Science

Quarantine Weight Gain? What Two Recent Studies Get Wrong

This post contains a video, which you can also view here. To support more videos like this, head to patreon.com/rebecca!

Content warning! I’m going to be talking about weight loss, weight gain, health, calories, food, and exercise. If you have a problematic relationship with any of those things you may want to give this one a pass!

A few months ago I made a video about why it’s actually okay and healthy for some people (mostly shorter, sedentary women and those who are actively losing weight) to eat 1,200 calories per day. Not everyone liked that! Which I knew would happen, because I know that a lot of my audience is concerned with social justice, and one important aspect of social justice is stopping discrimination against fat people, calling out unhealthy beauty standards that particularly damage women, and criticizing unscientific trendy diets like juice cleanses and teas that make you poop yourself. I absolutely agree that all of those efforts are necessary — I mean, that is just one of many reasons why I will never be an influencer. I will never try to sell you a tea that makes you lose weight by pooping yourself. 

But at the same time I also acknowledge that too much weight is unhealthy for many people (including myself — I have severe back issues that leave me literally crippled when I carry too much weight), just like being underweight is unhealthy for many people (possibly myself, I don’t know as I have never come even close to finding out). While I don’t think it’s okay for anyone other than a person’s doctor to tell them anything about their body or their health, I also think it needs to be okay to admit the preponderance of evidence that shows how weight negatively affects health outcomes.

So! While I don’t often talk about these topics because I do not enjoy being yelled at people on “both sides” of the obesity debate, I am very interested in it. And so my interest was piqued when I saw this post flying around Twitter:

“Holy cow: 42% of Americans report undesired weight gain during Covid 19. The average weight gain is 29 lbs. And 41 lbs for Millennials! This will ramify for years to come.”

Okay, no matter how you feel about weight, 41 pounds is a large amount of weight. Like, a suspiciously large amount of weight. And even the “average” of 29 pounds is pretty impressive when you’re talking about almost half of all Americans. Like, I’m not one to lose much sleep over the “obesity epidemic” but I’ll admit I was worried about us for a minute. According to this study from 2017, the average American was previously gaining 1 to 2 pounds per year. This is two pounds per month.

But then I looked at the actual data and let’s get this out of the way early: that summary of this poll is wrong, and the poll itself isn’t great.

Okay, so this data comes from a self-reported survey published by the American Psychological Association. In February of 2021 they surveyed about 3,000 American adults and asked them if their weight had fluctuated during quarantine. So already this isn’t clinical data, this is just asking people a question and hoping that they will respond accurately. Maybe they’re lying, maybe they’re underestimating, maybe they’re overestimating, who knows? That doesn’t mean we throw the data out, it just means we take it with a grain of salt.

Of those surveyed, yes, 42% said they gained more weight than they liked. OF THAT 42%, the MEAN number of pounds gained was 29. The MEDIAN was 15. In case you, like me, have completely buried the memory of sixth grade, here’s a refresher: “mean” is what you usually think of as “average.” If these ten people reported the following weight gain, the average would be 26 pounds gained:

10 lbs

10 lbs

10 lbs

10 lbs

10 lbs

20 lbs

20 lbs

30 lbs

70 lbs

70 lbs

Does describing these ten people’s weight gain as “an average of 26 pounds” really explain the situation? Or would it provide a clearer image of what happened if we summarize it as “half the subjects gained 10 lbs?” That’s why we have the concept of “mode,” the number that occurs most often. The “mode” here is 10. The “median” is the number literally in the middle when you stack everything up in numerical order: in this case it would be “10” and “20” (as 5 and 6 out of 10), so you’d average those for “15.” The median is 15, the mode is 10, and the mean, or average, is the scariest number at 26. 

That’s helpful to know because when the mean is significantly larger than the median, we know that the data is positively skewed — in my sample case, two outlier subjects gained a LOT of weight but everyone else gained less than half of what they did. So the APA survey reporting a mean of 29 and a much smaller median of 15 tells us the same thing: most people who gained weight did not gain 29 pounds. A few people gained a whole lot of weight, while most people gained much less.

I can’t believe I’m using sixth grade math for something useful in real life. I’m so angry that my math teacher was right.

Also I just made up those example numbers to make them easy to add and divide in my head but they ended up being almost exactly the same mean and median as the survey. I’m like a genius. Should I say I meant to do that? No. Too late. Moving on.

