The ketogenic diet puts your body into a state of ketosis, which ultimately allows you to use fat for energy.
Fat burning is just one of the many benefits of ketosis that improves overall health and makes it an effective tool for weight loss.
Keto has a cult following for a good reason: it makes you feel great. Keto-ers feel more satiated throughout the day and have increased energy levels, both physical and mental, leading to:
Lower caloric intake
More physical activity.
These benefits all contribute to weight loss; however, keto is not synonymous with weight loss.
Far from being a magic tool, the ketogenic diet takes accurate and diligent tracking and adjustment to work. You need a balance of the right macros, realistic goal setting and tracking to take you closer to achieving your weight loss goals.
By the end of this guide, you’ll have everything you need to get started on the ketogenic diet to lose weight the right way — for the long term.
What is Ketosis & How Does It Promote Fat Loss?
The ketogenic diet promotes and maintains ketosis.
Ketosis is a metabolic state in which your body uses fat rather than glucose from carbohydrates as its primary source of energy.
To achieve ketosis, you stop supplying your body with carbs and sugar. This depletes your stored glucose — also known as glycogen — and your blood sugar and insulin levels decrease. Your body starts to look for an alternate source of fuel (fat), releases it and burns it for energy.
Hence, weight loss on keto.
Because of the decrease of glucose and increase in the metabolism of fat, ketosis has a ton of benefits — its unique ability to induce weight loss is just one of them. Many people use ketosis as a treatment for epilepsy, diabetes and even cancer.
When your body burns fat, it produces ketones. Without ketones, you’re not in ketosis. Therefore, the ketogenic diet’s sole purpose is to aid and promote ketone production.
WHAT ARE KETONES?
Ketones are the metabolic fuel produced when your body shifts into fat-burning mode.
Glucose and ketones are the only energy sources used by the brain. Think of ketones as the auxiliary power source of your body.
Before the advent of agriculture, when our ancestors were hunter-gatherers, they fasted regularly. When food was scarce, they didn’t have a choice but to wait for an opportune time to hunt for food and cook it.
They had a very low intake of carbs and protein and thus were unintentionally running on ketones. Converting stored fat into energy is hardwired for our survival and a natural part of human existence.
Your body burns fat to use and produce ketones whenever glucose sources are low or depleted, such as:
after prolonged exercise
when you eat a ketogenic diet.
Lipase (an enzyme responsible for fat breakdown) releases stored triglycerides (fats). These fatty acids go to your liver and your liver turns them into ketones.
There are three types of ketone bodies:
Acetoacetate – During the breakdown of long- and medium-chain fatty acids for energy, acetoacetate is produced first.
Acetone – Spontaneously, acetone is also produced as a by-product of acetoacetate. Both of these ketone bodies, when not used, spill into your urine and breath, making urine and breath testing a promising measurement of whether or not you’re going into ketosis. More on this below in How to Test Ketone Levels.
Beta-hydroxybutyrate (BHB) – Not technically a ketone but a molecule. Its essential role in the ketogenic diet makes it count as the important ketone body. BHB is synthesized by your liver from acetoacetate. BHB is important because it can freely float throughout your body in your blood, crossing many tissues where other molecules can’t. It enters the mitochondria and gets turned into ATP (adenosine triphosphate), the energy currency of your cells. BHB = ATP = energy!
Now that you know what ketones are and how ketosis works, you probably want to know why you should consider eating a ketogenic diet — the diet that promotes ketosis.
The Benefits of Ketosis
The benefits of ketones come from your body burning fat for fuel and the lowered glucose and insulin in your blood.
The benefits of ketosis include:
Body fat burning
Mental clarity and increased cognition
Improved physical energy
No feeling of deprivation because you experience less hunger[*]
Steady blood sugar levels from little to no intake of refined carbs
Skin improvements in those with acne[*]
Improved triglyceride and cholesterol levels[*]
Hormone regulation — women who go on keto report less severe symptoms of PMS[*].
Aside from the therapeutic benefits of ketones, many people fall in love with keto because of the way it makes them feel both mentally and physically.
The Ketogenic Diet Weight Loss Results
The ketogenic diet is an effective tool for weight loss because of the dramatic decrease in carb intake, forcing your body to burn fat instead of carbs for energy.
