Thread: FitBit Inaccuracy? Calorie deficit seems really high in order to lose weight

Hello,

I've been seriously tracking my weight for 3+ years now with a Fitbit, MyFitnessPal and a food scale. I feel that I'm counting my calorie intake pretty well. I try to log everything as accurately as possible but I found that I need pretty high calorie deficits to lose weight.

Background: I'm a 6-foot, 46-year-old Male. I was 225lbs back in 2017 and now I'm at 175lbs. I exercise 3 days a week and bike often as a hobby. I've tracked my numbers via Excel, weigh in daily and average weekly. I've also tracked calories in, calories out, deficits, and macros.

Whenever I've been sick and laying around all day, my Fitbit registers around 2400 calories so I figure that should be my basal metabolic rate. When I'm exercising, my FitBit can register upwards of 3000-4000 calories burned in a day

Here's the deal though, I've run weekly averages of different daily calorie deficits and came up with the following numbers:

• 800-1200 daily deficit: I'll gain .5 to 1lb a week
• 1200-1500 daily deficit: Seems to be maintenance, not much gained or lost on average
• 1500-1700 daily deficit: I average about .5lb - 1lb weight loss per week
• 1700-2000 daily deficit: I average about 1lb or more weight loss per week (this is a higher range that doesn't happen often)

Shouldn't a daily deficit of 500-1000 lead to around 1lb weight loss per week instead of weight gain? Is my basal metabolic rate off or something?

I've tested this out and have gone on bulking and cutting phases multiple times and the above numbers are just about spot on. For instance, I gained about 15lbs over the winter with a 800 daily calorie deficit and lately, I've been keeping a deficit of 1700 and lost 10lbs since March, about a 1lb a week.

Has anyone experienced similar issues with a Fitbit or have any advice on this?

Thanks

you shouldn't trust those numbers. if your fitbit says you burned 4000 calories and you eat 3200 ("800 deficit"), you could easily be really burning only 2600 calories and being in a 600 calorie surplus

Originally Posted by misterblick

• 800-1200 daily deficit: I'll gain .5 to 1lb a week - no, that's a surplus of 250-500 a day
• 1200-1500 daily deficit: Seems to be maintenance, not much gained or lost on average
• 1500-1700 daily deficit: I average about .5lb - 1lb weight loss per week that's a deficit of 250 to 500
• 1700-2000 daily deficit: I average about 1lb or more weight loss per week (this is a higher range that doesn't happen often)

So it looks like your actual maintenance is where the fitbit is telling you that you are in a 1300 calorie deficit....

My advice is don't bother using it. Just stick to the same calorie level every day and make small adjustments once every 2 weeks.

Thanks for the info. Much appreciated.