Can the ketogenic diet miraculously help you lose weight? Cure diabetes? Preserve memory and brain health?
Some people say so. And while I certainly won't discount that it can be helpful, it’s considered a “medical diet” that can be risky under certain circumstances.
If you have a friend or relative who has tried (and raved) about the ketogenic diet recently, you may be thinking about trying it yourself. If you’re considering giving it a go, here’s what you need to know about the keto guidelines and how to decide if the keto diet is right for you.
What is the ketogenic diet?
Unlike popular diets that focus on the amount of protein or carbs you eat, the ketogenic diet focuses on fat. It’s considered a very restrictive diet (because, well, it doesn’t include an entire food group!) that’s very low in carbs and high in fat. Protein is in the middle territory, but it isn’t a high protein diet—it’s a high fat diet.
While fat had been unfairly suggested as a cause of obesity and contributor to heart disease, diabetes, and cancer, new research in both people and animals suggests that fat isn’t public enemy number one. The type of fat you eat matters and looking at fat in isolation isn’t helpful. Instead, we have to look at fat in the context of what else you’re eating, and in the case of the keto diet, eating a high-fat diet has been shown to help some people achieve weight loss pretty quickly (but keep reading before you dive into it).
How ketosis works
Simply put, the idea behind the ketogenic diet is to switch your body’s preferred fuel source to a backup fuel source. Normally your body uses glucose (from the breakdown of carbohydrate) as its main fuel. Carbs include both sugars and starches from foods, like cakes and breads, as well as many nutritious foods such as fruits, vegetables, pulses (beans and legumes), milk and yogurt, and whole grains. Glucose is the primary source of energy for your tissues and organs, like your brain and muscles. But, because your brain is so important to your survival, humans evolved to live through periods of fasting, which gives you a “backup” system to make sure your brain can still have the energy to help you survive under those conditions. Ketones provide that backup energy source.
Your body produces ketones from fat when food is scarce. Your brain, heart, muscles, and kidneys can use ketones for fuel when you aren’t eating a sufficient supply of carbohydrates. It’s a survival mechanism that switches your metabolism from a glucose-based fuel system to a ketone-based one. That ketone-based metabolic state is called “nutritional ketosis.” (Your body is so cool—it knows how to go through 100s of adaptations to use an alternative source of fuel!!)
With the keto diet, instead of fasting, you severely reduce the carbs you eat (goodbye bagels, pasta, and French fries) and up your fat intake in order to revert to the backup fuel system without going into starvation mode. (Speaking of fasting, if you’re curious about intermittent fasting, see my recent blog post to determine if intermittent fasting is right for you.)
When you shift into ketosis, it’s possible to lose up to 10 lbs in two weeks (some may lose more; others less), but keep in mind that much of that initial weight loss is due to water loss. (Geeky fact: the storage form of carbohydrate in your body hangs on to water, so depleting those stores results in water loss and therefore, weight loss.)
How to shift into ketosis
In order to manipulate your metabolism to shift into ketosis, you need to dramatically cut down on the amount of carbohydrates you consume and focus on getting most of your daily calories from fat.
The approximate macronutrient combinations for a ketogenic diet are:
55-65% fat30-35% protein5-10% carbohydrates (up to 50 g per day)
For the sake of an example, for the average woman who needs around 1,600 calories per day, that adds up to only 20-40 grams of carbohydrates per day. To put this into perspective, one medium-sized banana has 27 grams of carbohydrates. But carbs slip into your diet in other ways. For example, a typical serving of almonds supplies about 6 grams of carbohydrates and a cup of broccoli provides nearly 5 grams of carbs, so it’s easy to see how you’d go through your carb allowance very quickly!
Comparing the keto guidelines to my recommended macro pattern
Also, consider the macronutrient profile of the keto diet to the pattern I typically recommend for sustainable and long-term health and weight management. Here are the ranges:
25-35% fat25-30% protein45-50% carbohydrates
These ranges provide more flexibility, ensure you can enjoy a range and variety of foods (and therefore, the nutrients these foods supply), and have been linked to long term health and weight benefits through studies on eating patterns, like the Mediterranean diet and a flexitarian diet. (Curious about how many calories you need in a day? You can read my take here.)
The ketogenic diet and your health
Some studies show that a well-formulated ketogenic diet can help people who want to lose weight, or who have metabolic syndrome, insulin resistance, and type 2 diabetes. Following the keto guidelines may help with blood sugar control because there are fewer carbohydrates in the diet and this also helps improve insulin sensitivity. Strictly following the keto guidelines can also produce benefits to your cholesterol levels.
However, there’s a fine line between following the ketogenic guidelines and just having a really unhealthy, fat-filled diet that may include excessive amounts of saturated fats. Following the keto diet without remaining in ketosis may result in higher levels of unhealthy LDL cholesterol, especially if you’re eating your fair share of coconut or palm oils, lard, butter, cocoa butter, and red and processed meats, which are all high in saturated fat.
Because there is limited information on the long-term effects of the ketogenic diet, it is not generally recommended for the prevention of type 2 diabetes or heart disease.
When it comes to brain health, the ketogenic diet has shown promise in epilepsy, dementia (Alzheimer’s), ALS (amyotrophic lateral sclerosis), and traumatic brain injury. However, there’s also a lot of research suggesting that eating a Mediterranean-style diet or a variation of it, called the MIND diet, can result in dramatic memory improvements and preserve brain health.
