Flexible Dieting: Determining Your Daily Calorie Needs for Weight Loss

Get out the calculator, because today’s blog post is a work session! If you ever wondered how many calories you should be eating in a day, we’re going to give you the Registered Dietitian’s insider scoop of how to calculate that number, and what exactly to take into consideration before setting it as your daily calorie goal.

Before we dive into the math, let’s understand the two main approaches to go about healthy eating and weight management from a dietetic perspective: a diet approach (for example: counting calories) and a non-diet approach (for example: intuitive eating). Each approach has its benefits and challenges and which approach you use depends on the individual. For example, if you hate reading labels or have a history of disordered eating tendencies, an intuitive eating approach might be better suited for you. On the other hand, if you geek out about the numbers and feel positively motivated by counting calories, an approach called flexible dieting might fit your preferences. Today we are going to dive into flexible dieting to understand what it is and how to determine your daily calorie needs! 

Flexible Dieting and Macronutrients

First, what is flexible dieting? Flexible dieting is a sustainable and objective weight management method that creates healthier habits by tracking calories and macronutrients to ensure a consistent daily intake to promote weight loss, maintenance, or weight gain, depending on individual goals. Flexible dieting provides an objective way to ensure you are eating in a calorie deficit or surplus (depending on your goals), while offering the flexibility and educational tools needed for life-long sustainability and awareness. Simply put, if you put in the consistency and accuracy, you can almost perfectly predict weight loss, gain, or maintenance down to a science. 

The first step to flexible dieting is determining your goals and macronutrients. Macronutrients, or macros for short, are the proteins, carbohydrates, and fats that make up our food. You may have seen others tout online or irl that they are counting macros to lose weight, meaning they have a specific number of carbs, proteins, and fats they are trying to consume each day. As imagined, this can be extremely difficult to maintain consistency and balance a normal life while trying to perfectly consume a set number of macros each day.

Enter: flexible dieting. Research has shown that when calories and protein are equated, carbs and fats can be interchangeable - meaning we do not have to eat the same number of carbs and fats each day if we are being consistent and eating the same calories and protein each day. The goal is 90% accuracy, 100% of the time. 

Determining Your Goals

Now, let’s determine your goals! We recommend taking out a notebook and answering these questions: 

• What are your short-term goals? What are your long-term goals?

• Are you looking for weight loss or weight gain? Why? This is huge - be reflective about the why behind your goals. Many times we want weight loss, but it's actually tied to a greater self-confidence issue - weight loss won't actually solve that problem. Getting clear on your why will also help you continue to push forward, even when things get tough and you don't feel like being consistent anymore.

• What is your current daily intake? Are your daily calories already very low? If so, you may need to reverse dieting in order to prepare your body for a healthy weight loss phase.

• Are your goals appropriate? Are they realistic? Avoid sacrificing quality of life just to hit a very low number on the scale. Try taking your original weight loss goal and adding 7lbs to it. Can you live with this number? Our bet is yes. Remember, you want something realistic and feasible for long-term sustainability and metabolic health.

The Math

Now that you have identified your goals, let’s determine your macronutrients. To help make this easier, we’ll use an example at each step, so use a pen, paper, and calculator to follow along:

Step 1: Write down your age, height (in cm), & weight (in kg):

• Age = 27

• Height (convert to cm) = 5'3" = 63 in. x 2.54 = 160 cm

• Weight (convert to kg) = 148 lbs / 2.2 = 67.3 kg

Step 2: Calculate your Basal Metabolic Rate (BMR - the calories you burn everyday at complete rest) using the Mifflin St Jeor (MSJ) Equation based on your gender:

• Men: 10 x weight (kg) + 6.25 x height (cm) - 5 x age (years) + 5

• Women: 10 x weight (kg) + 6.25 x height (cm) - 5 x age (years) - 161 

Step 3: Plug & play - follow the below example very carefully (the equation can easily get messed up if you ignore the order of operations). For the below example, we will use the MSJ for women, so please make sure you use the correct equation for your gender:

• MSJ Women = 10 x weight (kg) + 6.25 x height (cm) -5 x age (y) - 161

• BMR = (10 x 67.3kg) + (6.25 x 160cm) - (5 x 27) - 161

• Note - complete this section as two halves

  • BMR = (673 + 1,000) - (135 - 161) = 1,673 - 296

  • BMR = 1,377 kcals/day 

Step 4: Calculate your Total Daily Energy Expenditure (TDEE - the amount of calories you need to consume based on your activity level, otherwise known as your maintenance calories) by multiplying your BMR by an Activity Factor. Choose the activity factor below that is most accurate for your lifestyle:

• BMR X 1.2: sedentary (no exercise, bed-ridden)

• BMR X 1.375: slightly active (exercise 1-3 days/week)

• BMR X 1.55: moderately active (exercise 3-5 days/week)

• BMR X 1.725: very active (exercise 6-7 days/week)

• BMR X 1.9: extra active (very hard exercise + physical job or double training sessions)

• Example: TDEE = 1,377 kcals (BMR) x 1.55 (AF) = 2,134 kcals/day 

Note - this number is your BMR; the following steps will help you determine what your starting calories should be. While steps one through four can be completed using an online BMR calculator, steps five and six will require some contextual thinking. 

Step 5: Based on your goal, implement a calorie deficit or surplus:

• For weight loss: 

  • There are 3500 kcals per pound of body weight; therefore, to lose 1lb per week, you would need to be in a total deficit of 3500 kcals per week. To identify your daily calorie deficit, divide 3500 kcals by 7 days = 500 kcal deficit per day.

  • Using our previous example, to lose 1lb per week, subtract 500 calories from the TDEE to obtain your calorie goal:

    • 2,134 kcals - 500 kcal deficit = 1,634 kcals/day

      
      

• For weight maintenance:

  • Your calorie goal is the previously calculated TDEE = 2,134 kcals/day

    
    

• For weight gain:

  • Add 500 calories to the previously calculated TDEE:

  • 2,134 kcals + 500 kcal surplus = 2,634 kcals/day

Step 6: Set your protein goal!

The final step in determining your macros is setting your protein goal. Protein recommendations vary widely, anywhere from 0.8-1 g/kg for the general population and up to 1.5-2.5 g/kg for those who are active. Protein recommendations are heavily dependent upon activity, goals, body composition, and overall caloric intake.

That being said, the easiest way to find your protein goal is by using a percentage of your calories:

• For those who are slightly active = 20% of total calories

• For those who are moderately-very active = 25% of total calories

• For those who are extra active = 30% of total calories

MOST people do great with a 20% protein goal, some struggle trying to hit this number - use your best judgement. It's important to choose a goal that you will meet every single day.

Ready for one last math equation?

• 1,634 kcals/day x .20 (or 20%) = 326.8 calories / 4 kcals per gram of protein

• = 81.7 grams of protein daily

The Most Important Takeaway

Now that we went through the math, there’s one more thing you must take into account before starting to eat at your designated calorie goal - your current intake. This is where most people fail. Understand this very clearly - the equation we just did is only a predictive equation. Meaning, it does not take into account your metabolism and current intake!

Just because an equation gives you your maintenance calories, doesn’t mean that will magically allow you to maintain your weight. A 6’5” 240lb man’s maintenance calories might be 3200 calories per day, but if he has been eating at 2500 calories every day, then consuming 3200 calories daily will most certainly put him in a caloric surplus and cause him to gain weight. In this scenario, 3200 calories is more of a potential based off his height, weight, and activity level.

Best practice: track your calories for two weeks straight, without trying to hit a specific number on your tracker! We recommend adjusting all your goals to zero, so that you are not subconsciously influenced to hit a certain threshold. The point of this is to figure out what calorie range is supporting your current weight, then from there dropping or increasing your total calories depending on your goals.

For example, if you track for two weeks, take the average, and find out you are eating 2500 calories on average each day and would like to lose weight, then implementing a moderate 250 calorie deficit down to 2250 calories would be a great place to start! Remember two very important concepts: 1) the number you calculate is just a number - it has little to do with your actual intake, which is most important when setting a calorie/protein goal. And 2) you always want to diet on the most amount of calories possible, in order to save room for future calorie drops. For sustainable weight loss, slow and steady is the name of the game.

For more information, check out our e-book, The Ultimate Guide to Flexible Dieting, which will bring you through the step by step process of flexible dieting with all of the registered dietitian insider tips (how to track, tracking best practices, eating out, tracking alcohol, making adjustments, & more). We highly recommend seeking out the advice of a Registered Dietitian to help manage and oversee your diet for maximal success. As always, the information in this post is for informational purposes only. 

Disclaimer: The information provided in this post is for informational purposes only. Any changes to your nutrition & health should be supervised by a registered dietitian or physician.