One of my favorite tools is MyFitnessPal.com. It makes it easy for me to keep track of my protein intake as well as my exercise habits.
However, I also think that some features on MyFitnessPal are on crack. Specifically, the feature that tells me that “if every day were like today….you’d weigh X in 5 weeks.”
Weight loss doesn’t work like this.
Intellectually, a pound of weight equals 3,500 calories. If you burn more than 3,500 calories than you take in, you will lose a pound of weight.
At my height and weight, I burn about 1900 calories a day without doing anything extra. To lose weight, I would need to consume less than that.
I do DO extra. I exercise regularly. I also consume between 500 to 800 calories a day. It is normally around 600 or so.
This means, even at my sedentary calorie burn of 1900, I should have a deficit of (1900-600) 1300 calories. If 3,500 calories equals a pound, I should be losing at least 1 pound every three days (1300 x 3 = 3900).
But weight loss doesn’t really work that way.
At a light activity level, my calorie burn is actually 2210. At moderate level, it is 2500. This means my activity level minus my intake should mean I have a burn of about 1500 to 1900 calories a day, which should translate to about a pound lost every two days.
I lose weight slower than this. It can take me a week to lose a single pound despite what the math says.
This all brings me to MyFitnessPal, which I suspect uses the above math to calculate how much I SHOULD weigh in 5 weeks time.
I used to believe its predictions. I now believe it is about 10 pounds off.
Five weeks ago, in October, it was telling me I’d weigh 192-196 range. Occasionally, it would suggest I would weigh 189 or so. I weigh 200.
It is now telling me that in 5 weeks, I will weigh 178 pounds. For most of the past few weeks, it has been predicting low 180s. This means, it believes I will weigh in at 178 on January 4.
It’s not happening.
I do hope to be under 200 by Christmas. That’s right. I am giving myself 25 days to lose a pound. I better be successful.
Another reason MFP might be a bit inaccurate with this prediction is the exercise factor. Yesterday, which is the day the prediction is from, was a Zumba day. I Zumba’d my butt off for 65 minutes. This burns LOTS of calories. I, however, do not Zumba every day. I am hoping to make Zumba a habit twice a week.
I also want to point out how PITIFUL the difference in calories are when you go from sedentary (1900) to moderately active (2500).
Sedentary is described as:
- At work – you work in an office
- At home – you’re usually sitting, reading, typing or working at a computer
- Exercise – you don’t exercise regularly
Moderate is described as:
- At work – you are very active much of the day
- At home – you rarely sit and do heavy housework or gardening
- Exercise – you exercise several times a week and push yourself pretty hard
From not exercising regularly and sitting around to exercising several times a week and pushing yourself, you only earn 600 calories of burn? Ugh! No wonder losing weight is so hard.