Results vary among individuals due to several factors such as insulin resistance and unique body composition. Nonetheless, keto has consistently lead to a reduction in weight and body fat percentage in a wide range of situations including but not limited to obesity, type 2 diabetes and athletic performance.
A randomized control study in 2017 examined the effects of a ketogenic diet combined with Crossfit training on body composition and performance. Results from this study concluded that subjects following a low-carbohydrate ketogenic diet (LCKD) significantly decreased body weight, body fat percentage and fat mass compared to those in the control group[*].
The subjects following the ketogenic diet:
Lost an average of 3.45 kilograms (7.6 pounds) compared to those in the control group who had no loss in body weight.
Lost an average of 2.6% body fat while those in the control group did not lose any body fat.
Lost on average 2.83 kilograms (6.2 pounds) of fat mass (the portion of the body composed strictly of fat) compared to the control group who did not lose any fat mass.
Maintained lean body mass to the same degree as those in the control group.
Improved Crossfit performance to the same degree as those in the control group.
Dashti et al. performed a study in 2004 observing the long-term effects of a ketogenic diet in obese patients and found the following[*]:
The weight and body mass index of the patients decreased significantly.
The level of total cholesterol decreased from week 1 to week 24.
HDL cholesterol (the good one) levels significantly increased.
LDL cholesterol (the bad one) levels significantly decreased after treatment.
The level of triglycerides (fat) decreased significantly following 24 weeks of treatment.
The level of blood glucose significantly decreased.
Partsalaki et al. carried out a study in 2012 comparing the effects of a ketogenic diet versus a hypocaloric diet in obese children and adolescents. Results showed[*]:
Children following the ketogenic diet significantly reduced body weight, fat mass, waist circumference and fasting insulin levels.
The children in the ketogenic diet group significantly reduced a marker of insulin resistance known as homeostatic model assessment-insulin resistance (HOMA-IR) to a greater degree than those following a hypocaloric diet.
An important marker of insulin sensitivity and cardiovascular disease — known as high molecular weight (HMW) adiponectin — significantly increased in the ketogenic diet group but not in the hypocaloric diet group[*][*].
Additionally, a 2008 study looking at the effects of a low-carbohydrate ketogenic diet versus a low-glycemic index diet in type 2 diabetics was conducted.
Results from this study concluded that participants following the ketogenic diet had significantly greater improvements in weight loss, hemoglobin A1c, and high density lipoprotein (HDL) cholesterol compared to the low-glycemic index diet group[*]:
Those following a ketogenic diet:
Lost on average 11.1 kilograms (24.5 pounds) compared to those following the low-glycemic index diet who lost on average 6.9 kilograms (15.2 pounds)
Reduced their HbA1c levels by 1.5% compared to the low-glycemic index diet group who only reduced their HbA1c levels by 0.5%.
Increased their HDL cholesterol on average 5.6 mg/dL compared to those in the low-glycemic index group who had no increases in HDL cholesterol.
Diabetes medications were reduced or eliminated in 95.2% of participants in the ketogenic diet group vs. only 62% of participants in the low-glycemic index group.
The ketogenic diet works for weight loss because it’s based around high fat, adequate protein and very low carb intake.
BUT I THOUGHT FAT WAS BAD FOR YOU?
There’s a common misconception that fat is bad for you; however, this misconception fails to adequately represent healthy fats which are actually good for you.
Aside from other scientifically-proven benefits, saturated fats like medium-chain triglycerides (MCTs) go directly to your liver to be used for energy.
The ketogenic diet, with its high percentage of good fats, leads to a fat-adaptive metabolic state.
Fat-adaptation occurs when your body becomes more efficient at burning fat for fuel. The longer you maintain a fat-adaptive state, the more ketones you produce.
The goal of a ketogenic diet is to maintain high amounts of ketones so you can reap all of the benefits that occur from being in ketosis.
A high fat, ketogenic diet is also protein-sparing: your body keeps burning fat and doesn’t turn to protein as an energy source.
HOW MUCH PROTEIN CAN I REALLY EAT?
Protein is extremely important on keto as well. Ideally, you should consume 0.8 grams of protein per pound of lean body mass. This will prevent muscle loss.
To calculate your lean body mass, you have to:
Calculate your body fat percentage. Click here to read how.
Subtract your body fat % from 100%. This will be your lean body mass %.
Multiply your lean body mass % by your total weight.
Worried that 0.8 grams per pound of lean body mass is too much protein?
