An essential guide to the keto diet: What is it and does it work?

The ketogenic diet has been gaining popularity over the last several years, with interest spiking in 2019 and remaining fairly steady since. ¹ 

While some may disregard the keto diet as a fad, research on the diet has also soared, with over 400 publications from 2005-2024 with a notable upward trend from 2017-2023. ² There are many benefits to following a ketogenic diet, and understanding how it works is the first step toward deciding whether or not it‘s right for you.

Read on to learn more about what the ketogenic diet is and what the potential benefits of eating this way are. We’ll also look at considerations for adopting this type of dietary pattern, as well as key foods to enjoy (as well as the ones to avoid) if you want to try a keto approach. 

What is a keto diet?  

The ketogenic diet is a high-fat, moderate-protein, and very low-carbohydrate dietary pattern that simply and efficiently changes your metabolism. ³ 

When eating high amounts of carbohydrates, the glucose from those carbohydrates becomes your body’s main source of fuel. Your body releases a hormone called insulin in response to the carbohydrates to move the glucose into your cells to use for energy.  

When you reduce your carbohydrate intake, the stored glucose in your liver and muscles (known as glycogen), as well as the glucose you get from food, decrease dramatically and your insulin levels also go down. 

Both the low availability of glucose as well as low insulin levels stimulate your body to look for alternative fuel sources. This is where ketones come in. 

Your body uses both the fat you eat as well as the fat stored in your body to produce chemicals called ketones, which most tissues in the body can use as an alternative fuel source to glucose. ³ 

There are various types of ketogenic diets. While all limit carbohydrates, the degree to which you restrict both carbs and protein depends on the goals of diet. For most people using this approach, a typical distribution of macronutrients is around: ⁴ 

• 55-70% fat 
• 20-35% protein 
• 5-10% carbohydrates 

This typically means keeping carbohydrates to around 30-50 grams (g) per day. At this level, your body will transition to a state commonly known as “nutritional ketosis,” where the majority of your fuel is coming from ketones instead of glucose. ⁵ 

Benefits of a keto diet 

Many of the benefits of a ketogenic approach come from relying on fat for fuel instead of glucose, as well as the signaling effects of ketones within the body. ³ 

As mentioned, research on the keto diet has soared in recent years with more and more studies exploring potential benefits to this dietary pattern. The areas with the most evidence include: 

Weight loss 

Studies show that people following a ketogenic diet tend to have lower insulin and blood sugar levels and can lose weight without counting calories. ⁶ 

The ketogenic diet may also help with the following: ⁷ 

• Reducing hunger hormones 
• Reducing the fat around your organs (visceral fat) 
• Preserving muscle mass and resting metabolic rate (RMR) when you lose weight 

One of the challenges with most diets that restrict calories to achieve weight loss is the reduction in RMR, which is the amount of energy your body uses up during low-effort activities (think: eating or walking a short distance). This is hypothesized to be due to the loss of muscle that accompanies most weight-loss approaches. 

This reduction in how many calories your body burns at rest per day may be one of the reasons it can be hard to maintain weight loss long-term. With a keto approach, however, you can preserve your muscle mass and RMR when losing weight, making it a great option for anyone looking to drop pounds. ^7,8 

Metabolic syndrome, prediabetes, and diabetes 

These three conditions all share a common factor: underlying insulin resistance. The difference is just the severity of the insulin resistance and whether it's reached a point in which blood sugar control starts to be compromised. 

Your body produces insulin to transport glucose into cells to be metabolized. Carbohydrates require insulin to be metabolized and used, so it would make sense that a diet restricting carbs would be an effective way to treat anyone with signs of insulin resistance. 

Research has consistently shown that low-carb diets reduce both insulin and blood sugar, therefore improving overall glycemic control and insulin resistance in healthy people and those with diabetes. ^6,7,9

In fact, current evidence shows that people diagnosed with prediabetes or type 2 diabetes can reverse the condition while reducing or stopping medications when following a keto diet. ^10,11 

Cardiovascular disease 

Cardiovascular disease (CVD) is the leading cause of death for people with diabetes. ¹² In addition to improving glycemic control and insulin resistance, the keto diet has been shown to reduce major risk factors for CVD including the following changes: ^10,13,14 

• Reduced overall inflammation 
• Healthier levels of blood fats 
• Lowered blood pressure 

While some may notice an increase in low-density lipoproteins (LDL), referred to by some as “bad cholesterol,” studies are indicating that this may not be a concern when other risk factors for CVD are all improved. ¹⁵ CVD risk factors that can improve when following a low-carb or keto diet include: 

• Blood sugar 
• Insulin 
• Triglycerides 
• HDL or “good cholesterol” 
• Inflammation 
• Blood pressure 
• ApoB 
• Small LDL-P  

Possible benefits that researchers are investigating 

Additionally, research is starting to highlight the keto diet could have a role in the treatment or improvement of other areas of health, including: ^7,16,17

• Alzheimer’s disease 
• Cancer 
• Polycystic ovary syndrome (PCOS) 
• Mental health 
• Acne 
• The gut microbiome, which is the community of microbes living in our digestive tract  

Keto diet side effects and risks 

Now that we’ve outlined several of the potential benefits of the keto diet, what about the risks?  

