Calculating Calorie Intake: Keto Diet Edition

The ketogenic diet is a popular way to lose weight, but it requires careful planning to ensure success. Eating the right amount of calories and the right proportions of fat, protein, and carbohydrates (or macronutrients) is essential. To calculate your calorie intake, you need to determine your Basal Metabolic Rate (BMR), which is the amount of energy your body spends per unit of time while resting. This can be calculated using your gender, age, height, and weight. Once you know your BMR, you can factor in your physical activity and weight goals to determine your total daily energy expenditure (TDEE) and, therefore, your ideal calorie intake.

Calculate your Basal Metabolic Rate (BMR)

To calculate your Basal Metabolic Rate (BMR), you need to know your body's weight, height, age, and sex. Your BMR is the number of calories your body uses to stay alive, including basic functions such as heart rate, blood flow, metabolism, cell function, and growth and repair. It does not include the calories needed for daily activities such as walking, moving, and exercising.

The Mifflin-St. Jeor equation is a popular way to calculate BMR/RMR quickly. The Mifflin-St. Jeor equation is considered the most accurate equation for calculating BMR, except for leaner people who know their body fat percentage, for whom the Katch-McArdle Formula may be more accurate.

The Mifflin-St. Jeor equation is as follows:

For males:

10 × weight (in kilograms) + 6.25 × height (in centimeters) – 5 × age (in years) + 5

For females:

10 × weight (in kilograms) + 6.25 × height (in centimeters) – 5 × age (in years) – 161

For example, a 35-year-old, 200-pound (90.7-kg), 6-foot (183-cm) male would have a BMR/RMR of 1,882. At rest, he will burn around 1,882 calories in a day.

A 35-year-old female who weighs 150 pounds (68 kg) and is 5 feet 7 inches (170 cm) tall will burn around 1,409 calories per day at rest.

It's important to note that your BMR is not the number of calories your body needs in a day, but only the number of calories your body needs at rest. To calculate your total daily calorie needs, you need to multiply your BMR by an activity factor.

The activity factors are as follows:

• 2: sedentary (little to no exercise)
• 375: lightly active (light exercise 1 to 3 days per week)
• 55: moderately active (moderate exercise 6 to 7 days per week)
• 725: very active (hard exercise every day or exercising twice a day)
• 9: extra active (very hard exercise, training, or a physical job)

Then, you can calculate your total daily calorie needs using this equation:

Total daily calorie needs = BMR x activity factor

While BMR calculations can provide a useful estimate, they are not 100% accurate. The Mifflin-St. Jeor equation, for instance, can be off by around 10% of your true BMR. Additionally, knowing your BMR does not paint a full picture of your health, as other factors such as muscle-to-fat mass, underlying health conditions, hormone levels, and other metrics also play a role.

Determine your Total Daily Energy Expenditure (TDEE)

To calculate your calorie intake on a keto diet, you must first determine your Total Daily Energy Expenditure (TDEE). This is the number of calories your body burns in 24 hours and is calculated by combining your Basal Metabolic Rate (BMR) with your Physical Activity Level (PAL).

Your BMR is the amount of energy you spend per unit of time while resting. In other words, it is how much energy you burn while doing absolutely nothing. This can be calculated using the Mifflin-St Jeor Formula, which takes into account your gender, age, height, and weight. Your BMR will decrease with age as your muscle mass declines, especially after turning 30.

Your PAL measures how much energy you spend daily when you are active. This can vary depending on your activity level, ranging from sedentary (little or no exercise/desk job) to an athlete (hard exercise/sports daily and/or a physical job).

Once you have determined your BMR and PAL, you can calculate your TDEE, which is the number of calories your body burns in a day. This will tell you how many calories you need to eat daily to maintain your current weight.

If your goal is to lose weight, you can create a calorie deficit by consuming less than your TDEE. A moderate calorie deficit of 10% is generally recommended for weight loss, which means consuming 10% fewer calories than your TDEE.

On the other hand, if you want to gain weight, you can create a calorie surplus by consuming more than your TDEE. A moderate calorie surplus of 10% is recommended for gradual weight gain.

Set a calorie intake goal

To set a calorie intake goal, you must first calculate your Basal Metabolic Rate (BMR), which is the amount of energy you spend per unit of time while resting. In other words, it's how much energy you burn while doing nothing. This calculation is based on your gender, age, height, and weight.

Once you have your BMR, you can determine your Total Daily Energy Expenditure (TDEE) by factoring in your physical activity level. Your TDEE is the number of calories your body burns in 24 hours.

