How to Calculate Keto Macros

What are macros in the keto diet plan? Macros is short for macronutrients, and the three primary macronutrients (the main groups of food that provide fuel for your body) are fats, protein, and carbs.

The key to keto is that you’re getting only a small amount of your nutrition from carbs. Even if you eat a high-fat and moderate-protein diet, if you go over your carb limit, you’ll be kicked out of ketosis. You’ll have to monitor your carb intake closely until you get used to being on a very low-carb diet and have a good sense of the amount of carbs in different foods. This will mean understanding the ratio of macros in a serving size when you eat fresh foods and always, always checking the nutrition labels when you eat anything from a package.

As you start your keto journey, it’s a good idea to get a sense of not only how many calories you should consume, but also how much of each macro — fat, protein, and carbs — you should eat throughout the day. Many people are awful at estimating the portion size or number of calories in a typical meal. Portion sizes have increased dramatically over the past few decades, with bagels getting twice as big and a standard “cup” of soda more than tripling in size! The recent decision to label calorie servings in restaurants may help this trend, but all too often this information is hidden away from consumers — to decrease the chance that they’ll make the better decision to skip the tub of popcorn with the movie.

If you grossly underestimate the number of calories — and carbs — you’re eating, you’ll keep wondering why you’re having a hard time losing extra weight. Being informed and learning how to accurately estimate the number of calories in your go-to meals, as well as the “innocent” snacks that you may sometimes forget to count, will really help you gain a handle on your target food intake.

After you’ve got a good sense of how many calories you’re actually eating, it’s time to check out some of the calculators available on the web to figure out how many you should be eating.

If you’re eager to figure this out now, we’ve provided you with the tools to help you “guestimate” these values on a daily basis and walk you through how to do this step by step.

How to determine the total calories you need, your resting metabolic rate

Your total daily calories, or resting caloric intake, is the number of calories your body needs each day. This number is also called resting metabolic rate (RMR), and it’s essentially the amount of energy you need every day to carry out the essential functions of life — building up and breaking down the tissues of your body, breathing, and resting quietly.

Your RMR depends on a host of factors, including weight, lean body mass, age, activity level, gender, and more.

If you’ve wondered why a friend can eat whatever she wants and never gain an ounce, it could be that she’s naturally blessed with a faster metabolism from her parents, or it could be related to an overactive thyroid gland. The thyroid produces thyroxin, which is the hormone that most tightly influences metabolic rate. Too much of it can lead to weight loss, while hypothyroidism — a more common issue — can lead to weight gain.

On the other hand, if someone gains weight by merely glancing at a cookie, it could be due to one of several reasons. He may be shorter (taller people tend to have higher caloric needs), already overweight (fat is less metabolically active than muscle), or spend his days in a climate-controlled environment (exposure to both cold and heat can jump-start RMR because your body has to do the work to regulate your body temperature, rather than the thermostat).

What you eat also affects your metabolism. Eating and digesting your food requires energy and creates heat. The opposite, starvation diets, actually slow your metabolism down as your body tries to conserve what energy you have. You can drop your metabolism by as much as 30 percent if you slash your calories too quickly, making it difficult to lose the extra pounds you’re trying to shed. Interestingly, as we mention in Part 1, by optimizing your body’s hormonal balance, keto may derail this tendency to hold onto excess weight even as you cut back on calories.

There are two main ways to determine your RMR:

• Indirect calorimetry: This is the most accurate way to assess your RMR, but it’s also more cumbersome and expensive. It’s a useful tool if you want the most effective and unique nutritional plan to help you achieve your dream weight.

Indirect calorimetry measures the amount of heat you produce by determining how much gas (carbon dioxide and nitrogen) you exhale. Because these gases are the end products of the majority of metabolism, it gives a very accurate measurement of how much energy you use in a given period.