Anyway even the median of “15 lbs gained” is way more than the previous average of 1-2 lbs for a year. But! Remember that 15-pound median isn’t among all the surveyed people, just the people who said they experienced unwanted weight gain, which was only 42% of respondents. 18% of respondents said they experienced unwanted weight loss (mean: 26 lbs, median: 12 lbs, again a big difference suggesting it’s positively skewed). 39% of people reported no change in weight.

I’m bad at math, so let’s try to simplify all this. Let’s take 10 people and see their weight change, using the mean reported pounds:

0

0

0

0

-26

-26

29

29

29

29

That adds up to 64. Divided by 10, that gives us a mean average of 6.4 pounds gained per person over the course of a year. Now that’s a number we can compare to the previously established average of 1-2 pounds per year.

The real headline here isn’t “42% of Americans gained an average of 29 pounds in quarantine.” If anything, it should be “Americans gained three to six times more weight than usual in quarantine.” Or, “The average American gained about half a pound per month of quarantine.”  And remember, that was self-reported data. We don’t know if these respondents even had a scale, or if they were just taking a good guess.

We actually do have another study that uses data from people’s scales. 269 participants had bluetooth-connected scales that reported data to researchers from February 1 to June 1, 2020, and those people did experience an average weight gain of about 1.5 lbs per month. Wow, that’s about what the previous survey would have us think people gained! 

The problem with this one is that it was only based on the first month or two of quarantine, collecting data from anyone in the preexisting Health eHeart Study who reported at least one weight in February of 2020 and one weight after quarantine began in their state (somewhere between March 19 to April 6) but before June 1, 2020. So let’s say I weighed in at 140 pounds on February 28 and 142 pounds on March 20. I would go down as “gained an average of two pounds per month”.

Look, I’m a weird obsessive nerd so I weigh myself pretty much every day.  I’ve gained three pounds by eating a ton of salty food. I’ve lost three pounds by having a really long pee. I just don’t think that checking on people’s wait for one or two months is quite enough data for us to say that Americans have gained 1.5 pounds per month in quarantine.

All that said, I would not be surprised to learn that people have, on average, gained wait in the past year. A hell of a lot of people, myself included, eat and drink to curb anxiety and depression. I see conservatives using these studies to say that lockdown was awful because closing gyms led to this weight gain but let’s be honest, the science tells us that weight loss happens in the kitchen, not the gym, and many of us have been dealing with our stress by ordering in, whether because we’re avoiding going out to grocery stores or because delicious pad kee mao is the only thing that makes life worth living some days. Yes, I’m eating four days of calories but I briefly remember what it is to be happy and also I’m supporting a small business, leave me alone.

So yeah, did Americans gain weight during this global pandemic? Probably. Was it an average of 29 or 41 pounds? Absolutely not. Was it caused by quarantining or the fact that we had to watch half a million people die while a corrupt government twiddled their thumbs and clueless conspiracy mongers screamed about their freedoms? No way to tell from these studies. If quarantine was the cause of an increase of half a pound per month, does that mean it would have been better to not quarantine? ABSO-FUCKING-LUTELY NOT. I gained about ten pounds in 2020. Three months into 2021 and I’m back to where I was at the start of quarantine (but I can do pushups now!). A little weight gain can be reversed if the person wants. I can’t say the same about a COVID-19 diagnosis.

Rebecca Watson

Rebecca is a writer, speaker, YouTube personality, and unrepentant science nerd. In addition to founding and continuing to run Skepchick, she hosts Quiz-o-Tron, a monthly science-themed quiz show and podcast that pits comedians against nerds. There is an asteroid named in her honor.

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One Comment

  1. So I’m also one of those people that also weighs herself everyday. I also have quite a long term relationship with a weight loss program. Before bariatric surgery, I weighed 440 pounds. Before the quarantine I was about 170. Over last summer I gained about 15 pounds from baking and eating too much and not moving my body since I wasn’t at work. I’ve lost about 10 of that.

    Here’s the thing. My dietician drilled into my head that the program didn’t consider any weight change under 2 pounds as real. Salt, a good poop, etc all can significantly change weight.

    I’m not stressing about my weight. Once I went back to work and stopped baking everyday, I lost it. I’ve started training for a 5K and lifting weights. My weight is what it is. As long as it isn’t 400+ pounds, I’m happy.

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