The truth is that on a keto diet, you can eat a lot more protein than the standard 10-15% of total calories (that some other sources promote) without being kicked out of ketosis.
Too much protein won’t raise your blood glucose and decrease your ketone levels. That’s just a myth.
Check out the video below by Perfect Keto founder Dr. Anthony Gustin to understand the role protein plays on keto, why we recommend a higher protein intake, and why gluconeogenesis is not a problem:
LOW-CARB IS NOT KETOGENIC
The difference between ketogenic and low-carb diets is that the ketogenic diet aims for ketosis.
Other low-carb diets may not have a large enough decrease in carb intake to shift your metabolism into producing and burning ketones for fuel.
But, certain types of keto diets do have some leeway with carb and protein intake.
THE 4 TYPES OF KETOGENIC DIETS
Like intermittent fasting, you can customize the ketogenic diet according to your goals or needs.
There are four common types of ketogenic diets:
The Standard Ketogenic Diet (SKD): Most common and recommended version of the diet:20-50 grams of net carbs per day, moderate protein intake and high fat intake.
Targeted Ketogenic Diet (TKD): “Targeted” for energy around your workouts: 25-50 grams of net carbs or less around 30 minutes to an hour before exercise
Cyclical Ketogenic Diet (CKD): Similar to intermittent fasting “Down Day Up Day” or the 5/2 cycle, CKD involves eating a low-carb, ketogenic diet for several days followed by a couple days of eating high-carb.
High-Protein Ketogenic Diet: The SKD alternated with additional amounts of protein that could be ideal for more elite athletes
WHAT TO EAT AND WHAT TO AVOID ON THE KETO DIET
Ketogenic foods are high quality, whole, natural foods processed as little as possible. To avoid processed foods, many keto-ers prefer to make everything themselves, from burgers to homemade ghee).
Ketogenic foods are high in fat, adequate in protein and of course, low carb.
The most common mistakes on a ketogenic diet include not watching the quality and composition of your food and being careless about your carb intake.
To lose weight on keto you must:
Count carbs — even hidden carbs found in spices, vegetables and drinks.
Watch your sugar intake: this includes sweeteners, fruit and naturally occurring sugars in dairy. If you must use a sweetener, stick with stevia or opt for other keto-friendly sweeteners.
Watch your calories. Don’t exceed your calorie budget. To lose weight you need to eat less than what you burn. All calculations and metrics are discussed below.
Be conscious of your food in general. Avoid processed food. No matter how low-carb or “keto” it may be, if it’s full of junk you’re better off avoiding it.
Drink plenty of water. Carbs are famous for retaining water, so keto’s very low-carb ratio can lead to faster dehydration and constipation. Compensate with water and keto-friendly drinks.
Try intermittent fasting to avoid late night binges and speed up your ketone production and weight loss.
Your carb and protein intake makes (or breaks) your ketogenic diet. You can tweak your macros according to what works for you, but the general macronutrient ranges are:
These can vary according to your goals, needs and body composition. Designing your ketogenic diet involves calculating your macros.
Keto vs. Popular Weight Loss Diets: Atkins, Paleo, Mediterranean
Keto has been called “Atkins on steroids” and is often compared to other diets like paleo and the Mediterranean diet. What are the similarities and differences between keto, Atkins, paleo and the Mediterranean diets?
Well, to start, all four diets are centered around whole food. Any of these diets can be used to achieve your desired weight and health goals but the main differences come down to the macro distributions and of course, ketosis.
KETO AND ATKINS
The Atkins diet, formally called the Atkins Nutritional Approach, was founded by cardiologist Dr. Robert Atkins as a weight loss tool based on the idea of “eating right, not less.”
The similarities: Both the ketogenic and Atkins diets reduce your intake of carbs and sugar while shifting you toward eating whole, healthy foods.
If done correctly, the result is ketosis, weight loss and better mental acuity and physical energy from the steady fuel of ketones.
The difference: Atkins has four phases. The induction and balancing phases (Phase 1 and 2) resemble the ketogenic diet most closely.
Phase 1 (Induction) includes consuming very low carbs at 20-25 grams of net carbs per day. After induction, you slowly reintroduce and increase your carb intake again, until you find the perfect amount that satisfies you without resulting in additional weight gain.
Phase 2 (Balancing) has 25-50 grams net carbs per day.
