The ketogenic diet, often shortened to "keto," has become a popular weight loss strategy in recent years. The diet, characterized by very low carbohydrate and high fat intake, promises rapid weight loss. The truth is, while the little-to-no carb, high-fat diet can dramatically help shed pounds, there haven’t been any long-term, randomized clinical studies to help determine the long-term effects on the body. This article delves into the science behind the keto diet, its potential benefits and risks, and how to approach it safely and effectively.
What is the Keto Diet?
In its strictest form, the keto diet consists of 75 percent fats, 20 percent protein, and five percent carbohydrates. This macronutrient distribution shifts the body's primary fuel source from carbohydrates to fats. Under regular circumstances, cells in the body use carbohydrates as a source of energy, which is converted into glucose and sent into the bloodstream. When carbohydrate intake is drastically reduced, the body enters a metabolic state called "ketosis." During ketosis, the body breaks down fat molecules into something called ketone bodies to generate energy. It’s a catabolic process in some sense. It breaks down fat and muscle mass if you don’t take on calories,” Chokshi said. The main issue is that ketosis is arguably a backup mechanism for fuel and energy for the body, he said.
The Origins of Keto
The ketogenic diet's first recognized use was in the 1920s for the treatment of childhood epilepsy. In 1921, Dr. Russel Wilder first used this type of diet to treat epilepsy and described the term ‘ketogenic diet.’ Because of Wilder’s observed beneficial results, the KD assumed a place in medical nutrition as a therapeutic diet for paediatric epilepsy and was widely used until its popularity declined as antiepileptic agents were introduced. The KD acts by inducing a state of physiological ketosis, which has been linked metabolically to some anticonvulsant properties via reduced glucose, elevated fatty acid concentrations and enhanced bioenergetics reserves.
Potential Benefits of the Keto Diet
Weight Loss
Keto isn’t a magic weight loss diet. However, it can be an effective weight loss option over time. One review suggested that this low-carb diet can spur fat loss in people with obesity when used for a couple of weeks and for up to one year. And a meta-analysis noted that one likely reason for weight loss is that all of the fat consumed when on this diet may suppress hunger.
Several factors contribute to weight loss on a keto diet. First, insulin is a signaling hormone responsible for a number of functions in the human body – among them the retention by tissues of stored energy (fats and carbohydrates, predominantly) and to indicate a need for the storage of energy in circulation. Keto because of the composition of the calories, keeps a fairly heavy boot on circulating insulin levels. Limiting the brain’s requirement for glucose can be a very good thing. (In fairness, there is at least one study I am aware of which shows no such cognitive improvement).Higher fat and protein diets have greater satiety - if you feel full, you are less likely to eat too much.
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Improved Blood Sugar Control
That’s supported by several studies, like a 2017 review in the journal Nutrients that found that the keto diet improved HDL “good” cholesterol levels and helped reverse the course of type 2 diabetes in patients by controlling blood sugar levels, though “usually in limited time,” the researcher wrote. In 2018, another study in the journal Diabetic Medicine found the keto diet in patients with type 1 diabetes was associated with “excellent levels” of blood sugar. “I can see a potential benefit because diabetes is exacerbated by excessive carbohydrate intake,” he said.
Other Potential Benefits
Besides diabetes, the keto diet may also help improve short- and long-term cognition among people who are living with Alzheimer’s disease and experiencing mild cognitive impairment, according to a systematic review of randomized controlled trials. Researchers caution that further research is needed to confirm these findings and prove a cause-and-effect relationship between the ketogenic diet and preventing dementia.
Potential Risks and Downsides
Cardiovascular Concerns
Keto entails a significant portion of calories from fat, but not all fats are created equal. Consuming a lot of saturated fats, like the ones found in fast food and red meat, increases a person’s risk for atherosclerosis, which promotes coronary disease and heart attacks. Healthier fats-called monounsaturated and polyunsaturated fats-are found in foods like eggs, fish, and nuts. Additionally, keto can lead to a sudden surge in LDL and triglycerides, the “bad” cholesterol, when the diet is initiated, a surge that may level out after weeks and months. But, in the short term, having elevated LDL and triglycerides probably doesn’t do much in term of increasing a person’s risk of cardiovascular disease, Chokshi said.
