April 15, 2025
MS, Registered Dietitian, Former President of CT Academy of Nutrition & Dietetics
Table of Contents
The ketogenic diet, commonly known as “keto,” is one of these diets you hear friends and influencers talking about, making you wonder if it’s actually that healthy and worth a try.
And if you’re feeling overwhelmed by contradictory information or curious about whether keto might be your path to better health, we’ve got you.
In this guide, we cut through the “keto noise” and give you a clear, science-backed understanding of the ketogenic diet, not as a miracle solution but as one potential approach to consider on your wellness journey.
The ketogenic diet is a high-fat, very low-carbohydrate, moderate-protein eating pattern that fundamentally changes how your body produces energy.
While conventional dietary advice emphasizes carbs as the body’s primary fuel source, keto dramatically restricts carbs to under nearly 50 grams per day (think a medium bagel or a cup of cooked rice).
The keto diet prioritizes fat consumption instead of carbohydrates, which makes up approximately 70-80% of daily calories. Protein is kept moderate at around 15-20% of calories, with carbohydrates comprising just 5-10% of the total intake.
Unlike most modern low-carb diets, keto wasn’t born from a modern diet book or social media trend: it was developed in the 1920s at Mayo Clinic as a medical treatment for epilepsy.
Doctors had observed that fasting reduced seizure frequency in some patients, and the ketogenic diet was designed to mimic the metabolic effects of fasting while still allowing patients to eat.
While the diet continues to be used in medical settings, particularly for drug-resistant epilepsy in children, its application has spread beyond hospital rooms. Today, people explore keto for various reasons, from weight management and blood sugar control to potential benefits for certain neurological conditions and metabolic health optimization.
To understand what the keto diet does to your body, we should look at how our bodies typically use energy and what changes when we cut carbs. This process, known as ketosis, is the foundation of a ketogenic diet.
Normally, your body runs primarily on glucose (sugar) from carbohydrates. When you eat bread, pasta, fruits, or starchy vegetables, your system breaks these down into glucose, which provides quick energy for your brain, muscles, and organs.
When you drastically reduce carbohydrate intake, your body faces an energy challenge. Without its preferred fuel readily available, your body needs an alternative energy source to keep functioning. It thus enters a state of ketosis, the metabolic state where your body switches from using glucose as its primary fuel to burning fat instead.
Here’s ketosis explained in simple terms:
This remarkable metabolic shift is how keto works: by essentially forcing your body to become extremely efficient at burning fat for energy instead of carbohydrates.
The key to initiating this process is depleting your glycogen stores quickly, which is why cutting carbs dramatically is necessary. When you consume too much carbohydrates, your body preferentially burns those for energy and stores the excess as fat.
This shift to ketosis triggers important hormonal changes:
According to the research, nutritional ketosis is measured by blood ketone levels between 0.5 and 3.0 mmol/L, which results in stabilized blood sugar and minimized insulin release.
The transition to using ketones as fuel doesn’t happen instantly. That’s why any information on ketogenic diets for beginners is inevitably accompanied by the term “keto flu.”
The ketosis adaptation period in the first few days often includes flu-like symptoms in people (fatigue, headache, irritability).
Here’s what else most people experience during the keto-adaptation phase:
Full keto-adaptation typically takes 2-4 weeks, during which the body becomes increasingly efficient at producing and utilizing ketones for energy.
The ketogenic diet has been studied for various health conditions and metabolic states. While research continues to evolve, here’s what current evidence suggests about the potential benefits of keto.
One of the most common reasons people try keto is for weight loss. The research has repeatedly shown that ketogenic diets can be effective for weight reduction in the short term.
In a meta-analysis comparing low-carbohydrate ketogenic diets to low-fat diets, the researchers found that participants following ketogenic diets lost more weight than those on low-fat diets, resulting in decreased body weight, lower triglyceride rates (a type of fat in the blood) and lower blood pressure.
Here are a few reasons this happens:
Note: The long-term effectiveness of keto for weight management remains less clear. Some studies show that the initial advantage over other diets diminishes over time, suggesting that sustainability and adherence are crucial factors for any dietary approach.
The most compelling evidence for the ketogenic diet comes from research on blood sugar management and insulin sensitivity.
By dramatically reducing carbohydrate intake, keto naturally leads to lower blood glucose levels and reduced insulin requirements.
However, diabetes experts emphasize that medication adjustments for those with type 2 diabetes must be carefully supervised by healthcare providers, as insulin and other glucose-lowering medications may need significant adjustment to prevent dangerously low blood sugar.