And one notable study found that among middle-aged adults who were followed for about 25 years, eating a low carb diet (particularly one rich in animal protein and fat) was linked to a shorter lifespan compared with a more moderate approach. The findings suggested that eating around 50% of your calories from carbs was associated with the longest lifespan.
Some things to consider before trying the keto diet
Even though this diet can help with short-term weight loss, the biggest problem I see is that like many quick-fix diets, the keto diet is hard to sustain over time. At some point, you’ll encounter a situation—maybe a birthday party, a school event, or a happy hour—where the food is off-limits, and that type of restriction is tough to manage, particularly if you don’t have a solid plan in place for dealing with it.
Also, there are some short-term side effects, often referred to as the “keto flu,” which occur when your body is adapting to using ketones for fuel. They include:
Difficulty in exercise tolerance
These “keto flu” symptoms usually clear up within a few weeks.
There are also additional cautions for those with diabetes and anyone taking medications for blood sugar control. If you fall in this camp or if you have a serious health condition, please check with your doctor before starting a keto diet. It may not be appropriate to you or you may need to adjust your medications before you start or along the way.
On top of the difficulties I’ve seen among people trying to maintain the rigid keto guidelines, the long-term outcomes of maintaining a metabolic state of ketosis aren’t well-known right now. There isn’t much research on how the keto diet affects people after they discontinue it, or for those who continue beyond the first two years.
What you need to know before following the keto guidelines
As with any significant lifestyle change, sticking to the keto guidelines can be tough. Here are some questions you can ask yourself to determine if it’s right for you.
How much variety do you like in your diet? Sometimes the initial weight loss and blood sugar control is motivating, but once the honeymoon phase is over, you might be bored with the offerings. If you crave lots of variety, the keto guidelines might feel even more restrictive.
How well will you put up with side effects? The keto flu can be very de-motivating, so if you start feeling side effects, you might feel frustrated and find it hard continue.
Have you ever had a difficult relationship with food, your body, or your weight? Lifelong dieters, those with a history of yo-yo dieting, and those who have experienced disordered eating might be triggered by the restrictive nature of the keto guidelines. Any type of plan that takes a toll on your emotional health isn’t worth it!
What’s your reasoning for wanting to try the keto diet? Is it because you want to see results fast or something else? Always keep in mind that any type of fast results can only be sustained as long as you sustain the eating pattern that got you to those results. In other words, if you don’t foresee maintaining the keto guidelines, you might be better off with another eating pattern.
Do you have kids at home? Sometimes following restrictive eating patterns for the sake of losing weight can normalize an unhealthy desire for thinness, and this may influence your child’s relationship to food and his or her own weight. You’re a role model for your kids so think about how you model healthy eating and a healthy attitude towards your body and your weight.
Does your lifestyle involve a lot of socializing or traveling? If so, how realistic is it that you can follow the keto guidelines while dining out, during business meetings, or while traveling? Clearly, whatever eating pattern you follow should be realistic in your own life.
Nutrition tips for following the keto guidelines
If you’ve decided that you want to experiment with the keto diet, here are some things to keep in mind in order to practice it most healthfully.
Eat plant-based fats as often as possible. Extra virgin olive oil and avocado oil should be your go-to cooking oils and you should aim to get most of your fat from other plant sources, like nuts and seeds.
Pack your keto menu with healthful foods. Drastically reducing carbs means you're reducing healthful, protective compounds in your diet. Choose leafy greens, cauliflower, broccoli, Brussels sprouts, asparagus, bell peppers, cucumbers, mushrooms, onion, garlic, and to the degree possible, small amounts of berries to help meet your nutrient needs. In plain terms, make the most of your carb allowance!
Limit your intake of red and processed meat. These foods have been linked with an increased risk of serious diseases and they should be eaten in limited quantities no matter what eating pattern you’re following. A healthier keto diet includes fish and poultry as primary protein sources. (Processed meats make my list of the 4 worst processed foods to avoid. Check out the list here.)
Talk to your doctor or dietitian about supplements. Since the keto guidelines are so restrictive, it may be hard to meet all of your nutrient needs. You may benefit from a supplement to fill the gaps. (Read about the best supplements for your health here.)
If you want to geek out on the science with me, references are below:
Harvard Health Publishing. (2018, October). Should you try the keto diet? Retrieved from https://www.health.harvard.edu/staying-healthy/should-you-try-the-keto-dietHarvard Health Publishing. (2019, August). Can the keto diet help me lose weight? Retrieved from https://www.health.harvard.edu/staying-healthy/can-the-keto-diet-help-me-lose-weightMasood, W. & Uppaluri, K. R. (2019, March 21). Ketogenic Diet. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK499830/Shilpa, J., & Mohan, V. (2018). Ketogenic diets: Boon or bane?. The Indian journal of medical research, 148(3), 251–253. doi:10.4103/ijmr.IJMR_1666_18https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6251269/U.S. Department of Health and Human Services and U.S. Department of Agriculture. Office of Disease Prevention and Health Promotion. (2015, December). Dietary Guidelines for Americans 2015-2020, Eighth Edition. Retrieved fromhttps://health.gov/dietaryguidelines/2015/guidelines/appendix-7/https://www.thelancet.com/jour...