There is one recent long-term study suggesting a risk for heart disease. It came from a group of Chinese researchers who presented a study at the American College of Cardiology annual meeting in New Orleans. They found patients who followed a diet low in carbohydrates for nearly two decades had an increased risk for atrial fibrillation. But there are important caveats to consider. While the study suggests a link between the two, it wasn’t a randomized trial, so it doesn’t show a cause and effect, and the participants weren’t on the keto diet. The researchers proposed that those at risk were probably eating fewer vegetables, fruits, and grains, which are known for being inflammation-fighting foods.
Nutrient Deficiencies
In one trial involving 33 people with prediabetes or diabetes, going on a ketogenic diet or a Mediterranean diet, which is a type of plant-based diet, for 12 weeks improved blood sugar control, as measured by A1C levels. That said, neither the low-carb, high-fat diet nor the plant-based diet performed better than the other. One benefit of the low-carb diet was that it reduced triglycerides better than the Mediterranean diet, and yet there were downsides: The keto diet increased LDL (“bad”) cholesterol, and those on the diet got fewer nutrients, particularly folate, vitamin C, magnesium, and fiber, because of everything that the keto diet cuts out (e.g., fruits, whole grains). The overall takeaway, researchers said, is that it’s best to work with your clinician on making an informed choice that is suited your health concerns, food preferences, and lifestyle.
Read also: Keto Calorie Counting: A Detailed Guide
Other Potential Downsides
Dehydration is typically characterised by dry mouth, headache, dizziness/orthostatic hypotension and electrolyte abnormalities (such as hyponatraemia and hypomagnesaemia), and visual disturbance is the most common short-term side effect.
Who Should Avoid the Keto Diet?
Here are some groups that should consider skipping, or at least adjusting, their ketogenic diet.
Extremely High-Level/High-Intensity Athletes
High-motor activities like Jiu-Jitsu, CrossFit and obstacle course racing may benefit from carb intake well above what is generally recommended for keto. With the added physical activity, you may still be producing ketones despite a greater carb intake. This is where following specific percentage recommendations can lead to problems.
Keto for a desk-bound programmer really does mean low carb. Keto in the context of a high-motor athlete can mean upwards of 200 grams of carbs per day depending on activity, size, intensity, and more. This is especially true if those carbohydrates come from nutrient-dense, high-fiber sources. However, it bears noting that I’m not dogmatic about carbohydrate intake. If your performance, recovery, and mental health need the additional carbs, suffering through deprivation won’t help you much.
Low-carb hyper responders
In a subset of people, a keto diet causes cholesterol levels (in particular, LDL-particle number) to shoot up. If you’re one of these “hyper-responders”, my advice is to tinker with the following:
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- Delete most dairy sources. For reasons that are not entirely clear, dairy may raise cholesterol and lipoproteins more than other foods, at least in some people.
- Shift as much of your fat as possible away from saturated fat to monounsaturated sources. Opt for leaner cuts of beef (don’t forget chicken and fish), and add in nuts, olive oil or avocados.
- Increase carb intake. Due to the effects of the ketogenic state on the enzyme HMGCO-Areductase, ketosis may directly increase cholesterol and lipoproteins in some folks. Just bringing carb intake up to 50-100g/day can dramatically decrease cholesterol and lipoproteins.
Pregnant or nursing women
Okay to eat keto with a baby on board? Another gray area. The answer is: it depends. Lilly Nichols, RD has used low-carb diets in hundreds of women struggling with gestational diabetes and a host of other issues. Some may be overtly in ketosis while others are just carb-restricted, but it is a safe and viable option depending on the person! Again, dogmatism and rigid adherence can be dangerous. A huge spectrum exists between keto and low-to-moderate carb intake. Even if lowering your carb intake turned out to be a good thing for you, more of a good thing is not inherently better. Monitor how you feel and adjust accordingly, always.
