptoms of depression, eliminate joint pain, increase energy, decrease weight, and increase libido. The weight loss claim might be considered a reasonable one, primarily because the all-meat diet is highly likely to induce ketosis, in which the body burns fat for energy instead of sugars. Weight loss itself has been shown to improve joint pain, increase energy, and improve sexual functioning. Weight loss might also help improve symptoms of depression, though research is mixed on this. But we were unable to find any randomized, controlled studies specifically evaluating the effects an all-meat diet can have on humans, especially long-term. A low-carbohydrate diet, on the other hand, has been shown by several studies to have many positive effects on health, particularly weight loss.17–20 But low-carbohydrate diets, even those considered “high-protein,” still incorporate some plant-based food sources into the mix, such as non-starchy vegetables, nuts, and seeds. There is scientific evidence that frequent red meat consumption increases risk for diabetes, heart disease, and all-cause mortality.25–27 Additionally, numerous studies have demonstrated the health benefits of a balanced diet that includes a variety of unrefined carbohydrates, proteins, and fats, with an emphasis on vegetables, whole grains, and healthy oils—the Mediterranean Diet, for example, has been studied extensively and has been shown to have multiple positive effects on health.28

While weight loss can have a positive impact on health, there are many other factors that affect human health in the long term. There is no evidence that consuming an all-meat diet will directly confer any short-term or long-term health benefits other than the possibility of weight loss. There is counter-evidence, however, that frequent consumption of red meat increases one’s risk for diabetes, heart disease, and early death. Therefore, until we learn more about a meat-only diet through rigorous, long-term, human studies, it seems prudent to adhere to

a diet that has been backed by science
to provide health benefits, and to date, none of these evidence-based diets recommends restricting caloric intake
to animal-only food sources. Anyone considering any form of the Carnivore diet, particularly those at high risk for diabetes and heart disease, should consult with their physician first and openly discuss what this diet entails and how it might impact their health.

What is a ketogenic diet