All About the Keto Diet

What do Kourtney Kardashian, Halle Berry and LeBron James have in common? They are all reported fans of the keto diet as a tool to maintain a healthy weight and lifestyle. As we think about improving our health, eating habits ranks near the top of the list. You’ve probably heard about the keto diet, which has been all over the news and continues to gain popularity as a tool for weight loss. But is it healthy and can it help you lose weight?

What is the keto diet?

The keto diet, which has been used for over a century as a treatment for patients with epilepsy, is focused on consuming fats such as butter, eggs, cheese, meat, fish and nuts with limited intake of carbohydrates. It's very similar to the Atkins diet, but the proportion of fats, protein and carbohydrates is fixed.

There are multiple variations of the keto diet, but in general more than 70% of your calories should be from fats, and less than 10% of your calories should be from net carbohydrates (approximately <30 grams net carbohydrates daily). The theory behind the diet is that it shifts your metabolism to burn fats rather than carbohydrates, and the byproducts of fat metabolism are called ketones. Ketosis is defined as a state where your body and brain are using ketones as fuel rather than carbohydrates.

What Are the Benefits?

Besides helping patients with epilepsy, there is growing evidence in the medical literature that a low-carbohydrate, ketogenic diet can help reduce glucose levels and insulin levels in patients with or without diabetes. Weight loss on the diet tends to occur quickly, which can be satisfying. You may notice reduced cravings, less hunger, and less symptoms from fluctuations in glucose, due to decreased intake of processed high carbohydrates foods.

The diet is also relatively simple to follow, and clear-cut in terms of what you can and cannot eat. There are ongoing studies to assess potential long-term benefits in patients with diabetes, obesity, neurologic disorders such as Alzheimer’s, Parkinson’s disease, headache, as well as cancer.

What Are the Challenges?

Some people starting on a keto diet may feel fatigue, stomach upset, constipation and muscle aches as their body attains ketosis, also known as ‘keto flu’. A change in the smell of your breath can also occur as the body breaks down ketones and produces acetone. Studies suggest that cholesterol levels do rise, in particular LDL and triglycerides, which can increase the risk of heart disease. Other concerns are that by limiting intake of fruits and vegetables, which are considered high in carbohydrates, one can develop deficiency of particular nutrients and vitamins which are crucial for overall health. If you have certain food allergies or prefer a vegetarian or plant-based diet, it may also be challenging for you to attain ketosis since most plant-based proteins may have some small amounts of carbohydrate.

Long term, it may be difficult to sustain such a restrictive diet focused on fats and proteins, as the human body has been developed to burn carbohydrates. Many on the keto diet describe how the cravings slowly return and can be hard to manage without family/social/medical support. If one chooses to add back carbohydrates into their diet, some of the initial weight loss will return and this can sometimes spiral out of control quickly without appropriate support. In addition, if you have a history of heart disease, stroke or diabetes, you should speak with your doctor before considering the keto diet and weigh the risks/benefits. In particular, diabetes medications may need to be reduced/adjusted as glucose levels improve.

The Bottom Line

The keto diet is simple, straightforward and can contribute to rapid weight loss, which make it a popular diet to consider as we strive to improve our health. However, you may experience some initial unpleasant side effects, and it may be challenging to maintain such a strict intake of fats and protein long term.

While short term use of the keto diet can jump start your weight loss journey, in the long run a program that allows carbohydrates in moderation in the form of whole grains with limited processed foods, as well as a diversity of fruits and vegetables as part of a balanced diet, may be more beneficial and more sustainable.

If you are looking to start your weight loss journey, consider speaking with a nutritionist and weight loss specialist to assist you in creating a personalized meal plan that fits you.

Reshmi Srinath, M.D. is an Assistant Professor of Medicine (Endocrine, Diabetes and Bone Disease) and Director of Weight and Metabolism Management Program for the Mount Sinai Health System