For decades, I’ve heard that people start putting on weight shortly after the start of a new relationship. It’s mostly said of men but I’ve recently come across an article that described the same phenomenon for women.
I see correlation but not necessarily causality. More like people tend to enter stable relationships when their brains are fully grown and their hormonal system turns towards weight gain.
There is research around this derived from side effect of studies about whether taking the contraceptive pill made women gain weight. What was found was that women often did gain weight co-incident with going on the pill. However:
However my source gives no cite for this proposition.
I haven’t seen (or looked for) scientific studies on this, but it has been regarded as an extremely common phenomena for at least as long as I’ve been in the dating game. “Been there”, echoes all around.
The reasoning is simple, and rings true to countless millions: when you’re single, you need to make an effort on your all-round fitness to attract potential mates. It’s hard work, for many.
Once you have secured a partner, the immediate & pervasive need to present fitness is removed, and easier, more satisfying ways of life tend to return, leading to weight gain.
Corollary reasons include many people don’t care to cook (well) for only themselves, but are keen to practice culinary skills in a relationship. Tasty food is often fattening food.
My completely unscientific-- which is to say, I took no notes, and there is probably lots of observer bias, albeit, I have no investment in any outcome-- is that people in relationship seem to gravitate toward a mean.
In an extreme, take a really skinny person entering a LTR with someone borderline obese; a year later, you’d find that the gap in their sizes and closed a bit.
The bigger the gap, the less it would close.
There’s a working mechanism for it, in that people in a relationship would tend to start sharing their food habits, and exercise habits-- the slender one might eat a bit more junk food, particularly when someone else is buying, and start riding in the partner’s car, justifying it because they’re going there anyway.
Meanwhile, the less in-shape partner might be happy to eat healthier, home-cooked meals as long as someone else is doing to cooking, and discover that “boring” exercise is fun when it isn’t done solo.
It’s not different from lots of the other changes we make to accommodate partners. If one tends to be a morning riser, and the other late, they each gravitate to getting up more toward the same time. He’ll giver her favorite TV show a chance, and she his. Unless one finds the other’s intolerable, they’ll usually watch each other’s, just to do it together.
If he’s not a dog person, but she has one, he’ll go on walks with her when she exercises the dog. If his car is a manual, she’ll learn to drive it, particularly if she doesn’t have her own car.
Here’s the tricky thing: everyone comments on the people who gain weight, looks for a reason, and a place to lay blame. When the other partner loses, if it’s enough for people to notice, they think it’s good, but don’t look for a reason-- they assume it must be deliberate.
Some might compliment the “loser,” or even ask about their program if they are the sort to want always to discuss diets, but most people say nothing other than “You look great,” unless the loss is very dramatic. And then, there might be some whispering to make sure the person is not ill, before mentioning it.
So, while there’s something akin to “regression to the mean” between couples, it’s the one who gains that attracts to most attention, to the point that in retrospect, people just remember that a lot of people gained weight when they met someone.
That’s close to what it was like at the start of my last relationship.
I was not obese, though but noticably overweight, while my ex was very underweight (I remember how a ribs were clearly visible under her skin). After about 6 months, I had lost 20-30 pounds while she had gained… 20-30 pounds.
Among the possible explanations you’ve given, the following ones apply in our case :
We did cook together, though. That was one of the fun aspects of our relationship. That, and long bicycle rides in the countrysides, which I rediscovered as an adult thanks to her.
Not related to weight, but still relevant in our case :
You also eat out more early in a relationship, i think.
Very true, but for most that’s not a sustained influence on weight, I think.
At my previous job the director of our department was an workout fanatic that did ironman competitions and would often gain a 15-20 pounds before an event. When he went through a divorce he became even more intense. I saw him about two years ago and it looked like he gained 30 lbs, so I asked him if he was getting ready for another ironman event. He said no, that he meet his new wife in one of the events and they both stopped working out and gained weight. Apparently they both worked out because they loved food and that they could eat what ever they wanted, once they found each other they stopped working out so much but kept eating.
Just one data point yes, but I’ve heard similar stories from many people including myself.