Keto flu 

The switch from using carbohydrates as your primary fuel to primarily using fat often causes some short-term, but easily managed side effects commonly referred to as the “keto flu.” ¹⁸ 

When insulin levels drop, our kidneys start to excrete more fluid. But we don’t just lose water. Insulin also plays a huge role in how much sodium we retain, meaning that when we enter ketosis, we start excreting larger amounts of both water and sodium. ¹⁹ 

If you don’t replace these fluids and sodium, you can experience symptoms like: 

• Lightheadedness 
• Fatigue 
• Headache 
• Constipation 
• Nausea 

The good news is that you can easily mitigate these symptoms by drinking plenty of fluids and adding extra sodium to your daily intake. ²⁰ 

Easy ways to include extra sodium in your diet include: 

• Drinking 1-2 cups of broth 
• Eating sodium-rich foods like pickles and soy sauce 
• Buying or making your own electrolyte mix to add to drinks 

When it comes to electrolyte mixes, you’ll want something that contains at least 500 milligrams (mg) of sodium per serving and very little or no added sugar. 

It’s also important to pay attention to other electrolytes like potassium and magnesium, which you can find in low-carb foods such as: 

• Avocados 
• Leafy greens 
• Nuts  
• Seeds 
• Fatty fish 
• Unprocessed meats 

It’s best to get your potassium from foods instead of supplements. Potassium supplements aren't recommended unless prescribed due to potential complications with excessive potassium supplementation. You may choose to take a magnesium supplement if you’re experiencing negative symptoms like disrupted sleep or muscle cramps.  

It's best to speak to your doctor before adding new supplements to your diet.  

Effects on medications 

Following a ketogenic diet while taking certain medications for diabetes or blood pressure could lead to complications. ²¹ Because of the effects this eating pattern can have on your glucose and fluid levels, it’s important to discuss it with your healthcare provider if you use any of the following medications:  

• Insulin 
• Sulfonylurea 
• Hypertension medications 
• SGLT2 inhibitors  

Depending on the medication, following the keto diet could potentially lead to a dangerous blood glucose crash, low blood pressure, or a life-threatening condition called diabetic ketoacidosis. ²¹ 

You can mitigate these risks by working with a healthcare professional who can monitor and adjust your medications as needed. 

Sustainability 

A common concern about the ketogenic diet is its sustainability over the long term. However, recent studies have shown that with proper guidance and support, individuals have been able to successfully stick to the keto diet for extended periods ^22,23 with sustained improvement in markers of metabolic health. ²² 

What to eat on a keto diet  

As mentioned, a ketogenic diet is a high-fat, moderate-protein, and low-carb dietary pattern. This means most of your diet will be composed of protein and fat with minimal carbohydrates coming from non-starchy vegetables, nuts, and seeds.  Foods to focus on when following a keto diet are: 

• Meat and poultry, such as beef, pork, chicken, and turkey 
• Seafood, such as salmon, trout, tuna, and shrimp 
• Full-fat dairy, such as cheese, cream, butter, and unsweetened Greek yogurt 
• Eggs: whole eggs, including the yolk 
• Non-starchy vegetables, such as green veggies, cauliflower, peppers, and onions  
• Low-glycemic fruits, such as berries, avocados, olives, and tomatoes 
• Nuts and seeds, such as almonds, walnuts, pumpkin seeds, and chia seeds 
• Minimally processed oils, such as avocado oil and olive oil 
• Condiments, such as salt, pepper, spices, herbs, soy sauce, and vinegar 

Here’s an easy step-by-step guide to putting together a keto-friendly meal: 

1. Pick a quality source of low-carb protein such as beef, seafood, eggs, Greek yogurt, or tofu. 
2. Add at least one serving of non-starchy veggies like greens, cauliflower, broccoli, peppers, or asparagus. 
3. Add a source of healthy fats such as olive oil, butter, or sour cream. 

Sometimes you may get enough fat in the protein you’re eating, while other times it’s a great idea to cook with fat or add it before eating.  