Phase 3 (Fine-tuning or pre-maintenance) has 50-80 grams net carbs per day.
Phase 4 (Maintenance) has 80-100 grams of net carb intake daily.
In the ketogenic diet, the carb, protein and fat macros are sustained in their allotted portions to induce and maintain a state of ketosis.
The Pros of Atkins:
Can be easier to maintain than keto, especially for people who have difficulty avoiding carbs.
Ideal for beginners to experience ketosis and all the benefits in the initial phases while experimenting with different variables and then maintaining ketosis if they choose to.
KETO AND PALEO
The paleo or paleolithic diet — also called the caveman diet, hunter-gatherer diet or Stone Age diet — is based on consuming the foods available to our ancestors in their hunter-gatherer days and the early days of agriculture,about 10,000 years ago.
With paleo, processed food is out. This means no sugar or flour-based foods since producing sugar and milling wheat wasn’t invented yet back then.
Anything you could hunt, catch, pick or dig from the ground easily is in, such as meat, seafood, fruits, nuts and vegetables.
The similarities: Both the ketogenic and paleo diets are rich in non-starchy vegetables. Both also restrict sugar, grains, legumes and recommend high-quality animal proteins and fats.
As long as your gut doesn’t have a problem breaking them down, keto is perfectly okay with full-fat, all natural dairy — cheese, butter, ghee. Conversely, paleo avoids anything that can compromise the gut like dairy.
Compared to the very low carb restriction of the ketogenic diet, paleo does not restrict starchy vegetables and sugary fruits, making it close to impossible to get into ketosis.
The Pros of Paleo:
Can be ideal for fitness buffs who perform daily, high-intensity exercises.
Good for vegetarians and vegans.
KETO AND THE MEDITERRANEAN DIET
Physiologist Dr. Ancel Keys noticed that the Mediterranean people living in southern Europe (Greece, Italy, Crete) had much lower risks of heart disease than Americans. He recorded what they ate and the Mediterranean diet was born.
This diet consists predominantly of fish, vegetables, fruits, seeds, beans, olive oil, nuts, cheese, yogurt and grains. Poultry and eggs eaten every two days, red meat restricted to 3 ounces per week and a glass or two of wine daily.
The similarities: Like keto, the Mediterranean diet emphasizes simple, whole foods.
The differences: The Mediterranean diet is relatively low-fat, with non-ketogenic net carbs coming from grains like bread, quinoa, brown rice, starchy fruits and vegetables.
The Pros of the Mediterranean Diet:
The easiest of the four diets outlined here
Avoids highly processed foods like paleo.
The ketogenic diet has one purpose: to induce ketosis, burning fat instead of carbs.
The other diets have their own share of health benefits, particularly the Mediterranean diet[*], and all of them help with weight loss, though only the ketogenic diet helps you induce and maintain ketosis.
The focus of these diets is to eat healthy, whole foods that are as close to nature as possible. Even without the rigorous tracking involved on keto, you still have to watch the amount of food you are consuming on these diets in order to attain the benefits.
Keto is already considered “Atkins on steroids.” If you’re eager to gain the benefits of being in ketosis, the paleo and Mediterranean diets can be customizable to induce a ketogenic state.
Simply replace all of the bread and starchy root vegetables with more oil, fatty meats and fish and low-carb nuts.
We feature all three of the above diets on Perfect Keto:
Comparing Keto vs. the Mediterranean Diet
The Ketogenic Diet vs. the Atkins Diet
Paleo vs. Ketogenic Diet
Designing a Keto Plan for Weight Loss
Using the ketogenic diet for weight loss is all about tracking and calculating:
Anything out of balance — like too much protein or excessive exercise — can do something as simple as slow your progress into ketosis, or something more grave like disrupt your health.
Your personal needs and goals determine a lot when using the ketogenic diet for weight loss. The most important step is calculating (and sticking to) your macros.
USING A KETO MACRO CALCULATOR
To calculate your macros, start with a macro calculator (Hint: we have one you can use for free).
If you use a fitness app like MyFitnessPal, you’ve already used a macro calculator, although the free version of the app only gives you a calorie budget.
In calculating your macros, you determine your intake of carbs, protein and fat according to your BMR (basal metabolic rate), activity level, body composition and weight loss goals.
Calculating your macros is essential to achieving your goals.
So what goes into calculating your macros?
