Whenever I start working with a new client whose primary goal is weight loss, I assign her the task of food tracking. Before I can suggest changes to her diet, I need to know what she’s currently eating.
Most of my clients use online food tracking software, with MyFitnessPal being the most popular choice, by far. Because MFP also allows users to ‘earn’ extra calories via exercise, the question ‘Should I track the calories burned during exercise?’ inevitably arises.
The question is a good one because weight loss depends on creating a net caloric deficit; to lose weight, one must consume fewer calories than are expended during the day. (Typically, a 500 calorie a day calorie deficit will result in a one pound weekly weight loss).
In a perfect world, where accurate measures of caloric intake and expenditure are available to all, my answer would be;
Yes! Track your workouts with as much care as you track your food and adjust your daily net calorie intake in a way that’s sustainable, well above your basal metabolic rate and on track for a 1-2 pound per week weight loss.
Because we live in a world full of imprecise estimates and frequently invalid assumptions, however, I typically recommend that newcomers to food tracking focus solely on the ‘calories consumed’ part of the equation (at least until we’ve obtained enough information to create a weight loss plan).
[If food tracking makes you crazy or you aren’t sure how to get started, click through to read last week’s post “Food Tracking Tips: Lose Weight Without Losing Your Sanity”]
Why? People have a tendency to underestimate the number of calories they consume (think that was really just a tablespoon of peanut butter? did you measure it? if not, I bet it was more…) and over-estimate the number of calories burned during exercise (especially if they use the estimates displayed on most cardio machines or reported in standard ‘calories burned during exercise’ tables).
Once food tracking is well-established (and perhaps only used periodically to ‘check-in’) and exercise has become a regular part of a client’s day, the question of whether to measure and incorporate calories burned during exercise into the daily energy plan becomes relevant for two reasons;
- to ensure that she’s not eating fewer calories than required by her body for daily maintenance (known as ‘basal metabolic rate’ or BMR) and
- to determine how many calories can actually be consumed while still losing weight.
The first is important because long-term under-eating tends to undermine weight loss via it’s lowering of the body’s rate of calorie burn. Eating below BMR teaches the body to conserve energy and be all-too-eager to store excess calories as fat (when one inevitably returns to a more ‘normal’ pattern of eating).
The second is important because cutting calories is challenging enough without feeling ‘hangry’. If exercise allows you to consume an extra 200 calories a day and still lose weight in a safe and sustained manner, why deprive yourself?
The challenge now? To actually figure out how many extra calories you can eat in a day, as a consequence of exercise.
Many users of online trackers simply use the options provided to them by the tool itself. For example, MyFitnessPal allows you to choose from a list of exercise activities (both strength and cardiovascular), indicate how long you performed the activity and provide details about reps, sets and loads (for strength workouts) before giving you an estimate of calories burned during exercise.
There are several difficulties with this approach:
- estimates are just estimates and may not apply to you. Online calorie trackers typically consider only your weight and the duration of an activity to generate an estimate of caloric expenditure. This estimate is based on the average number of calories burned by thousands of other similar-weight people performing the same activity for the same duration. Without knowing the error of the estimate (a statistical term that should be provided for all averages…), you can’t know how wildly your actual calorie expenditure might differ from the published value.
- Exercise intensity is rarely considered and when it is, it’s measured subjectively. Most of the activities included have generic, intensity-free labels; ‘Running’, ‘Yoga’, ‘Spinning’ (and my personal favourite, ‘Wii Bowling’). When intensity-modifiers are included, it’s up to the user to decide whether their activity was ‘moderate’ or ‘vigorous’. As a Bootcamp instructor, I know that one person’s ‘vigorous’ is another person’s ‘light’ (especially when it comes to Burpees and Box jumps…). And I bet that my definition of ‘light housekeeping’ is substantially ‘lighter’ than yours 😉
- calories burned during strength training depend on more than just sets, reps and load. Depending on the amount of rest time between sets, the tempo of the lifts and whether the workout has triggered an ‘afterburn’ effect (that is, whether they’ll continue to burn calories at a rate higher than usual for the remainder of the day), strength training can be more or less energetically costly than indicated by published tables and online calculators.
Rather than have my clients (inaccurately) estimate the number of calories they burn during each and every workout (and potentially undermine their weight loss goals), I prefer to individually tailor their daily recommended calorie intake to their weekly workout frequency and intensity.
I do this by;
1. calculating BMR (you can calculate your own here >> MyFitnessPal’s BMR calculator; MFP uses the Mifflin-St. Jeor equations to estimate BMR which is believed to be more accurate than the more commonly used Harris-Benedict equation)
2. calculating daily caloric needs based on weekly workout frequency and intensity (you can calculate your own here >> ACE’s Daily Caloric Requirement calculator. I typically generate two values for this number; one using the client’s reported weekly workout frequency and intensity and the second using the multiplier for a slightly less intense workout week, just in case 😉 ).
3. comparing both numbers and choosing a value somewhere between the client’s BMR and Daily Caloric requirement that’s in line with their weight loss goals. I have my client enter this number in MFP (or whatever tracker they’re using), over-riding the program’s calculated daily calorie goal (not sure how to do this? see the imbedded video at the bottom of the post for a quick tutorial). We then work towards this target for a few weeks, paying attention to energy levels, feelings of hunger and satiety, quality of sleep and measurable weight loss. If need be, we alter it by 100 calories or so and repeat.
While this approach isn’t error-free, it fits nicely with my general approach to fitness and nutrition;
Figure out the smallest possible change you can make and still see results.
Not to mention all the time it’ll free up by saving you from having to enter your daily workouts in your food tracking software!
Do you account for calories burned during exercise in your food tracker?
Do you find that knowing how many calories you burned during exercise tempts you to ‘eat back your calories plus more’?
Not sure how to change your daily goals in MyFitnessPal? Watch the short clip below (and note that I’ve also indicated a way to change macronutrients too), then ‘Subscribe’ to my YouTube channel to stay up-to-date on my video offerings!