My husband hacked my Amazon account recently to order an obscene number of cookies. The cookies are apparently nutritious, delicious, and keto... his latest dietary fixation. In our many years of marriage he's undertaken every food regimen from gluten-free to starvation, though my all-time favorite was the Prison Diet: canned food only, and only 3 cans a day. Ironically, my husband doesn't know what keto means, but he sees his lean, millennial co-workers eating keto diets and he wants to be lean (and young) too. Especially as a major birthday, which in number shall not be named, looms.
Keto diets, keto-friendly foods, KETO labels. It's all the rage. But what is keto and is it healthy?
Keto is short for the word ketogenic, which in dietary terms refers to any food that promotes ketogenesis in the body, or the production of a set of chemicals called ketones. Ketogenic foods are extremely low in digestible carbohydrates, either naturally or by design, thereby limiting the amount of carbohydrates available to our bodies for fuel. How does this promote weight loss? First we must understand the dietary nutrients our bodies rely on for energy and how they are used.
Carbohydrates are one of two primary energy sources for our body; the second is fat. We consume carbohydrates through our diet and regardless of type (starch, fructose, sucrose, mannose, etc.), almost all digestible carbohydrates are converted to a single sugar called glucose. Glucose enters our blood stream through the digestive system and directly supplies our tissues with needed energy. On the occasion that carbohydrate consumption exceeds our body's immediate glucose need (think fettuccini and French bread), then excess glucose is stored in our liver as glycogen. Later, at times of low carbohydrate intake, like between meals or while we sleep, glycogen readily mobilizes back into blood glucose in order to maintain healthy blood glucose levels and to fuel our tissues.
Glucose shares the role of cellular fuel with another important nutrient, fat. Depending on the organ or tissue, these two molecules are differentially used in our body. The heart, for example, relies almost entirely on fat metabolism to beat at a strong, steady rate, while skeletal muscle uses a combination of both glucose and fat, as determined by the strength and duration of its contractions. In contrast, the brain and its neural network solely rely on glucose for energy; the reason is because fats cannot cross the blood-brain barrier owing to their size and chemical nature. In fact, over sixty percent of our body's daily glucose utilization goes directly to fuel our brain.
So how do ketones fit into this picture? Ketones are evolution's effort to minimize our risk of starving to death, literally. They are a back-up fuel, produced and utilized by our tissues only in the absence of glucose, which is restricted during periods of fasting, dieting, and starvation.
Though ketones date back to earth's earliest life forms, humans are fairly unique in their ability to produce and use ketones for energy within the animal kingdom. In fact, it is only because our primate ancestors evolved the ability to make ketones (about 2 to 3 million years ago) that modern day Homo sapiens, and in particular our development of language and cognition, came to be. It is widely acknowledged by the scientific community that man's evolution, occurring over millennia, would not have happened without the support of ketones during the common famines that man faced; whether due to natural catastrophes or by man himself during hostilities and migrations. Ketones enable a starving man to survive 2 to 3 months as opposed to just several weeks.
This is because while our brain generally relies on glucose for 100% of its energy and cannot use fat, it can use ketones. This works by the following: when glucose is absent, stored fat is released from human adipose tissue and travels to the liver where it undergoes ketogenesis and is converted into ketones. The ketones then enter our blood stream and travel to the brain, as well as tissues like the heart, kidneys, and skeletal muscle, to be used as fuel. Once dietary carbohydrates are reintroduced, ketone production halts and our tissues resume their use of glucose. Ketogenesis is similarly induced by caloric restriction and fasting, both of which also limit glucose availability.
Different degrees of ketosis, or levels of accumulated blood ketones, are achieved depending on the time and extent to which carbohydrates are restricted as well as a person's caloric requirement. A person whose diet is rich in carbohydrates produces low ketones, less than 0.1 millimoles per liter (mmol/L) of blood. After a 24 hour fast this number increases 10 fold to 1 mmol/L. Three to seven days of fasting yields about 4 mmol/L while two weeks without food, essentially starvation, generates upwards of 8 mmol/L. Nutritional ketosis, induced through a ketogenic diet, aims for approximately 1 to 3 mmol/L ketones in blood. It should be noted that blood ketones in excess of 14 mmol/L is a pathological condition that is life threatening. Though it rarely occurs from diet alone, it can result from prolonged starvation and is most common in untreated diabetics whose ability to utilize blood glucose is severely compromised.
So is your brain better on ketones?
Some might argue, yes.
There are, in fact, two reasons why people keto: 1) weight loss and 2) cognitive benefits.
