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What size will you be after you lose weight?

Filed in Ideas ,R ,Research News
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How many pounds do you need to lose in order to reduce your waistline by one inch? How many kilos do you need to lose to reduce your waistline by one centimeter?

We wanted to find out. We were having trouble finding published data (though we are expecting some soon), so we turned to Reddit, where the progresspics subreddit contains people’s before-and-after weight change stories. Most posts contain only pictures, but if you do some web scraping, you can find cases in which people post their before-and-after waist measurements.

We found 46 such cases, typed them up, ran them through R, tidyr, dplyr, and ggplot and made the picture above.

Multiple regression tells us that on average, for every 8.5 pounds lost, people dropped an inch off their waist. (And for every 1.5 kilograms lost, people dropped a centimeter off their waist.)

Every 10 pounds lost was accompanied by 1.18 inches of waistline reduction. (Every 5 kg lost was accompanied by 3.33 cm of waistline reduction.)

The picture is a bit rosier for those who were losing smaller amounts (under 55 pounds or 25 kg): They only had to lose 6.1 pounds to lose an inch (or 1.1 kg to lose a centimeter).

Want to see the data split out by gender? Voila:


Click to enlarge

Want to make this graph yourself? OK.

Why am I doing this? Hal are following up our face morphing stuff with body morphing stuff.


  1. RichardH says:

    Perhaps inches x inches x height would give a better fit vs lbs

    November 15, 2014 @ 10:41 am

  2. Scott says:

    Eight pounds = one inch is exactly the case with me.

    November 2, 2016 @ 10:49 am

  3. HopeNauman says:

    One inch for me also

    June 17, 2018 @ 6:19 pm

  4. HoracioO says:

    Hi, nice regression study! Thanks for sharing.

    Been trying to figure out this myself, but there will be a few of different factors that will change the number (mainly height and current weight).
    I used the numbers of my own weight gain through the years and figured out that the relationship is not linear/constant, and the higher is your current weight, higher is the number of pounds to reduce your waist size.

    August 27, 2018 @ 5:48 pm

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