RACHEL MARTIN, HOST:
All right. We all know exercise is great for your health. But if you are looking to lose weight, you should know this. Your diet ultimately matters more than how much you work out. NPR's Maria Godoy looks at some apps that can help you keep track of what you eat.
MARIA GODOY, BYLINE: Like a lot of Americans, I've got some extra pounds to shed. So about two months ago, I started tracking everything I eat using an app called Lose It. It's one of several out there, like My Fitness Pal and My Plate. When I eat something, I can look up how many calories it contains. If it's not listed, I add it myself, like when I add creamer to my coffee.
All right. It says 35 calories per tablespoon. I use two tablespoons. So that is 70 calories.
Research shows that logging what you eat can be a powerful tool for weight loss. Basically, it's your food budget. And it's not that different from creating an actual budget.
YONI FREEDHOFF: You know, how many people out there have done this exercise from a money perspective realized, holy (expletive)? I'm spending that much at Starbucks. I think that similarly we might say that about the calories we're spending at Starbucks.
GODOY: That's Dr. Yoni Freedhoff, a weight loss expert in Ottawa. He has his patients keep food diaries. And he says patients that use apps are more likely to keep up with the logging. It makes sense. Most of us are glued to our smartphones all the time anyway. I use my app to track my exercise, too.
UNIDENTIFIED WOMAN: Three, two, one.
GODOY: I think you made this extra hard today.
Thirty minutes of cross training adds an extra 340 calories to my daily food allowance. It sounds good, but there's a limit to how much food we can actually burn off through exercise.
ABBY LANGER: Yeah. Your body does not work like that.
GODOY: That's Abby Langer, a registered dietitian.
LANGER: People who think that they can spend all day in the gym and just sort of negate all the food that they've eaten in terms of calories, that's just not how your body works.
GODOY: Because you can only burn off up to 30 percent of the calories we eat. And some people burn less. Another big concern - she says some people can become dangerously fixated on counting calories.
LANGER: There are some people who are predisposed to becoming obsessed with tracking the calories and just all the numbers and number crunching.
GODOY: She says anyone who's ever had an eating disorder should not use these apps. And they shouldn't be relied on alone. One study of young adults showed those who use weight loss apps lost the same amount of weight as those who didn't. Still, as long as you take it with a grain of salt, tracking your meals can be really helpful for some people. It has been for me. While the average American puts on about a pound during the winter holidays, I actually lost six. Maria Godoy, NPR News.
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