In recent years, the keto (ketogenic) diet has become increasingly popular. Like most fad diets, the enthusiastic claims have little substance aside from quick weight loss that is rarely sustainable. Of course, fast weight loss, with disregard for consequences is the common thread in every fad diet.
Fads are like mold on the bathroom wall. Once they take hold, they have a life of their own. Most fads seem to quickly gain celebrity endorsements along with numerous books that are long on opinions and short on credible evidence. It’s curious how so many glamorous stars can become experts about a new fad or, for that matter, churn out full-length books long before credible research has been conducted. Often the Keto diet books have little more to offer than “eat enough fat, and you will lose weight.” Short of at least one reference to a credible and applicable peer-reviewed research report, it’s remarkable that these books sell by the millions.
Recently, as measured by Google searches, the Keto diet has been a top search term about nutrition and dieting. As you might expect, people that sell diet information are quick to notice trends like this and in response, push more information into the marketplace. Soon enough rumors become facts in the minds of many. As the fad grows, food distributors catch the smell of profit and pile on with packaged “keto foods” that cleverly suggest a health benefit without actually making any specific claims.
Enthusiasm for a high-fat diet like the ketogenic diet was in part a response to what was believed to be a failure of low-fat diets. In practice, few ever ate a truly low-fat diet. Most in America followed a diet that’s was at least 30% fat. What has worked against most that tried to improve their diet by controlling fat intake was the increasing availability of convenience foods. The habit of eating these foods, especially refined carbohydrates, has increased the average daily consumption of calories over the last 50 years by almost 300 calories per day. This increase in calorie consumption is no surprise, given the increasingly addictive nature of engineered convenience foods.
Claims made for treating excess weight gain and type 2 diabetes with the ketogenic diet have also received quite a bit of attention. While some short term improvements have been reported, the claims made for the ketogenic diet greatly exceed the evidence supporting its use. Anecdotal stories of long term weight loss are the exception. As with all fad diets, a few will have exceptional willpower and could lose weight on any diet. Should you try the keto diet and have short term success losing weight or improving your A1C, you too have a shot at being a famous author since that appears to be the only credential required.
The Ketogenic diet differs somewhat from other low-carbohydrate diets (Paleo, Atkins, and South Beach, etc.). In particular, the Ketogenic diet recommends foregoing nearly all carbohydrates, usually avoiding excess protein, and consuming high levels of fat (typically exceeding 70% of calories). In the absence of carbohydrates that can be converted to glucose, the liver turns fat into ketones (a type of acid) and sends them into your bloodstream as an alternate source of energy. While this alternative source of energy is a good thing in the short run, making fat such a large part of the diet is not sustainable and definitely not healthy as a long term solution.
There are several variations of the Keto diet that are worth noting. For example, the standard ketogenic diet is 5% carbohydrate, 20% protein, and 75% fat. However, some variations recommend 90% fat. In contrast, a high protein keto diet might include 35% protein, 60% fat, and 5% carbs. Other variations of the keto diet allow cheat day to eat more carbohydrates. Finally, a plant-based ketogenic diet relies on high-fat plant foods such as nuts, seeds, avocados, coconut, and bottled oils. Regardless of the variation, there is no known human population eating a Keto diet of any type that experienced long lifespans or long healthspans. To the contrary, a recent study concluded that people who eat low-carb diets have shorter lifespans.
Analysis of over a dozen studies that all lasted beyond one year shows that on average, a ketogenic diet provides about two pounds more weight loss than a high carbohydrate diet. Although this is a very small difference, it is a nice result. The more important consideration is whether the ketogenic diet is sustainable and whether it supports long-term health.
As mentioned previously, the broad class of low carbohydrate diets that the ketogenic diet belongs to produce poor health outcomes. Furthermore, there is no evidence that the diet supports longevity or even short term cardiovascular health. To the contrary, staying on the keto diet for an extended period of time will result in a degradation of most biomarkers like cholesterol, triglycerides, and C reactive protein.
Be aware that some biomarkers observed in a blood test may initially improve while on an ultra low carbohydrate diet. In the short term, people on ketogenic diets with type 2 diabetes often show improvements in glucose levels and blood sugar stability. Unfortunately, this improvement depends on a nonsustainable diet.
Other downsides of the ketogenic diet include the ‘keto flu’, a malaise that can be accompanied by a period of fatigue, weakness, and gastrointestinal disturbances. Other problems that may arise include kidney stones, constipation, muscle cramps, headaches, diarrhea, pancreatitis, and halitosis. Worst case outcomes include bone fractures, cancer, restricted growth, and cardiac arrhythmias. Without supplements, vitamin and mineral deficiencies are likely.
The greatest risk of the ketogenic diet may be damage to the natural gut microbiome due to insufficient fiber. Without an abundance of vegetables, fruits, legumes, and whole grains in the diet, many of the aforementioned problems are not unexpected outcomes.
The risks posed by the ketogenic diet provides a compelling explanation for why all long-lived and healthy populations consumed enough carbohydrates to avoid chronic ketosis. In the Blue Zone communities where the longest-living populations exist, people, subsist on a diet that exceeds 50% carbohydrates from whole foods (beans/legumes, grains, vegetables, and fruits).
As a forewarning of what you may find in the typical keto diet book, I’ll share with you an example from the library’s new bookshelf. The book I picked up was “Keto Quickstart” by Diane Sanfilippo.
The first statement I had trouble with was on page 20, which proceeded to advise,”…we get some trivial amounts of protein from plant-based foods, especially legumes…” If this were true, there would be no animals on earth since the source of all protein is plants.
The second bit of advice (page 27) that left me wanting to scream was a recommendation of 90 grams of protein a day for men. The correct recommendation would have been 0.36 grams per pound of body weight or about 56g per day for the average sedentary male and 40-45 grams per day for a female. Recent research about the body’s ability to recycle protein suggests that even less protein may be even healthier for us. Importantly, know that aside from people with certain diseases, a case of protein deficiency is so rare that most doctors in America have never seen it.
As I proceeded, the book further stretched the limits of credibility as it advised that, “high cholesterol isn’t something to be concerned about.”
Usually, I would have already put this book away, but curiosity kept me reading. On page 49, the author tells us that animals are a better source of essential nutrients than plants. Well, that did it.
In appearance, the book was a work of fine publishing with charming formatting, excellent artwork, and a five-star rating on Amazon. The book even included references to credible studies. Unfortunately, decorating a book with references to prestigious studies does not enhance the book unless the author has enough knowledge to interpret the studies. Can you expect more from the many other keto advice books? Well, perhaps you can if you enjoy the genre I call diet fiction.
If looking for credible sources of nutrition advice, several excellent books can fill in the details. For recommendations, visit my blog at www.DocNeighbors.org and search on the term “diet.” If still unsure about how to proceed, then join me for a chat on Saturday mornings or schedule an appointment to discuss your needs.
Nancy Neighbors, MD