Fast days and Fitbits

This topic contains 5 replies, has 5 voices, and was last updated by dykask 7 years, 2 months ago.

Viewing 6 posts - 1 through 6 (of 6 total)

Twinmam

5:48 pm
4 Jul 17
Permalink

I’m sure a few of us have Fitbits and know our TDEE from using them. I’m also sure that those figures are higher than the online calculators usually work out your Tdee as they’re more accurate if using heart rate to calculate.

My question is: if I know from my Fitbit that my average tdee is say, 2400, does that mean I should use this to work out my fast day calories, which are technically supposed to be a quarter of normal calorie expenditure/ingestion. Therefore i would have 600 on a fast day, rather than the 500.

Anyone do this, and if so, how have you got on?

CalifDreamer

8:56 pm
4 Jul 17
Permalink

Twinmam, I had a Fitbit for 2 or 3 years and now have a Garmin Vivofit. I’ve never trusted the TDEE numbers on either and when I did look it was just for a rough idea. I think there are so many variables that even the estimates here are just guesses. It gives me a good guess as to where I should be. If you can easily do the 500 calorie FD, I would stick with that for quicker weight loss.

According to my TDEE numbers, a quarter would be 360 calories on a FD. At my target weight a quarter would be 339. I use the 500 number and still lose about 1.5 pounds per week. I’m wouldn’t want to go below 500. That wouldn’t be sustainable for me.

bigbooty

10:56 pm
4 Jul 17
Permalink

There is nothing magical about the number 600 or 500 or now 800. A quarter TDEE was just a number that Michael Mosley thought most people could cope with. It is not based on science. He took the idea on from Valter Luongo a researcher in longevity at UC Davis. Valter actually advocates zero calorie for four days per month. A true fast. Not sure how many would be able to do that. Hence 5:2 was born.

There was a recent study that looked at people who used weight loss tools like fitbit etc and those that didn’t. The people that didn’t use any tools lost more weight than those that use tools. What tended to happen was that those using fitbit etc tended to reward themselves with food more often because fitbit told them that they had achieved a goal, like 10000 steps or burned X amount of calories. Choose something that is sustainable and that you can do for the rest of your life. Im in maintenance now. I water fast every Monday. For me I find this easy, its sustainable, but that’s me. Find what works for you.

CalifDreamer

6:26 am
5 Jul 17
Permalink

It’s not just Fitbits and similar trackers that show calories burned and add extra calories as a reward or whatever to your calorie allotment for the day. Myfitnesspal does that as well. I totally ignore that and pay attention only to the actual calories or estimate of calories I actually put in my mouth. And the only days I keep track of calories are FD. I actually eat just a few things on FD that I know the calorie content of, so it’s a combination of 2 or 3 of those items. I go for large servings of low calorie, high fiber or bulk foods that I really like. Makes FD easy.

TrajanGregory

8:30 pm
28 Aug 17
Permalink

I also use a fitbit, but I don’t use the total expenditure as shown on the display … I instead use the pedometer caloric value, and add that value to my BMR … I walk a lot, and usually top 12000 steps per day, so, I wind up at around 300-500 LESS than the indicated total.

But, honestly, I don’t use those numbers to alter my food content – I eat the 600 calories, irregardless of what those numbers say …

If you stick to the program, and just keep doing it, you are going to have success …

dykask

2:06 am
29 Aug 17
Permalink

Trackers are great for showing relative differences between days, they aren’t so great for absolute accuracy.

When you go through the day and you see a number like 2400 calories, you don’t know how that number relates back to actual calories consumed. There are just too many variables:

* The accuracy of the heart rate monitor, optical ones tend to lag
* The accuracy of the calculations
* The power in the battery (hey I am an electrical engineer)
* The algorithm used, for example fitbits tend to be a lot more liberal on counting steps than garmins …
* The type of activity
* The temperature and humidity
* The health of the tracker wearer
* The amount of sleep
* The range of bacteria in the gut
* The type of foods eaten
* The amount of liquids consumed
* The timing of when foods are comsumed
* on and on …