Macros Math: Low Carb Vs Keto Diet

The ketogenic diet is a low-carb, high-fat diet that restricts carbohydrates and replaces them with fat, putting your body in a metabolic state called ketosis. To calculate your macronutrients, or macros, for a low-carb or keto diet, you need to take into account your body measurements, weight loss goals, physical activity, and age. There are many keto macro calculators available online that can help you figure out how much fat, protein, and carbohydrates you should be consuming each day. These calculators use formulas like the Mifflin-St. Jeor equation to determine your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE). By entering your information into a keto calculator, you can get a personalised macro plan that tells you exactly how many grams of net carbs, fat, and protein you need to consume each day to reach your goals.

How to calculate your basal metabolic rate (BMR)

To calculate your basal metabolic rate (BMR), you can use one of the following formulas. Note that BMR is the amount of energy expended while at rest in a neutrally temperate environment, and in a post-absorptive state (meaning that the digestive system is inactive, which requires about 12 hours of fasting).

Mifflin-St Jeor Equation:

For men:

BMR = 10W + 6.25H - 5A + 5

BMR = 10W + 6.25H - 5A - 161

For women:

BMR = 10W + 6.25H - 5A - 161

Revised Harris-Benedict Equation:

BMR = 13.397W + 4.799H - 5.677A + 88.362

BMR = 9.247W + 3.098H - 4.330A + 447.593

Katch-McArdle Formula:

BMR = 370 + 21.6(1 - F)W

In these formulas:

• W is body weight in kg
• H is body height in cm
• A is age
• F is body fat in percentage

While the Mifflin-St Jeor Equation is considered the most accurate formula for calculating BMR, the Katch-McArdle Formula can be more accurate for people who are leaner and know their body fat percentage.

How to calculate your total daily energy expenditure (TDEE)

To calculate your Total Daily Energy Expenditure (TDEE), you need to determine how many calories you burn in a day, taking into account your daily activities and exercise. TDEE is calculated by first figuring out your Basal Metabolic Rate (BMR), then multiplying that value by an activity multiplier.

Your BMR is the number of calories your body burns at rest, or the minimum energy required to maintain vital organs. It is calculated based on physical characteristics such as age, gender, height, and weight. There are several equations for estimating BMR, including the Mifflin St-Jeor Equation, Harris-Benedict equation, and Katch-McArdle Formula.

Once you have calculated your BMR, you then multiply it by an activity level factor, which takes into account the amount and intensity of exercise you engage in, as well as other daily activities. This could include activities such as walking, standing, fidgeting, and maintaining posture, which are categorised as non-exercise activity thermogenesis (NEAT).

You can also take into account the thermic effect of food (TEF), which is the amount of energy required by the body to process and use food. This is sometimes estimated as 10% of food energy intake, but can vary depending on the type of food consumed.

By calculating your TDEE, you can gain a better understanding of your total calorie expenditure, which is useful for tailoring your calorie intake according to your fitness and weight goals.

How to calculate your lean body mass

Lean body mass is the weight of your body minus the weight of body fat. It includes the combined weight of bones, muscles, water, ligaments, tendons, and internal organs.

There are multiple ways to calculate your lean body mass. One way is to use a lean body mass calculator, which will ask for your weight, height, gender, and age. The calculator will then compute your lean body mass based on different formulas.

Another way to calculate your lean body mass is by using the following formula:

Lean Body Mass = Body Weight - (Body Weight x Body Fat %)

First, measure your body weight. Then, multiply your body weight by your body fat percentage. Finally, subtract this result from your body weight.

For example, if you weigh 150 pounds and have a body fat percentage of 20%, your lean body mass would be calculated as follows:

Lean Body Mass = 150 pounds - (150 pounds x 20%)

Lean Body Mass = 150 pounds - 30 pounds

Lean Body Mass = 120 pounds

It's important to know your lean body mass, especially if you're trying to lose weight. Monitoring your lean body mass can help you track how much muscle you're losing. Additionally, knowing your lean body mass can help you decide how much fat you should lose and what your body fat percentage will be after that.

How to calculate your net carbs

To calculate your net carbs, you need to know the total amount of carbohydrates in the food you are eating. This information is usually available on the nutrition label.

Once you know the total amount of carbs, you can calculate the net carbs by subtracting the amount of fibre and sugar alcohols. Fibre is a type of complex carb that the body cannot fully digest. Sugar alcohols are used to add sweetness to low-carb foods and are processed by the body in a similar way to fibre.

The formula for calculating net carbs is: Total Carbs (g) – Fibre (g) – Sugar Alcohols (g) = Net Carbs.

However, there are different types of sugar alcohols, and some of them are only partially absorbed by the body. Erythritol, for example, is not digested by the body at all, so you can subtract its total value from the total carbs. For other types of sugar alcohols, such as maltitol, sorbitol, isomalt and glycerin, you should only subtract half of their total value from the total carbs.

Calculating net carbs can be beneficial for people with diabetes, as it helps them track their fibre intake and balance their medication with carb intake. It can also increase the number of food choices available, as many fruits and vegetables are rich in fibre and contribute fewer carbs. However, counting net carbs may also lead to increased consumption of sugar-free treats, which are not necessarily carb-free. It is important to note that not all experts agree on the concept of net carbs, and it is always recommended to consult a doctor or dietitian before starting a new diet.

How to calculate your calorie deficit or surplus

To calculate your calorie deficit or surplus, you need to find out your total daily energy expenditure (TDEE). This is the number of calories your body burns in 24 hours and is calculated by adding your basal metabolic rate (BMR) to your physical activity level.

Your BMR is the number of calories you burn for basic, life-sustaining functions. This is calculated using the Mifflin-St Jeor equation, which takes into account your gender, age, height, and weight. Your physical activity level (PAL) measures how much energy you spend daily when active.

Once you have your TDEE, you can calculate your calorie deficit or surplus. A calorie deficit means consuming fewer calories than your TDEE, and a calorie surplus means consuming more. For example, if your TDEE is 2,000 calories, a 10% calorie deficit would mean consuming 1,800 calories per day, and a 10% calorie surplus would mean consuming 2,200 calories per day.

It is recommended that you stay within a moderate calorie deficit or surplus of 10-20% for safe and sustainable weight loss or gain.

Frequently asked questions