Those with gut issues
Depending on your situation, keto can either help or harm your gut. For instance, keto can alleviate small intestinal bacterial overgrowth (SIBO) by starving bad bacteria in your small intestine. Dr. Michael Ruscio wrote about this in his book, Healthy Gut, Healthy You. There has been some concern that limiting fermentable carbs can also degrade the gut barrier. That’s because, when gut bacteria have no fermentable carbs to eat, they eat the protective mucus lining in your gut instead, or so the theory goes. Five or ten years ago I was more concerned about this. Given how well folks have done on very low carb diets, even some carbohydrate-free diets (looking at you, carnivores!) … I think this concern may be either misplaced or may reflect certain individual predilections.
Individuals with Certain Medical Conditions
Those with epilepsy should also consult their doctor before using a ketogenic diet as part of their treatment plan.
How to Start a Keto Diet
Consult with a Healthcare Professional
Despite the potential blood sugar benefits of keto, because people with type 2 diabetes have an increased risk of heart disease, there is a specific concern that eating so much saturated fat may drive up LDL cholesterol levels and further increase the odds of heart problems. So, if you have type 2 diabetes, talk to your doctor before attempting a ketogenic diet, especially if you have other risk factors for heart disease, such as high blood pressure. The doctor may recommend a different weight loss diet for you that may help improve your blood sugar levels, such as a reduced-calorie diet. If you do opt to go through with the keto diet, consider working with a registered dietitian nutritionist who is also a certified diabetes care and education specialist. They can help you develop a healthy low-carb meal plan that is high in fat but low in saturated fats, and which contains plenty of healthy foods such as low-carb veggies.
Focus on Nutrient-Dense Foods
Keto done with a focus on nutrient denisity is basically paleo without the healthy carbohydrates. You can eat meat, fats, nuts, leafy greens, small portions of berries, and dairy if tolerated. Avoid high-carb foods like rice, sweet potatoes, grains, and honey.
Gradually Reduce Carbohydrate Intake
Inspired by Amy’s success? Step 1: Gradually cut carbs to 20 to 40 grams per day, eating keto versions of your favorite foods, suggests Dr. Tro. Your body will start turning fat into your main fuel, and that can help increase metabolism by 900%.
Listen to Your Body
Each of us has certain foods that just light up our brains, and that includes low-carb foods. For some people it might be processed meat; for other, it might be dairy,” he says. “I personally can’t stop eating almonds once I start, in part because they remind me of the almond cookies I ate growing up. But my wife can eat three almonds and it’s no big deal for her. Everyone is different. The idea is to build an arsenal of foods that fill you up without lighting up your brain. If zero-carb sweeteners aren’t an issue for you, you can have them. Dr. Tro himself is a fan of keto ice cream. You don’t even have to give up your trigger foods, he says. Just limit your exposure - maybe just enjoying them at restaurants - so they won’t be constantly stimulate your appetite. “You want to focus on the foods that make you feel full for a long time,” says Dr.
Focus on Foods That Promote Satiety
Step 3: Find your burger. Also pay attention to which foods let you go longest before you’re hungry again. Nothing beats a juicy burger for Amy, but eggs or salmon could be your magic food. Once you find it, enjoy it often - and stop eating when you’re not hungry, extending the time between dinner one day and your first meal the next. “The more you have to lose, the more you’ll benefit,” promises Dr. Tro. “It works much better and faster than counting calories.
Foods to Eat and Avoid on Keto
Here is a general guide to foods that fit into a ketogenic diet:
Protein
- Liberally: Grass-fed beef, Fish, especially fatty fish, like salmon, Dark-meat chicken
- Occasionally: Bacon, Low-fat proteins, like skinless chicken breast and shrimp. These are great to include in your keto diet, but add a sauce on top for some fat rather than eating them plain.