First, whether you keto or not, consuming a diet that is low in carbohydrates (including Atkins, Whole 30, etc.) will promote weight loss and in particular fat metabolism. This is because by limiting carbohydrate intake, you force your body to deplete its stored glucose and turn to stored fat for energy. As your body consumes its own mass, you will lose weight and inches. The difference between keto and other low-carb diets is the degree to which carbohydrates are restricted: keto is the strictest, allowing only 20 to 35 grams of digestible carbohydrates a day while other diets encourage 50 to 100 grams daily. For reference, the Institute of Medicine recommends 45 to 65% of a person's calories come from carbohydrates, which is equivalent to 125 to 180 grams per day for an average adult.
As it turns out, ketones have a unique and well-documented neuroprotective effect on the brain outside of energy production. The ketogenic diet is clinically effectively in the treatment of symptoms associated with epilepsy, autism, Parkinson's disease, Alzheimer's disease, and in traumatic brain injury caused from stroke and brain tumors. Science shows us that ketones directly alter gene expression patterns, and though the mechanisms of protection are not well understood, these molecules play an important role in lessening oxidative stress and inflammation in the brain and increasing the health of energy production. Anecdotally, heathy individuals who successfully maintain a ketogenic diet site a "mental clarity" that they've never before experienced!
But maintaining a keto diet and metabolic ketosis is no easy feat.
First, restricting digestible carbohydrates to 20 to 35 grams per day requires a lot of diligence and self-control (a limited taste palette helps, too). Most natural foods, including many fruits and vegetables, contain more carbs than this in a single serving. One banana, for example, has 35 grams of sugar - your daily allowance. Keto friendly foods, therefore, are exclusively high protein meats like chicken, beef, and fish, nuts and seeds that are naturally low in carbs and high in fat, high fat, low sugar dairy like cheese, cottage cheese, cream, and plain Greek yogurt, non-starchy vegetables like kale and spinach, and butter and oils. Some fruits, like berries and avocados, are allowed in moderation as their carbs come mostly in the form of fiber, which is non-digestible and therefore does not contribute to the overall glucose pool. But say farewell to all grains, grain-products, many fruits and veggies, and anything naturally sweetened.
Another major obstacle to this diet is that ketosis is fairly unpleasant - at least initially. Many people describe flu-like symptoms in the first two weeks of the diet, referred to as "keto flu": nausea, vomiting, headache, dizziness, and fatigue. Other symptoms may include sleeplessness, constipation, and muscle cramping. My one unwitting run-in with ketosis was debilitating enough to keep me away from the keto diet... after a 24 hour liquid cleanse (think cucumber juice) I awoke with the worst migraine of my life and dry heaved over the toilet for twenty minutes. It was an easy decision to forgo the remainder of the cleanse. Instead, I made a beeline for the Tropicana orange juice and within seconds of taking down the sugar, I felt human again. Even for those who can muscle through the flu-like period, the diet is so restrictive that most people are unable to maintain it for long periods of time, so it's not considered an effective weight-loss strategy for most.
A third knock on this diet is that there are no cheat days - not if you want to maintain metabolic ketosis and reap the cognitive benefits of ketones. As soon as you indulge in that glass of wine, piece of birthday cake, potato, or whatever your carb fixation is, you reset your body's glycogen levels and the ketogenic clock starts from scratch.
So returning to those KETO cookies. Ketogenic diets have traditionally relied on natural, low-carbohydrate containing foods, but the diet has gained so much momentum in recent years that companies are eager to engineer food products to meet keto requirements. Keto cookies are just the start. Other brands offer up powders, bars, and gel capsules, most of which contain lyophilized (dehydrated) fats, protein, and non-digestible sweeteners. Products that do contain natural ingredients rely heavily on nuts, eggs, and vegetable based oils or animal fat. The KETO cookies are no exception. The primary ingredients are almond flour (ground almonds), erythritol (a non-digestible sweetener), butter, more butter, whole eggs, tapioca syrup (a second non-digestible sweetener), and cream. The cookies, which are quite large, contain only 1 gram of digestible carbohydrates even though they are incredibly sweet, too sweet for me.
So my verdict on these cookies: if you are actually trying to go days, weeks, or months on end eating 35 grams or less of carbohydrates per day, then by all means, indulge in a KETO cookie. The ingredients are fairly whole and natural, outside of the sweetening agents. I imagine having a cookie like this can be a useful supplement for curbing the food cravings that come with a diet as restrictive as this. But for keto novices, like my husband, you should know that buying KETO cookies does not make for a keto diet, nor is it your gateway to metabolic ketosis.
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