More and more people these days are trying out this diet with goals of quickly losing weight, stabilizing energy and mood, and getting those ripped abs everyone seems to be after. (4,8)
Ketogenic diets and other low-carbohydrate diets like Atkins and Paleo suggest eating only 50 grams of carbs per day, or as low as 4% of the diet as carbs. The rest of the diet consists of high amounts of fat and varying amounts of protein. (1,7) The more extreme ketogenic diets can be as high as 70-80% fat.
While the ketogenic will indeed help you lose weight and provide some short-term benefits, doing it long term comes with quite a few serious concerns.
10 Reasons to NOT Eat a Ketogenic Diet Long Term
Here are the top 10 risks that you should be aware of before attempting a ketogenic diet:
Increased Risk for Non-Alcoholic Fatty Liver Disease and Insulin Resistance
A ketogenic diet has been linked to the development of non-alcoholic fatty liver disease (NAFLD) and insulin resistance. (1)
Weight Loss, but Less Lean Mass
Studies show that after 12 weeks on a ketogenic diet, there was significant weight loss compared to grain-fed mice, but lean mass was significantly less.
Increased Risk for Respiratory and Colon Cancer
One study showed that men on a low-carb, high-protein diet saw an increased risk for respiratory and colon cancer. (10)
Increased Belly Fat
In mice fed a ketogenic diet, there was a 30% increase in visceral (belly) fat compared to chow-fed mice. (2) Both versions of a ketogenic diet were tested: high-protein, high-fat and high-fat, low-protein. (2) Overall, fat percentage increased after 5 weeks on a ketogenic diet compared to a grain-fed diet. This suggests that while weight loss may result, the body seems to store the excess fat as body fat in the same way eating excess carbs will. (1,3)
Reversal in Weight Loss
Long-term effects of a ketogenic diet actually showed a reversal in weight loss. During the first week, there was an initial decrease in weight, but after 18 weeks, the weight returned to baseline and started to increase gradually. (1,5)
Benefits Decrease Over Time
Once again, a ketogenic diet seems to offers numerous short-term benefits such as decreases in body weight, BMI, abdominal circumference, both systolic and diastolic blood pressure, triglycerides levels, fasting plasma glucose and HbA1c, an increase in HDL cholesterol levels and no change in LDL cholesterol levels. However, the authors of these three meta-analysis studies suggested a possible duration effect, where benefits seem to decrease over time. (1)
Increased Risk of Arterial Stiffness
Arterial stiffness is increased in children and young adults treated with the ketogenic diet. Arterial stiffness is an early marker of cardiovascular risk. (6) Arteries returned to normal after 1-2 years with dietary therapy.
Side Effects in Children with Neurological Concerns
Studies show children treated with a ketogenic diet for neurological concerns experienced a range of side effects including, constipation, hypoglycemia, and gastroesophageal reflux, kidney stones, growth disturbance, and acidosis. (6)
Increased Cardiovascular Risk
Studies done on low-carb, high-protein, high-fat diets are linked to increased cardiovascular risk. (10) While the ketogenic diet does show some lipid profile benefits, cholesterol and LDL levels were found to rise in most studies. (6)
The Arctic Gene
Finally, the only culture that came close to eating a ketogenic diet were the Inuit people of the Arctic, who had a naturally-occurring, very high-fat, low-carb diet of mostly seal blubber and fish meat. They actually acquired a gene to block them from going into ketogenesis from their super high-fat diet. (9) The question begging to be asked here is, why would the only culture who naturally ate a ketogenic diet acquire a gene to prevent ketogenesis if the ketogenic diet was, in fact, a health-promoting diet?
Eating a ketogenic diet is a version of a starvation diet where carbohydrates are dramatically restricted and the body is forced to burn fat as fuel.
In nature, this happens every spring and, in an evolutionary sense, it is what should all be doing each spring.
However, the ketogenesis of spring is not driven by a high-fat diet, but by severe calorie restriction and a low-fat diet.
The studies suggest that there are definite short-term benefits of a high-fat ketogenic diet. However, the long-term studies, which are just beginning to be published, are suggesting that this is a short-term strategy at best, and the risks and reversal of benefits start to surface after eating ketogenically for an extended period of time.