Carbohydrates are traditionally known as the main source of energy for the body and organs. But there have been some newer trends like Whole 30, Atkins, and Ketogenic diets that significantly reduce the amount of carbohydrate that a person is allowed to ingest, replacing that carbohydrate with fat. In many cases these diets have led to weight reduction and improved blood glucose. Even still they are not diets approved or recommended by Doctors or Dietitians alike.
While fats are a welcome source of energy for most of the body, a few types of cells, such as brain cells, have special needs. These cells could easily run on glucose from the diet, but they can't run on fatty acids directly. So under low-carbohydrate conditions, like an extremely low carb diet or after prolonged fasting or exercise, brain cells require the body to make fat-like molecules called ketone bodies. This is why a very-low-carbohydrate diet is sometimes called "ketogenic." Ketone bodies are also related to a dangerous diabetic complication called ketoacidosis, which can occur if insulin levels are far too low. You could enter ketosis with as few as 20 grams or as much as 100 grams. The only way to really tell whether you’re in ketosis is to check via various testing methods (which each has its own problems with accuracy), urine test strips are the most common. Ketone bodies could alone provide enough energy for the parts of the body that can't metabolize fatty acids, but some tissues still require at least some glucose.
Glucose can be made in the liver and kidneys using protein from elsewhere in the body. If not enough protein is provided by the diet, the body starts breaking down muscle cells.
Clinically approved recommendations for daily carbohydrate intake is around 45-65% of calories from carbohydrate. On a 2000 calorie diet, that means between 225 and 325 grams of carbohydrate per day. Low carbohydrate diets typically tend to be limited to around 50-70grams carbohydrate per day.
These are usually 25-30g or less of carbohydrates per day, or around 5-6% of a 2000 calorie diet. In place of carbohydrates, the diet in turn becomes around 60-75% fat and 20-35% protein.
Potential benefits for certain types of epileptic conditions
If you want to know about ketogenic diets and the brain, look at the part of the brain known as the hippocampus- this part is responsible for learning and memory, but also a type of epilepsy called mesial temporal lobe epilepsy. There is some research to suggest a low carb diet helps treat epileptic seizures in the brain by breaking down mutated mitocholndrial DNA in the brain. One study suggests that among neurological disorders with mitochondrial dysfunction, patients should avoid a ketogenic diet because it may accelerate rather than reverse the neurodegenerative process. From this research, a ketogenic diet may act as a stressor (just as exercise would) with potentially beneficial effects on the brain which promotes the natural selection of healthy mitochondria, but in those individuals with mutated DNA, the diet requires further testing. Other research on neurological diseases like Alzheimers and Parkinson's disease suggests also a potential temporary benefit. The evidence is not clear enough to support use of the diet for those individuals, and more research is needed.
There aren't many longitudinal studies regarding people on keto diets for a long-term, but this one publication from Virta has research after 1-year of patients being on the program. There have been significant reductions in weight, and they decreased or discontinued some patients’ hypertension and diabetes oral medications on this diet after just one year. Part of the reason patients remain stable at the end of year one is simply because weight reduction is directly linked to improvements in blood pressure and diabetes. A lot safety issues need to be addressed in their long term trial, but I look forward to their 2-year data on these same subjects.
Improved short-term weight and glucose control
For many individuals, a ketogenic diet has been shown to improve their weight over time, thus improving glucose control. Also because the diet is extremely low carbohydrate, Diabetic patients see a significant improvement in average plasma glucose and A1C. For Diabetics, this seems like a dream come true, right?
Fatty Liver Disease and High Cholesterol
Although ketogenic diet intervention is effective in reducing body weight and controlling glucose homeostasis, it caused lipid metabolic disorders after just 6 weeks on the diet. Specifically, liver function tests, total cholesterol and free fatty acids in the blood rose, and rose more significantly in those with Diabetes. When combined with moderately intense cardiac exercise 5 days per week, however, these negative effects on the liver and cholesterol were muted.
Given the potential for increased use of dietary protein and protein from the muscles for energy, the breakdown of these proteins may potentially lead to increased work by the kidneys to excrete excess nitrogen. Those with renal insufficiency, as a result, may suffer more from a high fat diet, though a couple studies have shown that a ketogenic diet may actually reverse diabetic nephropathy.
Effects on Digestion, Heart Health, and Liver
Those individuals with gastroesophageal reflux (GERD), heartburn, or problems with inborn errors of fat metabolism should not be on this diet. Diabetic patients taking SGLT2 inhibitors (Canagliflozin/Invokana, Dapagliflozin/Farxiga, Empagliflozin/Jardiance, or Ertugliflozin/Steglatro) should also not be on this diet. The diet is also extremely difficult to digest, and since it can stress the liver and other aspects of fat metabolism, it is not recommended for people with a poor appetite, or those with fatty liver, cirrhosis, cardiomyopathy, or dyslipidemia (non-normal cholesterol levels).
Weight Loss Is NOT Guaranteed
So if you think that you can go on a high fat diet and actually reduce your body fat, you're only getting part of the research. A few studies show many groups of individuals, especially those with a systemic nervous system that isn't completely intact, or patients who (aside from diabetes) are not completely healthy, a ketogenic diet may not help at all. On the contrary, most subjects in this study showed similar or better ketosis buildup with a diet of lower fat content. These observations suggest that personalized monitoring, and regular blood work before and during diet initiation is necessary Also, patients with an already with lower fat percentage, BMI, as well as higher metabolic rate (REE) have higher ketone buildups, and thus already metabolize fat more efficiently and thus would see more of a benefit than those with a slower metabolism.
If You Insist on Trying Keto, Here's What You Gotta Know:
Not all fats are considered equal: a diet high in saturated fats (meat, cream, cheese, animal fats, palm oil, coconut, chocolate) is not recommended. A high fat diet that is especially rich in omega-3 rich fatty acids, nuts, seeds, seafood, avocado is less detrimental to the heart.
Non-starchy vegetables are key in maintaining a regular and healthful digestion and metabolism, and a generous serving should be consumed with each meal.
Supplementation of multivitamins and omega-3 fats is necessary.
When eating carbohydrates, make sure its healthy, high fiber, and whole grain to better supplement your body with more nutrients that it may be missing by not getting a balanced diet (a few examples: beans, lentils, barley, buckwheat, farro, freekeh, quinoa, etc...)
Exercise: Regular, moderately intense physical activity 5 days per week for 30-60 minutes is necessary to reduce the negative impact on liver and cholesterol levels.
Frequent monitoring of blood levels and symptoms, and regular check-ins with your doctor and dietitian are pertinent to seeing results with reduced impact of potentially negative side effects.
The Bottom Line
Ketogenic diets may not be harmful in some cases, but in those cases where it may be safe more research is still needed to see how effective it is in treatment of disease. With many common illnesses a ketogenic diet is not safe and should not be considered. It may help with glucose management and weight loss in some patients, but the patient should ask the doctor to review their blood results to make sure it is safe to start. After beginning a ketogenic diet the patient should be followed more closely with blood drawn more frequently throughout the process to make sure no adverse effects are shown. More research is needed on the amount of fat, protein and carbohydrate that is safe, as well as the safest duration of a keto-diet and how to transition out of one.
This article is still under construction, and as more adequate research is gathered, I'll be updating this post appropriately. Though in the past year I've had numerous patients and people desperate to eat junk and still lose weight asking about this diet, but since neither the FDA, ADA, AHA, nor AND have adequate position statements regarding this diet to point my patients toward, I had to develop something. Please always be cautious when beginning a new diet, and ask unbiased professionals for advice.