The relationship between keto and heart health presents a more nuanced picture. While traditional views linked high-fat diets to increased cardiovascular risk, newer research suggests the type of fat and overall dietary pattern are more important than total fat intake.
Research indicates that well-formulated ketogenic diets may positively affect several heart health markers, such as decreased triglycerides, increased HDL (also known as “good”) cholesterol, and blood pressure.
This highlights a crucial point: diet quality matters a lot. A ketogenic diet rich in heart-healthy fats like olive oil, avocados, nuts, fish, and low-carb vegetables provides very different health outcomes compared to one full of processed meats and saturated fats.
Since the ketogenic diet’s original medical application was treating epilepsy, the diet naturally offers a range of potential neurological benefits, specifically for:
The neuroprotective mechanisms may include a more stable energy supply to the brain, reduced neural excitability, and decreased oxidative stress. However, research in this area continues to evolve.
Emerging research is exploring various other potential applications for ketogenic diets, including the benefits for hormone regulation and insulin sensitivity in women with PCOS and potential improvements in acne, possibly related to reduced inflammation and insulin levels.
While keto offers notable advantages for many people, it isn’t universally appropriate for everyone. Let’s explore who might benefit most from this approach and who might want to consider alternatives.
Based on current evidence, you might consider exploring a ketogenic approach under appropriate guidance if you:
Consider alternatives if you:
Before starting any significant dietary change, consulting healthcare providers familiar with low-carbohydrate approaches is a lifesaver for several reasons:
The Academy of Nutrition and Dietetics recommends working with a registered dietitian nutritionist (RDN) when making significant dietary changes, particularly for those with existing health conditions.
Here are the most common pitfalls to avoid:
For many people accustomed to decades of low-fat dietary advice, consuming enough fat on keto feels counterintuitive. However, fat is your primary fuel source on this diet.
Why does it happen? Cultural conditioning against fat, concerns about calories, or simply not knowing how to incorporate healthy fats into meals make you subconsciously question or even fear the extra fat intake.
Why is it a problem? Without adequate fat intake, you’ll likely experience persistent hunger, cravings, fatigue, and difficulty maintaining ketosis.
What should you do? Focus on incorporating healthy fats like olive oil, avocados, nuts, seeds, coconut oil, and fatty fish. Don’t fear adding butter to vegetables or choosing fattier cuts of meat if appropriate for your health status.
While protein is essential, excessive amounts can be converted to glucose through gluconeogenesis, potentially impacting ketosis.
Why does it happen? Many people coming from standard fitness or weight loss backgrounds are accustomed to high-protein recommendations.
Why is it a problem? Too much protein may make achieving and maintaining ketosis more difficult for some people.
What should you do? Most experts recommend a moderate protein intake of approximately 0.6-1.0 grams per pound of lean body mass, depending on activity level.
However, if you find yourself constantly battling strong cravings for meat and protein-rich foods while trying to maintain keto, your body might be telling you something important. Consider alternative approaches that still provide metabolic benefits without such strict protein limitations.
Intermittent fasting, for example, can promote similar fat-burning processes and ketone production while working with your body’s natural rhythms rather than fighting against persistent cravings.
Transitioning to ketosis causes significant changes in fluid and electrolyte balance, particularly sodium, potassium, and magnesium.
Why does it happen? Lower insulin levels increase renal sodium excretion, and most people reduce processed foods (a major sodium source) when starting keto.
Why is it a problem? Electrolyte imbalances contribute significantly to “keto flu” symptoms like headaches, fatigue, muscle cramps, and dizziness.
What should you do? Deliberately increase sodium intake through foods or by adding salt to meals. Include potassium-ric,h low-carb foods like avocados and leafy greens, and consider magnesium supplementation under healthcare guidance.
Many people view any deviation from perfect keto adherence as a complete failure, leading to unnecessary stress or abandonment of the approach altogether.
Why does it happen? Diet culture often promotes perfectionism, and the binary state of ketosis (you’re either in it or you’re not) can reinforce this mindset.
Why is it a problem? This rigid thinking creates unsustainable pressure and doesn’t account for life’s realities like social events, travel, or special occasions.
What should you do? Develop a more flexible mindset that allows for occasional planned deviations while having strategies to return to ketosis efficiently. Our guide to keto cheat days explores how to navigate occasional higher-carb meals while minimizing disruption to your progress.
Many foods contain “hidden” carbs that can add up quickly and interfere with ketosis.