One way to track if you are getting enough fat is to pay attention to how soon you feel hungry again after eating a meal. 

If you're meeting your protein needs and feel hungry within a few hours of eating, it’s a good idea to add a little more fat. If, however, you can go very long stretches without wanting to eat, you may want to back off on the fat you’re adding to meals. 

The sweet spot is to feel hungry enough to eat two to three meals per day, but also not feeling ravenous 1-2 hours after you finish a meal.  

What to avoid on a keto diet  

Insulin is the main hormonal driver of ketosis, ²⁴ so it‘s important to limit foods that stimulate a high insulin response when following a ketogenic diet. Additionally, because most of your calories will come from fat, it’s important to focus on eating minimally processed fats (think monounsaturated or saturated fats). These are easier for your body to use as fuel when carbs are low. ²⁵ When following a keto approach, it is best to avoid the following foods: 

• Grains, such as rice, pasta, bread, oats, flour, and quinoa 
• Starchy veggies, such as potatoes, corn, and winter squash 
• High-GI Fruits, such as apples, pears, watermelon, cherries, and bananas 
• Sugary foods, such as soda, sport drinks, cakes, cookies, and fruit juice 
• Certain dairy, such as milk and high-sugar yogurt 
• Beans and legumes, such as peas, black beans, lentils, chickpeas, and kidney beans 
• Sugary condiments, such as BBQ sauce, ketchup, honey mustard, and teriyaki 
• Highly processed fats, such as anything with vegetable oils or partially hydrogenated oils   

The good news is there are many great low-carb substitutes for your favorite high-carb foods. Here are some swaps you could try: 

• Using almond flour in place of regular flour 
• Swapping cauliflower rice for regular rice 
• Spiralizing zucchini to use instead of pasta 

Tips and tricks for following a keto diet 

It can be tough to adjust to this way of eating, especially if you’re used to more carbohydrates in your diet. It may take time to get comfortable with a new eating routine, so here are some tips and tricks that could help you get started: 

• Plan your meals in advance and make a shopping list. Having keto-friendly foods on-hand can make or break keeping your carbs low.  
• Remove the carbs. If you’re not able to get rid of the carbs in your kitchen completely due to what foods others in your household are eating, try keeping them out of sight to lessen the temptation as you adapt to a low-carb approach.  
• Stock up on keto-friendly snacks. Try things like string cheese, olives, nuts, veggies with dips, beef jerky, hard boiled eggs and avocado, or cottage cheese. 
• Be sure to drink plenty of fluids throughout the day. 
• Include 1-2 g of extra sodium in your diet by drinking broth or adding high-sodium foods like pickles or soy sauce to your meals. 
• Look for low-carb versions of your favorite foods or recipes. You can find a replacement for almost anything online, including desserts. 
• Look up menus in advance when dining out. Focus on protein and vegetable-based dishes and make swaps when needed; try ordering extra veggies, skipping the potatoes, or ordering a burger or sandwich without the bun. 

Sample day of keto eating 

Here are some example meals you could eat over the course of a day of eating the keto way: 
 
Breakfast: 

• Three-egg omelet with veggies and cheese with a side of bacon. 
• Full-fat plain Greek yogurt with a handful of berries and nuts. 
• Protein waffles (mix 1 egg, 1 scoop protein powder, water or cream to desired consistency, then cook in waffle maker or make pancakes on the stove) topped with butter or a handful of berries. 
• Leftovers from lunch or dinner (you don’t have to eat “traditional” breakfast foods!). 

Lunch: 

• Big salad with chicken, steak, or salmon topped with olive oil-based dressing. 
• Burger in a lettuce leaf with roasted veggies or a side salad. 
• Mac and cheese made with zucchini noodles. 
• Poke bowl with mixed greens. 

Dinner: 

• Steak with veggies and side salad. 
• Salmon Caesar salad. 
• Pasta carbonara made with zucchini noodles. 
• Pan-fried tofu with mashed cauliflower and roasted veggies. 

A final note from Lingo  

The ketogenic diet has been gaining popularity in recent years. It can help with stabilizing blood glucose, reducing insulin, cardiovascular health, and weight management. 

Adapting to a ketogenic diet requires a major metabolic shift, switching from primarily burning carbs for fuel to burning fat. Once you’ve made the transition, you may start to notice more stable blood glucose as well as improved energy and focus as your body taps into fat as a source of fuel. 

It's important to work with a healthcare professional if you are on medications that need adjusting with this way of eating.  

Using a continuous glucose monitor (CGM) like Lingo can help you navigate foods that keep your glucose levels low. Doing so can mean lower insulin levels and a higher reliance on ketones for fuel.   

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