We need calories to fuel our body on a daily basis, however, we do not need the same amount everyday. Depending on your activities throughout the day, your calorie needs may increase or decrease. Unless you are consistent in your everyday activities, your calorie intake should fluctuate with each day.

The Metabolism

Your metabolism is responsible for breaking down food into energy that then is used for daily functions, extra activities, or is stored for a low-calorie day. 

Your basal metabolic rate, or BMR, is the energy needed for daily essential functions such as breathing, blood circulating, cell turnover, protein synthesis, etc. Your BMR stays constant day after day unless you are sick or injured.

Your total daily energy expenditure, or TDEE, factors in your daily activities (walking, folding laundry, going for a run) and the energy needed to fuel these activities. It’s these daily activities that can change your daily calorie needs, sometimes drastically. 

You can determine your BMR and TDEE with online calculators, however, not all equations are accurate and some are for specific situations. The Mifflin St. Jeor equation is one of the most trusted equations for the majority of people currently available. 

Calculating your BMR is a simple task, however, calculating your TDEE can get a little more confusing. This is because your TDEE is based on your daily activities and you are essentially guessing your activity level for every day. The majority of people tend to overestimate their actual activity levels resulting in artificially higher calorie needs. 

Once you have your TDEE calculated you can apply your goals (weight loss, weight gain, weight maintenance) to get your actual daily calories you need to achieve your goal.

A dietitian can help determine what your actual needs may be after completing a thorough assessment of your life and daily activities. 

Modulating your intake

 As I mentioned before, most people are not equally active every single day. Some days you may go for a run or walk while other days you may barely move at all. Just think of the day you may have been stuck at your desk, then your car, and finally spending the evening on your couch. 

Each day will have an impact on your TDEE and depending on how drastically different your activity levels are, your daily needs can change quite drastically. Take for example the prior example of running 3 miles one day and sitting all day the next. On the day you went running, your TDEE can be 300-500 calories higher for that day. 

If you based your daily calories on this activity level, you may be over eating 500 calories on your low activity days which is enough to cause weight gain or stall your weight loss! This example makes it easy to see why you need to modulate your daily calorie intake to reflect your daily activities. 

A TDEE range can help determine your minimum and maximum daily calories based on your likely activities. This can help you quickly to decide how many calories you will need that day. 

Think of a day you started your day with best intentions to go to the gym after work and based your day's calorie needs assuming you’ll be more active only to decide you were too tired after work.. You can quickly adjust your remaining meals to reflect this decrease in your activity level. 

You can also use a wearable device (Fitbit, Apple watch, etc.) to see your daily calories burned. This can help you adjust your daily intake and understand how your activity level can impact your TDEE. Be aware that calorie counts found on cardio equipment are generalized and can be drastically different then your actual calories burned.

The Key takeaway

Although your BMR is static and takes a long time to change, your TDEE can vary daily. This is based on the activities you perform throughout each day. 

These changes often can be drastic enough to keep you from achieving your weight loss, weight gain, or weight maintenance goals.

Modulating your daily calorie intake based on your daily activities is an easy way to prevent over or under eating. 

If you want help determining your TDEE range and how to implement calorie modulation into your lifestyle, send me an email at dietitian2go@gmail.comor schedule a virtual visit with me.

Written by: Adam Skowyra MPPD, RDN, LD