Why does it happen? Carbs exist in unexpected places: sauces, spice mixes, dairy products, nuts, and non-starchy vegetables can all contribute meaningful amounts.
Why is it a problem? Unintentional carb consumption can prevent ketosis or cause fluctuations in energy levels and hunger.
What should you do? Track your food intake with a reliable app during the initial phase, read labels carefully, and be particularly cautious with packaged and processed foods.
While ketosis is the goal, becoming overly focused on ketone measurements at the expense of overall nutrition can be counterproductive.
Why does it happen? The measurable nature of ketones makes them an easy target for optimization, and social media often portrays higher ketones as “better.”
Why is it a problem? This approach may lead to nutritional imbalances or unnecessary stress about fluctuating ketone readings.
What should you do? Use ketone measurements as one data point among many, focusing equally on energy levels, hunger cues, and overall well-being. Remember that for most people, ketone levels above 0.5 mmol/L indicate nutritional ketosis.
The popularity of keto has spawned countless products labeled as “keto-friendly” that may not actually support your goals.
Why does it happen? Companies capitalize on trends, often with misleading claims or by using ingredients like sugar alcohols and fiber to reduce “net carbs” on labels.
Why is it a problem? Some products may have hidden impacts on blood sugar, contain inflammatory ingredients, or encourage overconsumption.
What should you do? Focus primarily on whole, unprocessed foods. If using packaged products, read ingredient lists carefully and research how specific ingredients may affect your metabolism individually.
Some keto beginners mistakenly reduce vegetables to avoid carbs, missing out on important nutrients.
Why does it happen? Fear of going over carb limits leads to excluding valuable plant foods.
Why is it a problem? Insufficient fiber and micronutrient intake can lead to constipation, decreased gut microbiome diversity, and potential nutrient deficiencies.
What should you do? Prioritize non-starchy vegetables like leafy greens, cruciferous vegetables, zucchini, asparagus, and peppers. Most of these foods are high in fiber and low in digestible carbs.
Weight loss is one of the most common reasons people try keto, and substantial evidence supports its effectiveness as a weight loss approach with important caveats and considerations.
There are several mechanisms that contribute to weight loss on keto:
However, despite these promising results, you should always assess these benefits in a wider context.
Weight loss varies significantly between individuals based on genetics, metabolic health, activity level, and adherence. And even though keto may make achieving this easier through appetite control, the fundamental principle of energy balance still applies: you need a caloric deficit to lose weight.
For fitness enthusiasts and those concerned about maintaining or building lean mass, the question of “Can I build muscle on keto?” is a common one.
To be frank, the relationship between ketogenic diets and muscle building is nuanced, yet it has its fair share of benefits and opportunities for muscle gain.
Сarbs have always been at the core of nutrition for fitness. And here’s why:
These factors have led many to believe that low-carb approaches are inherently disadvantageous for muscle building. However, emerging research presents a more complex picture.
Recent findings reveal that individuals can maintain and even build muscle on a ketogenic diet under the right conditions. When combined with sufficient protein intake (typically higher than standard keto recommendations) and properly structured resistance training, muscle preservation or growth appears possible.
Here are a few pointers on the strategies that will help you out:
The foundation of a successful ketogenic diet lies in food choices that support nutritional ketosis while providing comprehensive nutrition.
Fats provide the primary energy source on a ketogenic diet, but quality matters significantly. Focus on:
Protein provides essential amino acids while helping to preserve lean mass during weight loss.
The best sources of protein to pay attention to include:
Although some vegetables are high in carbs, you can’t eliminate them entirely from your diet. Instead, focus on the non-starchy veggies to get enough fiber, antioxidants, and micronutrients essential for long-term health:
While most fruits are too high in carbohydrates for keto, there are a few options safe enough to make it to your meal plan:
Hunger can strike between meals, and having satisfying, keto-approved options ready can make all the difference between staying on track and reaching for convenient (but carb-heavy) alternatives. Consider:
Often confused with beverages, liquid keto options can play a valuable role in a well-rounded ketogenic diet as full-on meals to add to your diet:
Liquid keto diet options can be particularly helpful during the initial adaptation phase, when traveling, or as a strategy to overcome plateaus.
Even if the keto diet is focused on replacing carbs with healthy fats, it doesn’t mean you should ignore balancing out all the macronutrients you consume.
For optimal nutrition, aim to include these components in most meals:
Using this approach, you’ll be more aware of your nutritional needs, possibly avoiding the risks of low-carb dieting.
