## What size will you be after you lose weight?

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REDDITORS’ BEFORE AND AFTER MEASUREMENTS ANALYZED

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 if you are losing under 55 pounds (25kg): You only have 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:

Want to make this graph yourself? OK.

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

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

November 15, 2014 @ 10:41 am

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

November 2, 2016 @ 10:49 am

HopeNaumansays:One inch for me also

June 17, 2018 @ 6:19 pm

HoracioOsays: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

Ray Van Raamsdonksays:But if your waist went from 32 inches to 38 inches then you may not have gained 60 extra pounds. Could be 150 pounds to 180 pounds so 30 pounds divided by 6 inches in this case = 5 pounds per inch.

September 18, 2018 @ 9:40 pm

dansays:Note that the end of the post says it’s about 6.1 pounds per inch for losses under 55 pounds. If you gain 30 pounds from a 32 inch waist, you’d end at about 37 inches

That is 37 = 32 + 30/6.1

November 11, 2018 @ 4:42 pm

Bill Greshsays:This seems way off to me. I’m 5’7″ 175lbs with about 24% body fat and a 38.5 inch waist. I’m currently training to drop my body fat down to about 12%, target weight about 158lbs (this doesn’t include inevitable muscle gains), and a 32-33 inch waist. This translates out to 2.6-3.0lbs of fat loss per inch of waist line. I’ve already dropped about 1.25 inches in 1.5 weeks while dropping less than 2lbs. I’ve obviously picked up some muscle from my HIIT cardio activities. Anyway, maybe it’s because I’m shorter at 5’7″, but 8-5-10lbs per inch isn’t even close by my approximation.

November 11, 2018 @ 10:20 am

dansays:I’m not sure where you are getting 10 lbs / inch from but the end of the post says that people like you who are losing under 55 pounds need to lose 6.1 pounds for a one inch reduction in waist.

There are other ways to arrive at this number. For instance the formula in this paper

https://bmcmedresmethodol.biomedcentral.com/articles/10.1186/1471-2288-12-115

Using your present height and weight, your waist is predicted to be

98 cm or 38.6 inches

(22.61306+2.520738*(27.4)+0.1583812*(40)−3.703501*(0)−1.736731*(0))

At 158 pounds, your waist is predicted to be

(22.61306+2.520738*(24.7)+0.1583812*(40)−3.703501*(0)−1.736731*(0))

91.2 cm or 35.9 inches

All I did was plugged in your current BMI of 27.4 and your target BMI of 24.7.

It predicted that if you lose 17 pounds, your waist will drop 2.7 inches.

This is 6.2 pounds per inch.

My estimate was 6.1 pounds per inch.

I looked at a handful of papers in the academic literature, and they found that a 1 KG loss is associated with about .9cm waist circumference.

This is also about 6.2 pounds per inch.

November 11, 2018 @ 4:38 pm

MartinHsays:I am severely obese, height 69 inches, waist 58 inches, weight 298 pounds.

I have lost 22 pounds and had no reduction in my waist size.

From a similar weight I lost approx. 40 pounds and my waist only dropped by 2 inches.

I would have thought that weight would be proportional to the square of waist size (like a cylinder) hence more weight loss needed at very heavy weights to lose an inch off the waist.

August 5, 2019 @ 7:06 am

Bethsays:It makes sense that the higher your initial weight, the more pounds you have to lose to lose an inch.

Imagine two people of equal height, one larger than the other, and say they lose an equal volume of belly fat. Let’s consider a circle around each of their waists- since they are the same height, they lose the same area of fat from the inside the two-dimensional circle we are considering.

If you take a given area away from a small circle, its circumference will decrease by more than when you take that same area away from a large circle, so the geometry of it means that the smaller person will have lost more circumference than the large one.

February 29, 2020 @ 7:57 pm

Janine K Johnsonsays:I think this must vary with a number of factors. In my 40’s I had a 24 inch waist. Calculating the number of pounds I’d have to lose to get back to that, I’d have to lose 131 pounds, in which case I’d weigh 69 pounds. I’ve lost 7.5 inches from my waist after losing 40 pounds, which means I lost an inch for every 5.33 pounds. If I get back to the weight I was then, at the same rate of inches to pounds lost, I’d have a 26 inch waist. Seems a more reasonable calculation for my body.

February 29, 2020 @ 8:08 pm