Now that you know how many calories you burn in a day, you can set a calorie intake goal depending on whether you want to maintain, lose, or gain weight. If you want to maintain your weight, aim for a calorie intake that matches your TDEE. To lose weight, create a calorie deficit by consuming less than your TDEE. For moderate weight loss, a deficit of 10-20% is generally recommended. Conversely, to gain weight, create a calorie surplus by consuming more than your TDEE. A surplus of 10-20% is considered moderate weight gain.

It's important to note that the quality of calories matters, too. On the keto diet, your calorie intake should consist primarily of healthy fats, with moderate protein and minimal carbohydrates.

Understand the role of macronutrients

Understanding the role of macronutrients is crucial when calculating calorie intake on a keto diet. The keto diet is a high-fat, low-carbohydrate approach that aims to induce a metabolic state called ketosis, where the body uses fat instead of carbohydrates as its primary fuel source. This shift in metabolism is intended to facilitate weight loss, enhance mental clarity, and boost energy levels.

Macronutrients, or "macros," refer to the amount of protein, carbohydrates, and fat that an individual consumes and are essential for the body to function optimally. On a keto diet, the standard macro ratio consists of 5% or fewer calories from carbohydrates, 70-80% of calories from healthy fats, and 20-30% of calories from protein. This typically translates to around 25 grams of carbohydrates, 156-178 grams of fat, and 100-150 grams of protein for a 2,000-calorie diet.

Carbohydrates: Restricting carbohydrate intake is a fundamental aspect of the keto diet. By limiting carbs to just 5% to 10% of total calories, individuals can trigger ketosis, where the body burns fat for energy instead of glucose. This typically means consuming less than 50 grams of carbs per day, which can be challenging as it restricts nutrient-dense foods like fruits and whole grains.

Fats: On the keto diet, healthy fats become the primary source of energy, comprising 70% to 80% of total calories. This includes fatty cuts of meat, eggs, fatty fish, avocados, nuts, and healthy oils like olive oil and coconut oil. It is important to prioritize healthy fats and avoid excessive consumption of saturated fats, as this may increase the risk of heart disease.

Protein: While the keto diet emphasizes fat intake, protein also plays a crucial role, accounting for 20% to 30% of total calories. This equates to approximately 100-150 grams of protein per day for a 2,000-calorie diet. Adequate protein intake is essential to maintain muscle mass and support various metabolic processes in the body. It is recommended to consume a minimum of 0.8 grams of protein per pound of lean body mass, with the potential to increase this amount based on strength goals and exercise demands.

It is worth noting that the exact macro ratio may vary depending on individual factors such as age, activity level, and specific health goals. Additionally, it is always advisable to consult with a healthcare provider or registered dietitian before starting a new diet, especially one as restrictive as the keto diet.

Plan meals and track macros

Planning meals and tracking macronutrients is essential for success on a ketogenic diet. This involves eating the right amount of daily calories in the correct proportions of fat, protein, and carbohydrates. To get started, you can use a keto calculator, which will help you determine your optimal macronutrient intake based on your age, body measurements, weight goals, and physical activity level.

When planning your meals, it's important to remember that fat is your primary fuel source on the keto diet, so adequate fat intake is crucial for achieving ketosis. Protein is also important as it is the building block of human muscle mass. Eating too little protein may result in muscle mass loss, while consuming too much can lead to the excess being converted into glycogen, potentially kicking you out of ketosis. Lastly, carbohydrates should be severely limited on a ketogenic diet. While the exact amount can vary from person to person, it is generally recommended to restrict carbohydrates to 20 grams per day when starting. Once you have adapted to the keto diet, you can experiment with your carbohydrate intake to find your "carb edge".

To track your macronutrient intake, you can use a simple journal or an app like MyFitnessPal. While hitting your daily macro targets is ideal, it may not always be realistic. In such cases, you can get close to your targets by experimenting with different keto recipes and finding meals that work for you. Over time, with regular practice, planning and tracking your macros will become easier.

Additionally, when planning your meals, it's important to choose whole, unprocessed, nutrient-dense foods such as various meats, fish, eggs, poultry, and non-starchy vegetables. This approach, known as "clean keto," not only helps you stay in ketosis but also improves your overall health. While processed foods can also be part of a keto diet, they may lack nutrients and contain added sugars. Therefore, it's crucial to make informed choices and ensure that your keto journey aligns with your health and wellness goals.

Frequently asked questions