Understanding these concerns can help you implement the keto diet more safely if you try it.
Many people experience temporary side effects during the initial transition to ketosis:
Most of these effects resolve within 1-4 weeks as the body adapts to using ketones for fuel.
Less is known about the long-term effects of ketogenic diets, but several considerations warrant attention:
To make sure you stay on the lookout, make it a habit to schedule regular health assessments, including:
If you decide to try a ketogenic approach, thinking about long-term sustainability from the beginning can improve your experience and outcomes. Here are some of the strategies you might consider to get the most out of your keto experience:
The research on the keto diet for men vs. women is still emerging, but there are already some interesting insights.
Recent studies have started exploring potential sex-based differences in response to ketogenic diets. One notable study used mouse models to investigate these differences.
The researchers found intriguing results: male mice on a ketogenic diet maintained blood glucose control and lost weight. In contrast, female mice gained weight and developed poorer blood sugar control than females on a standard diet.
When they removed the ovaries from some female mice (eliminating the primary source of estrogen), these mice then showed decreased body fat and maintained glucose control on the keto diet, similar to the male mice. This suggests that female sex hormones, particularly estrogen, might influence how the body responds to a ketogenic eating pattern.
While the findings are intriguing, it’s important to note that animal studies don’t always apply to humans, and hormone levels—particularly in post- vs. pre-menopausal women—may influence results more than biological sex alone. Individual factors like metabolic health, gut microbiome, activity level, and genetics likely play a bigger role, and human studies on gender differences in keto outcomes remain mixed.
As with any significant dietary change, consulting with healthcare providers familiar with your personal health history remains the best first step.
Despite its fame, the ketogenic diet is a significant shift from traditional dietary advice. As with any major lifestyle change, the decision to try keto deserves careful consideration of your individual circumstances, goals, and preferences.
Here’s what you should remember to make that decision:
If you’re considering keto, remember that no single dietary approach works for everyone. The ideal diet for you depends on numerous factors, including your:
Perhaps most importantly, sustainability matters more than short-term results. The best diet is one you can maintain consistently while supporting your overall health and well-being.
If you decide to explore a ketogenic approach:
Whatever dietary path you choose, approach it with patience, flexibility, and attentiveness to your body’s signals. Nutrition science continues to evolve, and the best approaches integrate current evidence with personal experience and individual needs.
Remember that the ketogenic journey is highly individual, and finding your personal approach is key to long-term success.
Weight loss varies significantly between individuals. Initial weight loss of 5-10 pounds in the first week is common, primarily representing water weight as glycogen stores deplete. After this initial drop, a more moderate pace of 1-2 pounds per week is considered healthy and sustainable for most people. Factors affecting weight loss speed include starting weight, metabolic health, activity level, age, gender, and strict adherence to the diet.
Nutritional ketosis is different from ketoacidosis, a dangerous condition primarily affecting people with type 1 diabetes. In nutritional ketosis, ketone levels remain controlled (typically 0.5-3.0 mmol/L), while ketoacidosis involves extremely high ketone levels (usually >10 mmol/L) along with high blood glucose and requires emergency medical treatment.
That said, ketogenic diets aren’t appropriate for everyone, and potential risks exist, as outlined in the Risks and Considerations section. Working with healthcare providers familiar with low-carbohydrate approaches can help ensure safety.
While many people naturally reduce calorie intake on keto due to increased satiety and its somewhat restricted nature, the fundamental principles of energy balance still apply. If weight loss stalls, examining calorie intake may be helpful. Some individuals find they can maintain a healthy weight without explicit calorie counting by listening to hunger and fullness cues, while others benefit from more structured tracking.
Individualized supplementation based on personal needs, dietary intake, and blood work is ideal. However, common considerations include:
Consulting with healthcare providers about specific supplementation needs is recommended, as requirements vary based on individual factors and health conditions.
Alcoholic beverages vary significantly in carbohydrate content. Hard liquors like vodka, whiskey, tequila, and gin contain minimal carbs and can fit within ketogenic macros, while beer, sweet wines, and cocktails typically contain significant carbohydrates. However, several important considerations exist:
If you choose to consume alcohol, opt for lower-carb options, stay well-hydrated, and consider reduced serving sizes.
Restaurant dining on a ketogenic diet requires some strategy. Here are some tips:
Most restaurants can accommodate low-carb requests with simple modifications to standard menu items.
This article is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional advice or help and should not be relied on to make decisions of any kind. Any action you take upon the information presented in this article is strictly at your own risk and responsibility!