I’m average height but scrawny. My new wife is short & petite. IOW can pass for late 20s when you can’t see her face. We’re both 64.
What changed for us was that while we were each single but not actively chasing anyone, we each ate separately a lot at home. Which means we each controlled our portions and we each eat what fits our style. And we’re eating mostly home-cooked meals.
We decide to start dating each other. Now we’re going out for restaurant meals 5-8 times a week. Often leftovers come home because most restaurant meals are huge and we are rather small, but that also means that most of the at-home meals are restaurant-cooked too. Little home cooking going on. More fat, more salt, more butter. More carbs. More everything. More cocktails are consumed, fewer glasses of wine.
We co-habit a while then get married. No change in restaurant habits. Fast forward a bit over a year: Surprise: we’re both up 10-15 lbs. Ouch! Despite their intriguing name, love handles aren’t really a great addition to our bedroom routine. 
I do not know of any research that settles this issue. It does make sense that improved mood accompanying the start of a satisfying/exciting relationship might enhance one’s appetite - for food, that is. Another factor could be involved…
Relationship time, when a young person’s fancy turns to eating out. 
Do you have a cite for the article? Because what I’ve heard and noticed is just a little different - that the weight gain is not at the very beginning of the relationship but after they have “settled in” to the new relationship. Not five years in, but not five weeks or even months either.
I can only go by my parents, married in 1947. Dad claimed he weighed the same (130 lbs or so) all his life since he was a teenager. Mom was, judging from her wedding pictures, an attractive girl, not thin but not fat either. I never knew my mother as other than fat, maybe 180 to 200 pounds. Dad said she gained it in their first six months of marriage. I speculate her level of activity changed from an outgoing teenager to stay-at-home wife and later, mother. She also was a good cook and loved to do so. This all contributed in her case as far as I’m concerned. Dad, he more or less did what he always did before I suppose, relatively active unlike mom.
I don’t.
It wasn’t a scientific article (hence my OP), just something that appeared on my Google opening page about a week ago.
I guess it depends on how you define “the start of relationship” and “settle in”. I mentioned 6 months in my last post, which is probably the time when “the start” transitions into “settling in”.
In the case of a marriage, and speaking of ones that began decades ago, where pregnancies before the second anniversary (an even the first) were pretty common, I’m sure lots of women gained, and no, I don’t mean the pregnancy itself. It’s pretty common to retain anywhere from 10 - 30 pounds after the first baby, and never lose it, and another five pounds or so for every baby after that; it has a little to do with aging, and a lot to do with hormones.
Albeit, the more you gain, the more you are likely to lose at least some-- but as Mammy said to Scarlett “You ain’t never gonna be 18 inches again.”
In my own particular case, I gained a lot with my son, and never quite lost all of it, but did finally get back to about 10 pounds of what I weighed when I was married (by the time of his bar mitzvah, but hey). For the whole time I was nursing, which was over two years, I weighed almost as much as I did when I was pregnant. Honestly-- I gained about 35 pounds during pregnancy, and after delivery, lost about 9. He weighed 8 & 4 ounces.
If I’d been popping out a baby a year, and never had time to do things like ride a bike or join a yoga studio once the first-born was in school 6 hours a day, I’m sure I’d have an unflattering reality show by now.
My new wife gained about 10 lbs total with her first pregnancy, then punched out an 8lb kid. The baby doc was concerned she wasn’t gaining enough weight. But the kid emerged healthy & robust and has thrived ever since. The extra 2 lbs faded quickly thereafter
She did the same thing a couple year later w kid #2. Apparently it can be done although it’s not the way to bet.
Both kids are in their 30s now and she’s now about at her peak pregnancy weight from back then. Again not the way to bet, but it seems it can be done.
It’s uncommon enough that women who deliver healthy, term babies without ever appearing pregnant, make the news.
That’s not exactly what makes the news- I’ve never seen anything in the news about a woman who only gains ten pounds during a pregnancy or who never appears pregnant who delivers a healthy, term baby while receiving prenatal care. What makes the news are people who either don’t know they are pregnant or who were hiding the pregnancy.