There are several methods to measure your exhaled gases, but they all require purchasing expensive equipment or setting up an appointment with a personal trainer, nutritionist, or doctor. A commonly used device, BodyGem, is a handheld machine that requires about ten minutes to determine your RMR accurately. Older indirect calorimeters required face masks or lying quietly in a closed chamber in a laboratory. Obtaining this result will run you about $50 to $75.

• RMR calculators: These calculators use complicated formulas that take into account several criteria to come up with a unique number of calories you should consume per day. There are several calculators available to estimate your basal calorie intake, but the accuracy of these calculators can vary by as much as 400 calories per day — almost enough to cause a weight change of a pound per week! The various RMR calculators are more likely to cause a higher degree of inaccuracy in people who are overweight. This happens because most of the formulas use your current weight as a significant part of the calculation. Excess body weight is often fat, which is less metabolically active than muscle and will, therefore, overestimate how many calories you actually need if you’re overweight.

RMR calculators aren’t as precise as indirect calorimetry, so if you really want an accurate result or you’re overweight and serious about weight loss, it might be useful to get the indirect calorimetry done for the best results.

If you’re okay with a tiny amount of guesswork, the tried-and-true RMR calculator that many dietitians and nutritionists have used for years is the Mifflin–St. Jeor formula. It’s the most accurate calculator with a difference from indirect calorimetry of only about 20 calories per day for a person with a healthy body weight. Similar to other calculators, this number rises in an overweight individual and can be as much as a 150-calorie difference.

Beware that both indirect calorimeters and RMR calorimeters only provide you with the minimal number of calories you need, and they don’t account for more activity than would happen if you were lying in bed all day binge-watching Netflix. Physical activity is the best thing you can do to increase your daily caloric intake, and you’ll need to remember to modify your total caloric intake based on how much activity you do in a given day.

After you’ve calculated your RMR, you’ll need to figure out your total daily energy expenditure (TDEE). This number takes into account the amount of activity you do. Use one of the following numbers, depending on your level of daily activity:

• 2: You have an office job and spend very little time engaging in any physical activity.
• 375: You’re slightly more active. This generally means doing some walking or household work up to three days a week.
• 55: You engage in moderate levels of activity. People in this category exercise at a higher level between three and five days a week.
• 725: You’re very active. You enjoy significant exercise, like CrossFit, swimming, or some form of martial arts, six or seven days each week.
• 9: You’re close to an Olympic-level athlete. You can use this number if you have a very physically demanding day job, or you engage in professional-level sports regularly.

If you’re trying to lose or gain weight, of course, you need to adjust these numbers to reflect your goal. As a general rule, although there is some variety to these results, you need to slash (or add) about 250 calories per day to lose (or gain) half a pound per week. Bump this up to 500 calories a day if you’d like to move the scale about one pound in a week. The basic math for weight loss takes your RMR, adds in the amount of physical activity you do, and then matches those needs with what you eat. If you have an excess, you’ll gain weight; if you have a deficit, you’re primed to lose weight.

Here is the basic Mifflin–St. Jeor formula. It’s different depending on your gender:

• For men: (10 × weight in kilograms) + (6.25 × height in centimeters) – (5 × age in years) + 5
• For women: (10 × weight in kilograms) + (6.25 × height in centimeters) – (5 × age in years) – 161

To convert pounds to kilograms, divide your weight in pounds by 2.2. To convert inches to centimeters, multiply your height in inches by 2.54.

Let’s take the example of a man who is 30 years old, weighs 150 pounds, and is 5 feet 8 inches tall. Assume he wants to maintain his weight and he’s working a desk job with little physical activity. Here’s how to calculate his total caloric intake:

1. Convert his weight (150 pounds) to kilograms. That’s 150 / 2.2 = 68.18 kilograms.
2. Convert his height (5 feet 8 inches) to centimeters. First, you have to convert his height to inches. There are 12 inches in 1 foot, so he’s 60 inches + 8 inches = 68 inches tall. Now 68 × 2.54 = 172.72 centimeters.
3. Multiply his weight in kilograms by 10. That’s 68.18 × 10 = 681.8.
4. Multiply his height in centimeters by 6.25. That’s 172.72 × 6.25 = 1,079.5.
5. Multiply his age in years by 5. That’s 30 × 5 = 150.
6. Add the amounts from Step 3 and Step 4, subtract the amount from Step 5, and add 5. That’s 681.8 + 1,079.5 – 150 + 5 = 1,616.3 calories. That’s his RMR.
7. To get his TDEE, multiply his RMR by 1.2, which reflects his activity level. That’s 1616.3 × 1.2 = 1,939.56, or rounding up, 1,940 calories per day.