#1: Your Basal Metabolic Rate (BMR)
Your BMR is the base number of calories you need to support your body’s vital functions (breathing, heart beating, digesting food) without counting the calories needed for daily activities and exercise.
Your age, gender, height and weight determine your BMR.
Weight and height: The bigger you are, the more calories you need so your organs can support you.
Age: Muscle mass goes down as you age, which can decrease your BMR.
Gender: Body composition differs between men and women.
We get a close calculation of BMR using the Harris-Benedict equation:
BMR formula for men = 66 + (6.2 x Weight in pounds) + (12.7 x Height in inches) – (6.76 x Age)
BMR formula for women = 655.1 + (4.35 x Weight in pounds) + (4.7 x Height in inches) – (4.7 x Age)
A 28-year old woman weighing 130 pounds and standing at 5’2 would calculate her BMR as:
665.1 + 565.1 + 291.4 – 131.6 = 1390 calories needed to support bodily function
A 28-year old man weighing 182 pounds and standing at 6’1 would calculate his BMR as:
66 + 1128.4 + 914.4 – 189.28 = 1919.52 calories needed to support bodily function
#2: Your Total Daily Energy Expenditure (TDEE)
Your TDEE includes all sorts of exercise, whether it’s your daily workout or physically demanding days at work or at home. This matters in calculating your calories and macros.
Use these numbers as a guide:
1.2: Little to no exercise
1.375: Light exercise, 1-3 days per week
1.55: Moderate exercise, 3-5 days per week
1.725: Hard exercise, 6-7 days per week
1.9: Very intense exercise
Which number best matches your activity level? Multiply that number by the BMR number you calculated above. The product is your total daily calorie expenditure, or total calorie burn.
For example, a woman with a BMR of 1500 who does moderate exercise would have this formula: 1500 x 1.55 to get her total daily calorie expenditure, 2,325.
She burns 2,325 calories to support her body and daily activities.
#3: Your Body Composition: Body Fat Percentage and Lean Body Mass
Your body fat percentage determines your lean body mass — the total weight of your body minus your fat mass — which in turn determines the amount of protein you need to maintain your muscles.
This is why most gyms have skinfold calipers, which are surprisingly near-accurate. You can purchase a pair online.
Other ways to measure body fat percentage are:
DEXA scan. This stands for dual-energy x-ray absorptiometry, measures bone mineral density, but can also accurately measure your body fat percentage. It’s pricey and can take up to 30 minutes, but it is the gold standard for measuring body fat percentage.
Body measurements. Apps and online tools provide body fat calculations using your height, weight and the tape measurements of your neck, waist, and hips.
Photos. Visual estimates provide a more accurate estimate than body measurements. Take a full body photo of yourself and then compare it with the photos of other people. Keep taking photos. It will come in handy later as you track your progress.
#4: Calculating Your Body Fat and Lean Body Mass
Subtract your body fat from your weight and you get your lean body mass.
Convert your body fat percentage into pounds first. For example, your body fat is 25% and you weigh 150 pounds.
150 pounds x .25 = 37.5 pounds of body fat.
Next, subtract that from your weight.
150 pounds – 37.5 pounds of fat = 112.5 pounds of lean body mass.
Save your number. You’ll use it later to calculate your protein.
#5: Your Weight Loss Goals
To achieve weight loss, your total calorie intake each day needs to be in a deficit: you consume less calories than your total daily expenditure.
A 10%-20% deficit, or even 30% if you can manage, is a good range. Just don’t go over a 30% reduction each day because it can cause long term issues.
For example, to reduce by 20%, multiply your total calorie expenditure by 0.20. Subtract that amount from your total calorie expenditure.
That is your total daily calories, the maximum amount of calories you should consume each day. Eating less than what you burn daily would burn off the weight you want to lose.
CALCULATING YOUR CARBS
On the ketogenic diet, carbohydrates make up 5%-10% of total calories on average.
For most people, that’s around 20-50 net grams per day.
Formula: (total calorie intake x % of calories from carbs) / 4
Multiply your total calories by the percentage of carbs and divide it by 4 to get grams.
For a total daily calorie intake of 2000 with the ketogenic 5% to 10% carbs, the formula would be:
2000 x 0.05 or 0.10 = 100 to 200 calories from carbs
200 / 4 = 25g to 50g of carbs each day.