- Never: Cold cuts with added sugar (read the label), Meat that has been marinated in sugary sauces, Fish or chicken nuggets
Oil and Fat
- Liberally: Avocado, Avocado oil, Olive oil
- Occasionally: Limit your consumption of these oils, which should be easy to do if you’re avoiding packaged foods, where they’re often found. Sunflower oil, Safflower oil, Corn oil, Butter (just keep in mind that this is high in saturated fat), Heavy cream, Whole milk, Coconut oil
- Never: Margarine, Trans fats
Fruits and Veggies
- Liberally: Avocado (also high in healthy monounsaturated fat, and low in saturated fat, per the USDA), Leafy greens, like spinach and arugula, Celery, Asparagus
- Occasionally: These are great choices, but you’ll still need to count how many carbs they contain. Leeks, Spaghetti squash, Eggplant, Avocado, Raspberries, Lemon, Tomatoes
- Never: Potatoes, Corn, Raisins
Nuts and Seeds
- Liberally: Walnuts, Almonds, Flaxseed and chia seeds, Nut butter (unsweetened)
- Occasionally: Unsweetened nut butters (almond or peanut butter), Cashews, Pistachios
- Never: Trail mixes with dried fruit, Sweetened nut or seed butters, Chocolate-covered nuts
Dairy Products
- Liberally: Blue cheese, Feta cheese, Parmesan cheese, Cream cheese
- Occasionally: Full-fat cottage cheese, Full-fat plain Greek yogurt, Full-fat ricotta cheese, Cheddar cheese, American cheese
- Never: Milk, Sweetened nonfat yogurt, Ice cream
Sweeteners
- Liberally: None - always practice moderation with sweeteners. If you’ve tried other low-carb diets, this aspect of the keto diet probably won’t be surprising.
- Occasionally: Artificial sweeteners, such as stevia, Erythritol, Xylitol
- Never: Agave, Honey, Maple syrup, White and brown sugars
Condiments and Sauces
- Liberally: Guacamole, Lemon butter sauce, Mayonnaise (ensure that there’s no sugar added)
- Occasionally: Raw garlic, Tomato sauce (look for those with no added sugar), Balsamic vinegar
- Never: Barbecue sauce, Ketchup, Honey mustard
Drinks
- Liberally: Water, Unsweetened almond milk, Bone broth, Plain tea
- Occasionally: Black coffee (watch caffeine consumption), Unsweetened carbonated water (limit only if bubbles make you bloated), Diet soda, Zero-calorie drinks, Alcohol (hard spirits, wine, low-carb beer, some alcoholic seltzers)
- Never: Again, these are no-nos on all low-carb diets. Soda, Fruit juice, Lemonade
Herbs and Spices
All herbs and spices fit in a keto or low-carbohydrate diet, but if you’re using large amounts, Mancinelli recommends counting the carbs.
- Liberally: Salt (salt foods to taste only, to avoid raising blood pressure levels), Pepper, Thyme, oregano, paprika, and cayenne
- Occasionally: These are good choices, but they do contain some carbs. Ground ginger, Garlic powder, Onion powder
- Never: No herbs and spices are off limits; they’re generally okay to use in small amounts to add flavor to foods.
Supplements
- Consider taking Fiber, Multivitamin
- Optional MCT oil may help increase ketone levels more quickly, according to one small study. (Though research isn’t yet clear.) Mancinelli says she has no recommendation about taking or avoiding them.
Transitioning Off the Keto Diet
So you’ve followed the ketogenic diet for a few months now. You’ve achieved ketosis, lost some weight and (hopefully) experienced the intense mental clarity that keto-fanatics rave about. But after months of eating high fat, high protein and very little carbs, how do you reset your body to eat normally again?
“It probably took you a few days to get into ketosis when starting off on the keto diet,” says registered dietitian Kristin Kirkpatrick. “So a sudden influx of carbs and sugar could wreak havoc on your body if you go wild with your diet.”
If you don’t transition properly off the ketogenic diet, you could be setting yourself up for some not-so-pretty symptoms:
- Weight gain.
- Bloating and other bathroom issues.
- Blood sugar spikes, which could cause fatigue and irritability.
- Increased hunger and sugar addiction.
Instead, follow these three tips on how to effectively come off the keto diet.
Focus on hard to digest carbs
When looking to incorporate carbs back into your diet after severe restriction, Kirkpatrick recommends focusing on eating carbs that are high in protein and fiber.
“Bean based pasta, crackers with seeds or sprouted breads are all great options when looking to bring carbs back into your diet,” she says. “Even starting to add in cashews or more avocados are great additions.”