If the idea of doing all this math sounds like torture to you, check out this free online calculator.

Keto macros: how many fat grams do you need

After figuring out the number of calories you need, it’s time to take a look at how many grams of each type of macro you should be eating per day. To figure this out, you’ll need to multiply your total calories by the fraction the macro plays in your daily diet. For example, if you’re consuming 2,000 calories per day and you want to go with 75 percent from fat, 20 percent from protein, and 5 percent from carbs, you’d perform the following calculations:

• 2,000 × 0.75 = 1,500 calories from fat per day
• 2,000 × 0.20 = 400 calories from protein per day
• 2,000 × 0.05 = 100 calories from carbs per day

Unfortunately, most nutrition labels don’t break down your macros into calories from each group; they give you the total number of calories, and then break each individual nutrient into grams. That means the next step is finding out how many grams of each macro you can have.

Your percentage of fat and protein will slightly change if you’re on the standard ketogenic diet versus the protein ketogenic diet. Both protein and carbs provide four calories per gram, while fat contains nine calories, so divide by the appropriate number to get accurate results.

As the majority of your caloric intake, fat should be about 75 percent of your total intake on keto. Some people may go as high as 80 percent (strict keto for medical conditions like epilepsy) or drop down to 65 percent (if they’re on the high-protein keto diet). Let’s continue using the example above:

1,500 / 9 = 167 grams

In this example, you need to eat about 167 grams of fat per day. You’ll need to adjust this depending on the type of keto diet you’re following. You divide by nine because there are nine calories for every fat gram, compared to four each for the other two macros.

Keto macros: how many protein grams do you need

To calculate calories for moderate protein (for maintenance and weight loss, not building muscle) intake, the formula looks like this:

400 / 4 = 100 grams

This example, for the standard ketogenic diet, will require about 100 grams of protein. If you’re trying to build muscle, the general rule is to take in 1 gram of protein per pound of body weight, although this would decrease if you’re significantly overweight.

If your body fat percentage is 30 percent or higher for women or 25 percent or higher for men, you should focus on losing excess fat before really attempting to build muscle. This isn’t to say that you can’t go to the gym before you hit a certain body fat percentage — not at all! However, bulking and building muscle requires excess protein, which means upping your overall caloric intake while decreasing the amount of fat you’re eating. It can get very complicated to try to balance having enough excess calories to build muscle while cutting them to lose fat. You can successfully combine these two efforts, but it’s somewhat difficult. If you’re just starting out, focus on either fat loss or muscle building.

Keto macros: how many carb grams do you need

The macro with the least amount of calories will be carbs, and it’s calculated by the following formula (again, using the example from earlier):

100 / 4 = 25 grams

Generally, eating around 25 grams of carbs is a good starting point when you decide to transition to the keto diet. However, everyone will have a slightly different carb allotment. Some people will maintain ketosis at a little over 50 grams of carbs per day while others have to really slash their carbs to stay in ketosis. Over time, as you understand when your body is in ketosis (or with the aid of urine strips or other tests), you may be able to modify your carb allotment. Also, if you’re on the targeted keto diet and you add some extra carbs around the time of your intense workout, you’ll be able to increase this number. Remember that the longer you’re on keto, the more efficiently your body uses the process, and you can generally add in more carbs over time.

A critical part of success on the keto diet is being aware of how many calories you need each day, as well as where you need to get your calories. Pull out your dusty calculator or head over to a good calorie counter to keep yourself on track.