Don't lie. When you first heard of the "caveman diet", you scoffed didn't you? Or perhaps you grunted a little. Sure sounded like another fad diet. I personally would've named it Encino Diet with Brendan Fraisier as posterboy to make it more competitive with Atkins, but hey caveman marketing is a bit primitive.

Fortunately for us, this doesn't appear to be a scam. Many patients with autoimmune or autoimmune-like conditions seem to benefit by changing to a diet based on evolutionary principles. No doubt you've heard of some of the most popular ones: Paleo, Primal, Specific Carbohydrate Diet (SCD), GAPS. There are a ton of resources out there on each diet, so I'll focus on the main differences between these 4 most popular diets & delve into success metrics, where available, rather than the details of each diet.

Hey McFly I'm borrowing the DeLorean to take a closer look at these dietary blasts from the past:

By far the most popular one, led by Loren Cordain & Robb Wolf. The focus is on all-natural (i.e. grass fed) animal fats and natural fats (ghee, avocado etc), and low carbs (starchy root vegetables, white rice, and other starches without antinutrients.) The basic tenet is that we're simply not evolved to optimize digestion and absorption of agricultural products.

There are no controlled studies on this diet yet, but lots of >90% success rates reported by various doctors internationally. Dr. Jean Seignalet in France conducted a trial on autoimmune patients, with success being defined as 50% reduction in symptoms, and here are the results:

Rheumatoid arthritis: 200 (sample size), 80% (success rate)

Lupus: 13, 100%

Mark Sisson is the main proponent. Basically the same as Paleo except it allows full-fat dairy. According to Mark's pictures, shirts should also be avoided. Wouldn't mind having that body though!

Chris Kresser is another big proponent of Paleo that has incorporated dairy such as grass-fed butter and kefir into his protocol with much success. He talks about not tolerating more than a teaspoon of kefir at first, but slowly building up to pints a day. I've heard similar stories from ME/CFS patients that benefit from fermented dairy. His theory is that taking probiotics via kefir actually changes your microbiota or gut flora to allow your gut to tolerate dairy.

I couldn't track down any statistics specific to the Primal Diet, but due to its similarity to Paleo I would imagine if you could tolerate dairy, the statistics for Paleo might be a good reference. 

This was developed by Sydney Valentine Haas, MD. At first glance it sounds like a low-carb diet, but the basic tenet is actually that carbs feed overgrowth of yeast & bacteria in the gut, so limit both the amount & types of carbs to well-absorbed. The major difference from Paleo: properly-prepared legumes such as beans are allowed, and like Primal, dairy is allowed.

Autism Research Institute's survey found that with 71% of parents noted improvement in their kids from SCD.

"Proponents of the diet claim there is an 80% recovery rate for Crohn's disease and a 95% recovery rate for diverticulitis." -

And most impressive, results of a pilot study done on Irritable Bowel Syndrome:

"Notably, 9 out of 11 patients were able to be managed without anti-TNF therapy, and 100% of the patients had their symptoms reduced." -

Based on the SCD diet, and developed by Dr. Natasha Campbell-McBride. The main difference from the other diets is the focus on

the gut, as opposed to just feeding it foods that are optimally digested & absorbed. Main difference from SCD: emphasis on bone broth and fermented foods, less beans, gradual implementation of dairy casein to tolerance starting from Ghee (which has virtually no lactose).

Because this diet's the newest of the list, statistics are lacking so far. In my personal opinion, based on what we know about leaky gut though, the use of bone broths to provide easily-absorbed nutrition and

the gut en route to building tolerance of fermented products makes this diet especially appealing for severe LGS.

There is far more similarity within these diets than there is different. GAPS was mostly developed as an improvement to SCD, and Primal was mostly developed as an improvement to Paleo. In the end, many practitioners agree that ultimately an elimination diet where you eliminate a food for 30 days and then add one thing in at a time (and monitor how you feel) is the way to figure out which foods and amounts of those food your body reacts to.

Is it healthy? On a low carb diet, you can lose weight consistently, lower your insulin levels, lower cholesterol, lower blood pressure, and stabilize your blood sugar (great for diabetics). “What about fruits and vegetables”, you ask? Since you’ll be eating less of these, it’s important to take a inside look on the side effects to have a low carb – or no carb – diet…
The key message these Low Carb Diets conveys is that carbohydrates promote insulin production, which in turn results in weight gain. Therefore by reducing carbohydrate intake, we will lose weight.
The truth is: by eating a Low Carb diet, you do not provide sufficient carbohydrates to your body for daily function. Therefore it will start burning the stored carbohydrates (glycogen) for energy. When your body starts burning glycogen, water is released. Therefore the drastic initial drop of weight at the beginning is only water you lose as a result of burning glycogen.
Some Low Carb diets are indeed high in fat! Some of these diets promise that you may eat as much meat, butter and cream as you want. There is no way for someone to eat that much fatty food and justify that it is healthy to do so! Numerous well-proven scientific research showed that diets high in fat and saturated fat can increase the risk of heart disease.
In addition, some Low Carb diets such as the Atkins Diet lump all carbohydrate foods together and give it a bad name. For example, the Atkins diet limits carbohydrate intake to just 20g daily at the beginning (vs 130g recommended level by the National Academy of Sciences’ Institute of Medicine). Most grains, fruits, beans, potatoes, rice, pastas, some vegetables are all excluded from this diet. Fruits and Vegetables especially, are rich in fiber as well as antioxidants such as Vitamin C, carotenoids, flavonoids, etc which are essential in the prevention of heart disease and cancer.
The truth is – in addition to losing water drastically at the beginning, these low-carb diets are often calorie-restricted!!! Followers only eat an average of 1000 – 1400 calories daily; compared to an average intake of 1800 – 2200 calories. To lose 1 lb a week, you only need to eat 500 fewer calories per day than you metabolize. Therefore, it doesn’t matter if you eat a high or low carb diet, you will lose weight if you restrict your calories to less than you need. One easy way to lose 500 calories a day without restricting food? Physical exercise. Speak to your registered dietitian – they are able to calculate how much calories you minimally need per day.
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Low Carb Diet – Does it Really Work?