There’s a reason carbs stand for CarboHYDRATES. You’re naturally going to gain a few pounds when you reintroduce them back into your diet because they contain water. The key is to pick healthy, whole carbs that won’t cause gigantic spikes in your blood sugar. The worst thing you can do is go hog wild and start eating donuts and cookies. Instead, focus on the quality of the carbs and pick kinds that take more time to digest.Transitioning off the keto diet should take a few weeks. About 14 days is pretty reasonable for your body to adjust to the change. Some people find it helpful to increase their carb intake each day by about 10 percent, while others use an app to help keep track. Kirkpatrick suggests that the easiest way is to look at serving size and aim for two extra servings of carbs per day.
Be aware of the sugar pitfall
Don’t trade keto fat bombs for sugar bombs! One of the benefits of the ketogenic diet is the low sugar intake and eliminating added sugar in your diet.
“If you followed keto for a couple months, you probably noticed decreased sugar cravings,” says Kirkpatrick. “There’s research proving that sugar is addicting - so why would you want to go back to that?”
A good rule of thumb is to avoid anything with more than 4 grams of added sugar. Also be aware of too much naturally occurring sugar, which can hide in things like honey and certain fruits.
“If you have a bar that has 22 grams of sugar but it’s all from dates, that’s still not good and you’re going to spike your blood sugar,” she says.
Good habits help
When you first started keto, it probably took some time to educate yourself and learn about the diet. So coming off keto should be a similar and slow process.
“Weight loss isn’t just about the food - your environment, support system and lifestyle all play a factor in it,” explains Kirkpatrick. “So when keto is over and those things aren’t aligned correctly, it’s going to be easy to fall back into old habits and regain the weight.”
Staying hydrated is another important factor when working on healthy habits post keto. Being dehydrated causes irritability and can make you feel hungry when you’re actually just thirsty.
It all goes back to choosing healthy, balanced meals and snacks.
Keto and Hunger: Finding Your Satiety Sweet Spot
If you’re hungry on keto, what do you do? Tro Kalayjian, DO, a host of the Low Carb MD podcast, says his strategy works so well, it has even helped food addicts like Amy Eiges, who lost 224 pounds. Amy now works with Dr. Kalayjian - who is known as Dr. Tro - helping others get healthy and feel great. “All the years I suffered, there was a fairly simple strategy that could’ve healed me,” she says. “I don’t like being in the spotlight, but I want to spread the word.
What does he do differently? He asks dieters to worry less about carb counts and numbers on the scale and instead listen to their bodies. Everyone is different. The idea is to build an arsenal of foods that fill you up without lighting up your brain. If zero-carb sweeteners aren’t an issue for you, you can have them. Dr. Tro himself is a fan of keto ice cream. You don’t even have to give up your trigger foods, he says. Just limit your exposure - maybe just enjoying them at restaurants - so they won’t be constantly stimulate your appetite. “You want to focus on the foods that make you feel full for a long time,” says Dr.
Amy had met keto expert Tro Kalayjian, DO, at a keto convention. The doc, who had used keto to lose 150 pounds himself, agreed to see her. Amy went to the appointment armed with all the food logs to show how meticulous she could be even though the scale was doing in the wrong direction. Dr. Tro gave her food logs a quick glance. “Are you hungry?” he asked. She pointed to the logs. “I kept my carbs low.” He nodded. Amy was confused. If she was sticking to the plan, why did it matter? “What derails most people is hunger and cravings,” he told her. He explained his approach to keto relied heavily on satiety. And when you fix that - when you find ways to feel not just physically full but also psychologically content - you set yourself up for success.
Taking Dr. Tro’s advice, Amy noticed that nuts and bacon made her want to keep eating even when she was physically full. But chicken or a salmon? They make my brain say, ‘You’re good,’ she realized. She began planning meals around the most satisfying options. One big surprise: “If I go more than a day without beef, I feel ‘off,’” Amy reported to Dr. Tro. “Good!” he said. So instead of avoiding burgers as she once did, they became her secret weapon. She’d make them at home most days. They kept her satisfied for hours, and she felt better overall. On busy days, she’d hit the drive-thru for Quarter Pounders, tossing the buns. Steaks were a favorite too.
Impressed with Amy’s progress, Dr. Tro suggested she begin eating only when she felt hungry, a key trick for fast results. Amy found she usually didn’t want her first meal until 2 pm. She then had dinner at 7 pm. “I prioritized foods that made me feel content, and everything fell into place,” Amy says. She still has snacks and treats; she just doesn’t want them that often.