Curious About the Keto Diet?

Clinical dietitian Mary Montgomery explains what you need to know about this almost-no-carb diet.

Assorted meats, nuts and cheeses
Assorted meats, nuts and cheeses

The ketogenic diet has gotten a lot of hype recently, but is it healthy? For those looking to shed a few pounds and keep them off, the ketogenic diet may be worth exploring.

Like the Atkins diet, the very-low-carb, high-fat ketogenic diet — or keto diet for short — boasts effective weight-loss results. But the keto diet is also proving to be beneficial for other medical conditions, including epilepsy, diabetes, Alzheimer’s disease, and even cancer.

Health Matters spoke with Mary Montgomery, MS, RD, CDN, a pediatric clinical dietitian at NewYork-Presbyterian/Weill Cornell Medical Center, to learn about what the diet entails, why it’s become so popular, and who might benefit from eating this way.

What is the ketogenic diet?
The ketogenic diet is a diet that is high in healthy fats, moderate in proteins, and low in carbohydrates. Eating this way puts the body into a metabolic state called ketosis, which burns fat for energy as opposed to burning carbohydrates.

There are several different versions of the keto diet; however, the “classic” or standard one — and the one backed by the most research — calls for a diet that is at least 75 percent fat, 20 percent protein, and 5 percent carbohydrates, and it requires weighing and measuring foods. (To keep this in perspective, carbohydrates normally account for approximately 50 percent of the typical American diet.)

Is there a difference between the keto diet and the Atkins (or low-carb) diet?
Yes, the original Atkins (low-carb) diet, developed in 1972 by Dr. Robert Atkins as a weight-loss therapy, does not limit protein, and foods are not weighed or measured as in the keto diet. As a result, ketosis may not be achieved due to excess protein intake.

What is ketosis and why is it effective in helping people lose weight?
Ketosis results from decreasing carbohydrate intake and increasing fat intake; this changes our metabolism from using glucose for energy to using fat. The body is then forced to burn stored fat for energy, accelerating weight loss.

A ketogenic diet, for those who want to lose weight, is typically part of a low-calorie way of eating. Additionally, the healthy fats that are being consumed as part of the diet provide a feeling of fullness, which results in less overeating.

What foods can you eat while on the keto diet?
Healthy fats — such as avocado and avocado oil, olive oil, and nuts and seeds — and some saturated fats — such as coconut oil, ghee, butter, and heavy whipping cream made from grass-fed cow’s milk — are all encouraged. Lean protein is allowed in specified amounts (too much protein can prevent ketosis). Poultry, lean beef, and cold-water fish (like salmon, herring, mackerel, and tuna) and other seafood are good protein sources. Of course, carbs are limited to dark green leafy vegetables, such as broccoli, spinach, and kale, as well as other low-carb veggies like cauliflower, peppers (red, yellow, and orange), asparagus, and zucchini. Berries are OK in small amounts.

Infographic depicting sample keto meals

What foods should you avoid?
Avoid simple sugars like sweetened beverages, juice, cakes, cookies, pasta, breads, cereals, and any carbohydrates that will trigger a rapid glucose increase. The good news is that once adapted to the diet, tastes change, and sweets are typically not desired.

There are many keto foods now on the market that can make life much easier, as well as dozens of websites with delicious keto recipes and meal ideas.

What are some health benefits of the keto diet? Any evidence or studies out there that prove it is beneficial?
The keto diet can decrease inflammation and reduce oxidative stress in the body. According to multiple studies, it is an effective treatment for some epilepsy disorders; since about 35 percent of people with epilepsy do not respond to medications, the keto diet provides another option for treatment of seizures. The diet is also effective at treating people with type 2 diabetes and is showing promise for improving other neurological conditions and metabolic disorders. It can prevent or reverse some chronic diseases, improve memory and cognition, and reduce body fat. There are also very early studies suggesting that combining a keto diet with chemotherapy during cancer treatment could even help stop tumor growth, but more research is needed.

Why is the keto diet recommended for people with diabetes or prediabetes?
Because the keto diet helps to reduce blood sugar and insulin levels, it is now being used for people with type 2 diabetes and for people with prediabetes to lower their hemoglobin A1C to a healthy level.

Who else can benefit from this diet?
Women with polycystic ovary syndrome who follow a low-glycemic-index diet — a variation of the keto diet that involves eating based on how foods affect your blood sugar level — have also seen positive results. Recent studies show the diet may treat the following alone or have compounding effects with other medical treatments: migraine headaches, brain tumor/cancer, Alzheimer’s, Parkinson’s disease, mitochondrial disease, Lou Gehrig’s disease (ALS), autism, and traumatic brain injury. Overall, more research is necessary.

For the general population, is the keto diet healthy?
While this diet has been shown to accelerate weight loss and to improve certain health conditions, it has its fair share of critics. Because the diet requires you to eat mostly fat and protein, it may prevent the body from getting all the vitamins and nutrients it needs on a daily basis.

Is there anyone who should not try this diet?
Anyone with a history of kidney stones, acute pancreatitis, and/or carnitine deficiency shouldn’t try the diet. A poorly formulated keto diet can contribute to the formation of kidney stones because the diet can be somewhat diuretic and may acidify the urine. It can also exacerbate acute pancreatitis. And carnitine is what carries fatty acids into the cells to process fat and provide energy — someone with a primary carnitine deficiency would not have adequate carnitine to process the large amount of fat required for the keto diet.

Portrait of Mary Montgomery, MS, RD, CDN

Mary Montgomery, MS, RD, CDN

Are there any negative side effects to be aware of?
Dehydration, electrolyte imbalance, metabolic acidosis, constipation, muscle cramping, vitamin and mineral deficiency, and an initial increase in both HDL (good) cholesterol and LDL (bad) cholesterol levels.

Maintaining proper electrolyte balance is important while following a keto diet. Depending on a person’s activity levels, it is recommended that 2 to 7 grams of salt be added to the diet daily. Many people add a cup of high-sodium broth twice a day to meet sodium needs.

Would you consider keto a long-term, sustainable diet?
A well-formulated ketogenic diet with adequate protein, proper supplements (such as a multivitamin, calcium with vitamin D, phosphorous, and levocarnitine), and regular labs would be sustainable. If people are curious and want to try the keto diet, I recommend working with a registered dietitian who understands what is necessary to successfully follow the diet and who can help monitor their health.

Mary Montgomery, MS, RD, CDN, is a pediatric clinical dietitian at the Epilepsy Center at NewYork-Presbyterian/Weill Cornell Medical Center. She specializes in the ketogenic diet for her pediatric patients suffering from epilepsy as well as for adults with epilepsy and cancer.

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