As spring hovers on the horizon, Jacksonites start to think about spring break. That means getting in shape for beach vacations, diving trips and biking or hiking adventures to the Southwest.
Cleanses and other diets seem to be advertised by local clubs this time of year. Locals are thinking of not just getting in shape but wearing much less clothing.
When I have nutrition conversations around town, the keto diet often seems to come up as the assumed healthiest way to eat. Even high level athletes seem to think they should be eating “keto” for optimal sports performance.
But is it the best way to eat? Let us explore the science.
A true classic ketogenic diet has been used since the 1920s for controlling some types of seizure disorders. And it works. As a dietitian, I have designed eating plans that are over 80% fat to control intractable seizures. Allowing patients to eliminate their medications for even a short period of time can be healthful and allow a person with these types of diagnoses to be much more alert and focused rather than drugged. It gives the body and brain a drug holiday.
More recently, “eating keto” seems to describe an eating plan that limits carbs like fruits, vegetables, grains, beans and sugar. It is generally loaded with fat, along with some protein and nonstarchy vegetables. A few fruits, in small quantities, like berries, are sometimes allowed.
The goal of this type of diet is to force the body into using a different type of fuel. Instead of relying on carbohydrates, the body uses ketone bodies, a fuel the liver produces from fats.
That seems simple enough, since the goal is often to use up extra body fat. However it is tricky to get the body to do that, and most keto dieters are probably not in ketosis, but simply losing weight by cutting down on calories. Cutting out whole food groups will cut down on calories. Unfortunately, it also cuts out many essential nutrients.
This diet does not seem to discriminate between healthy fats, like avocados, nuts and fish oils; and unhealthy ones like meat fat, butter, ghee and coconut oil. According to Harvard University dietitian Kathy McManus, saturated fat should be kept under 7% of daily calories to avoid stress on the heart and brain. Yet the keto diet is associated with a rise in LDL or bad cholesterol. In fact, I have seen huge rises in bad cholesterol in my patients who have tried this type of diet — up to a 100-point increase.
There are many other health risks associated with this diet. Over the past few years I have seen a dramatic uptick in cases of diseases of the gallbladder, kidneys and liver in young people who would not be expected to have these health problems. Most have followed a keto diet for a time. Some have had to have gallbladder surgery or kidney stone removal. Gout, a disease common to eating rich foods, seems to also be associated with this diet. And run-of-the mill health problems, like bad breath, constipation and fuzzy thinking are also side effects of this type of eating.
Quick weight loss can be achieved from this diet, but it is often simply the loss of carbohydrate storage, and the attached water molecules. Usually the first seven of 10 pounds lost is mostly these non-fat pounds. In fact, this type of diet seems to produce the least amount of fat loss compared to other macronutrient programs.
And about athletic performance? Yes, the body can adjust to using fat as a fuel, if it absolutely needs to. But there is a cost. The cost is oxygen. It has been known for many decades that for sprint activities, like mountain biking, short distance running and alpine skiing, carbohydrates are the best fuel. Keto diets tend to cause a higher perceived exertion in these athletes, along with poorer performance.
But it was thought that for steady state, endurance exercise, maybe a fat-based diet would be better. Yet according to the most recent study, the Supernova project, the body can adapt to fat use if it has to, but it is not optimal for ultra-distance high-intensity exercise. Optimal is the key term. According to sports scientist Louise Burke, chief of nutrition strategy at the Australian Institute of Sport, having a supply of carbohydrate before, during and after intense exercise primes the muscles’ pathway to the “top gear that wins so many endurance events.”
In the study distance racing athletes performed poorer on the keto diet than on a carbohydrate-rich eating plan. Race times were faster when athletes primed with carbs. And interestingly, the carbs also helped produce more nitric oxide, while the keto diet knocked out production of this important chemical. NO improves athletic performance by improving oxygen delivery to the muscles, increasing energy uptake, muscle velocity, power output and muscle growth. (Enough said, although expect a follow up article about NO.)
The bottom line: Short-term diets are not what I recommend in my nutrition counseling practice. Rather, adapting a long-term healthy eating plan that can produce permanent healthy outcomes is best. It is based on science, not the latest fad.
I recommend turning to sites like Stanford, UCLA and Harvard to find the best recommendations for your healthy eating. Or call your local dietitian nutritionist who can parse the difference between fact and fad. An individualized program based on your lifestyle and favorite foods will optimize your chance of success in health, sports performance and good living in our great outdoors.