Have you ever logged every morsel of food and workout and still didn’t lose any weight or possibly gained weight?
Many people use trackers to log their food and exercise, but do they really work?
Even though I encourage clients to track their food, here is the problem with fitness trackers.
The problem with net calories
Here’s how fitness trackers work: You start every day with a certain number of calories to spend. That number is based on your height, weight, age, sex, activity level, and goals.
Calories are subtracted from your balance as you log your meals into MyFitnessPal, or whatever tracker you are using. Let’s say it’s 5 pm, and I’m down to my last 400 calories; I can go for a run, log it into the app, and now I’ve got 840 calories to spend on dinner! How awesome is that?
The general principle here is sound: The more you move, the more you can eat. However, these “net calorie” calculations are inaccurate and misleading—and because of it, people are eating too many calories.
Why You shouldn’t Log Your Exercise
Although diet tracking apps can help you get an accurate picture of your calorie intake, they are less reliable in determining how many calories you burn. Here’s why:
Mistake #1: Your baseline may be too high. To calculate your baseline calorie requirements, you indicate your activity level: sedentary, lightly active, moderately active, or very active. This does not refer to how much you exercise; this is just about your daily movements.
Most people overestimate their activity level one or two categories higher. Unless you dig trenches eight hours a day, your lifestyle probably does not qualify as “very active.”
If you use a wearable fitness tracker like a Fitbit or Apple Watch, you can use that to help you select the proper category for your lifestyle. Here’s a cheat sheet:
- Fewer than 2,000 steps a day is Sedentary.
- Fewer than 10,000 steps or about four miles a day is Lightly Active.
- 10,000 to 23,000 steps or four to 10 miles a day is considered Active.
- More than 23,000 steps or 10 miles a day is Highly Active.
If you walk or run for exercise, you can count those steps and/or miles toward your baseline activity level if you want, but then you can’t enter them again as exercise. They’ve already been counted.
Mistake #2: The calories burned from working out are often overestimated. Most diet tracking apps give you a place to manually log your workouts, such as a spinning class, HIIT, or weight training. Alternatively, there are wearable devices that sense your movement and changes in your heart rate. Either way, you’re most likely not burning as many calories as your app, tracker, or cardio machine says. Most fitness trackers are inaccurate when it comes to estimating calories burned from exercise. Even an Apple Watch has been shown to overestimate calories burned by 40%!!! This is why if you eat back your workout calories, you can very easily wipe out your calorie deficit and stall your progress.
Also, the more you do the same exercise, the more efficient your body becomes at performing that motion. As a result, you burn fewer calories. The first time I run an eight-minute mile, I’m probably going to burn more calories than the 100th time I run an eight-minute mile.
Mistake #3: You could be counting some of those calories twice. If I spend an hour folding clothes and vacuuming my house, I’ll burn about 100 calories. Those non-active calories are already accounted for in my daily calorie allowance.
One of my clients told me she burns 2,500 calories a day but only eats 2,000. She couldn’t figure out why she was gaining weight. Sure enough, she was eating back her non-active calories. She logged every non-active activity of her day: making beds, folding laundry, stretching, walking the dog, grocery shopping, gardening, cleaning, and so on. According to her tracker, all those activities burned an extra 1,000 calories a day, giving her a total “net calorie” allowance of 2,500 calories a day. She figured she could eat 2,000 calories a day and still lose weight.
In reality, all of her little “activities” probably burned a couple of hundred calories above her baseline. No wonder she wasn’t losing weight.
- Don’t eat back your calories burned.
- Fitness trackers WAY overestimate calories burned.
- Activity trackers can be a great way to track your steps, heart rate and encourage daily activity.
- Stop thinking of exercise to burn calories or earn food and focus on the many other benefits it provides instead. If you need help with your workouts or diet, check out my Customized Meal Plan or FIT12 Program.
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