An overview of the ketogenic (or “keto”) diet. The first installment of the Diet and Fitness Profiles Series.
The ketogenic – or “keto” – diet is a low-carb, high-fat diet. Our bodies break down carbohydrates (carbs) by converting them into sugar, which we then use as energy. By slashing your carb intake, your body runs out of sugar and instead uses both dietary and stored body fat for energy. This metabolic state – where your body uses fat instead of carbs as its primary fuel – is called “ketosis.” With its emphasis on fat burning, the keto diet is a popular choice for weight-loss.
A purely keto diet – not to be confused with the Atkins diet, another low-carb diet – goes back to the 1920s and 30s, when it was used as a popular therapy for epileptic seizures. It fell out of fashion with the development of anti-seizure drugs and began to regain traction in the early 2010s.
The key to a successful keto diet is to stay in ketosis. On a keto diet, roughly 70 percent of daily calories come from fat; 20 percent come from protein; and 10 percent come from carbohydrates (carbohydrates typically make up at least 50 percent of the American diet.) You can adjust the ratio slightly depending on your needs.
So, what can you eat?
You should base the majority of your diet on fat-rich foods like:
Avoid eating carb-heavy foods, such as:
Even though most of your calories will come from one macro group, you can still have a variety of foods on a keto diet. In addition to fattier cuts of meat (including poultry, beef, lamb, and pork) and fish, you will also be eating dairy, cheeses and butters (milk is allowed in moderate amounts, but be sure to stick to whole-fat). And fruit and vegetables are still allowed, so long as you opt for low-carb choices.
At first glance, the keto diet seems too good to be true. Who knew that you can have your fill of meat, cheese, and butter while losing weight? And unlike most crash diets, the satiating fats allowed on keto leaves you feeling full and satisfied.
On the other hand, the diet requires that you decrease your intake of foods that are well-recognized as healthy, such as whole grains and sweet potatoes. You also have to avoid eating too much protein (which differentiates the keto diet from the Atkins diet). Others may have issues with eliminating alcohol from their lives.
Perhaps the most challenging aspect of the diet is ensuring that you stay in ketosis. Accidentally eating too many carbs or too little fat will throw you out of the fat-burning metabolic state. Some people may have trouble monitoring the chemistry of their metabolism accurately, at least not without medical intervention or tech (like using ketone strips).
While carb-rich staples like rice and pasta are cheap, you can still eat keto on a budget. Buy your meat, vegetables and berries frozen to save money. Fatty fish may be on the expensive side, so opt for canned if you need to.
The consensus on the efficacy of the keto diet is mixed.
One study published in he American Journal of Clinical Nutrition found that participants following a low-carb ketogenic diet (with, however, a slightly higher protein intake than most standard keto diets) lost more weight than those following a high-protein diet that allowed for moderate carb intake. Another study found that obese patients lost a significant amount of weight on a keto diet over the course of 24 weeks, without any adverse effects.
However, another study also published in the American Journal of Clinical Nutrition found that participants on a non-ketogenic diet had better moods, more energy, and lower levels of inflammatory markers than those following the keto diet. Study participants on both diets lost an equal amount of weight, but the researchers advised against going on the keto diet.
It’s also important to remember a standard rule of weight loss: calories in, calories out. This, in addition to cutting out unhealthy carbs and sugars from your diet – may be the real secret to shedding extra pounds.
“The key to weight loss is to burn more calories than you eat each day, no matter the source of those calories,” says Maria Petzel, a clinical dietician at MD Anderson. “Being in ketosis will suppress the appetite, and that may help to lower total calorie intake in general.”
As far as agreement among nutritionists and dietitians goes, the jury is still out. Some dietitians, including Kristen Mancinelli, MS and RD, are low-carb and keto enthusiasts. “Ketosis dramatically diminishes hunger—another boon to weight loss that’s unique to ketosis, so overconsumption tends not to be a problem.” she says.
Others are more skeptical. Andres Ayesta (MS, RD, LD, CSCS, CSSD), says that more research is needed. “Studying the ketogenic diet for a long time is more difficult than many diets because it’s more extreme,” he says. “I think the premise is there, but there’s more research that needs to be done. Time will tell.”
While the long-term effects of the keto diet are still unclear, medical research indicates that there may be some short-term benefits associated with following the diet.
“Based on the available literature, KD [keto diet] may be associated with some improvements in some cardiovascular risk factors, such as obesity, type 2 diabetes and HDL cholesterol levels, but these effects are usually limited in time….More studies are therefore warranted to better assess the effects of long term use of KD on metabolic diseases and cardiovascular risk factors, but also to better define which dietary macronutrient composition is optimal,” concluded a study published in Nutrients, a peer-reviewed journal on human nutrition.
Another study, published in the International Journal of Environmental Research and Public Health concluded that “A period of low carbohydrate ketogenic diet[ing] may help to control hunger and may improve fat oxidative metabolism and therefore reduce body weight.” However, the study did not track for long-term results, noting that “the duration of ketogenic diet may range from a minimum (to induce the physiological ketosis) of 2–3 weeks to a maximum (following a general precautionary principle) of many months (6–12 months).”
At least in the short-term, the keto diet is a reasonable choice for those wanting to lose weight without having to deal with hunger. However, since the diet has entered the mainstream only in the past few years, more research is needed to determine whether it is healthy and sustainable in the long-term. As always, consult your doctor before attempting any specialized diet.
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