Also not taken into consideration is the reliability of BMI. When I watch an older program (like Columbo or Matlock) with Jane Fonda type aerobics featured, I'm always taken aback at how flabby the ladies look. But that was the ideal back then. The ideal look today is a lot more muscular. And resistance training is part of most exerciser's regimens. Even my 82 year old mother does strength training. And who hasn't seen the video of Ruth Bader Ginsburg planking?

Back in the '80s I smoked 3 packs a day & had ulcers. So I didn't eat much & threw up a lot. And I was very skinny - you should see my wedding pictures!

Around 1990 I quit smoking & ate everything in sight. I went from being addicted to nicotine to being addicted to food - especially popcorn, potato chips & anything bread-like.

The main difference I see between then & now is that smoking is not as accepted, nor is it as cheap - there's no way I could afford to smoke now.

I wasn't able to eat low carb until I started OA & actually worked the steps. On my way to my first meeting I ate my last bag of potato chips. Within a few months I was able to ditch the popcorn & anything made of wheat flour and/or sugar. Tho it took me a LONG time to figure out the rest of low carb for a food addicted t2 diabetic. I still eat too much, but I'm getting there.

Possibilities:

Antibiotics or other medications (they give antibiotics to animals to fatten them, probably works the same on us)
Estrogenic properties of plastics. (Male sperm count keeps decreasing)
Pollution?

Just a few off the top of my head.

It isn't genes. You don't have huge sudden swings with genetics. Epigenetics caused by something environmental is much more likely.

I think an argument can be made that we are in fact eating more. That doesn't mean that I think that the eating more causes the weight gain, it might be as much a symptom as the overweight itself, rather than root cause. Food availability and dietary recall are astonishingly crappy ways of knowing what and how much the population is eating.

One thing that might need to be looked at here is the contribution of lean mass to bmi. I've seen pictures of some of my male ancestors, they didn't just look lean, they also looked like they carried less muscle than more recent family members. The bmi calculator tells me the lower end of a normal body weight for me is 125 pounds, I'm not getting there without losing a lot of muscle. And hopefully some sort of intervention.

When I was a kid, the cottage cheese and a burger patty diet plate was still a thing in cafeterias. Maybe dieting actually worked back then. My favourite meal was when my Mom made cottage cheese, kolbassa and fruit salad plates at home. A little sugary, but a relatively low carb meal compared to what counts as diet food later.

I think I found the reason:

https://www.buzzfeed.com/sophiegadd...s-from-the-past

One more possibility to throw into the mix: Not just how much we're eating or what we're eating, but how often.

Jason Fung has a theory that much of the obesity epidemic can be attributed to eating more often (snacks, "six small meals"), which keeps insulin perpetually raised: Critical Importance of Meal Timing

Personally, I think it's probably a combination. Sure, lots of kids ate PB&J on Wunderbread for lunch every day. But there was recess twice a day and kids ran around. In high school, kids walked half a mile to catch the city bus instead of getting car-pooled and had PE every day or played sports. After school, their moms told them to eat an apple (not a quart of orange juice and a granola bar) and then yelled at them to go outside. Then they ate a dinner that was cooked from whole foods, even if it did include potatoes or rice every night. Dessert was an occasional treat and, even then, sometimes it was fruit. After dinner, you didn't eat again until breakfast 12 or 13 hours later.

Now, everyone eats for 16 hours a day, PE or recess is a couple of times a week, getting to a bus stop more than a 1/4 mile away is a flipping tragic inconvenience, and most people I know always have ice cream in the freezer. My guess is that if you've got constant eating and/or lots of sugar and carbs going on for a long period of time, you're going to get fat. Mild levels of steady eating and carbs can probably be offset to some degree by exercise in otherwise healthy (young) people.

LOL! That will take care of your appetite.

I grew up in the 50s and 60s and my family was clearly an outlier. We always had soda in the house. There was a local bottling plant called Brookdale Beverage and you could get a case (12 bottles) of soda in glass bottles there. They must have had two dozen flavors at least. It was a treat for my sisters and I to go with my dad on a Saturday morning to bring back our case of empties to be reused, and to get new bottles. My sisters and I were each allowed to pick a couple flavors and then my dad picked the rest. We always had snacks in the house from door-to-door vendors: potato chips and chocolate chip cookies from the Charlie’s Chips man and donuts from the Dugan Donuts man. After church on Sunday my folks always stopped at the bakery for coffee cake and pastries. Ice cream was a constant as my mom was an ice creamoholic. In addition to ice cream in the freezer we often went to Holsten’s (later famous as the location for the very last scene of The Sopranos) for their wonderful homemade ice cream.

Yet my sisters and I were all skinny kids. Of course I did walk to school every day starting at age 6. It was 3/4 of a mile to school and we came home for lunch every day too, so that was 3 miles of walking daily. Not many 6-year-olds walk three miles daily these days, but my mom had two toddlers at home and was not about to drive me!

Then I hit puberty and moved to a school less than a 1/2 mile from home, and no coming home for lunch so much less walking, plus the hormone storm. And weight began slowly to creep up.

Age 11, just before the hormone storm:

3 meals a day plus snacks is coming from the American government and the doctors. When I was pregnant and had gestational diabetes, I was told to eat 3 meals a day and 2-3 snacks between. I kid you NOT. The suggested snack was Ritz and peanut butter. I kid you NOT. When I got home from the meeting with the nutritionist I tossed everything in the trash. And continued reading DANDR for support.

Merpig-- I too walked to school in the 60's and when we got home played outside until dinner or dark. We were all skinny in the neighborhood. Funny how I had forgotten how many miles a day we traveled each day as kids!!

Omg, that reminds me of James Lileks' Gallery of Regrettable Foods. I'd forgotten all about it. Thanks for the laugh.

I had to look it up to see what Eggs Meurette - those are supposed to be eggs poached in red wine sauce. I love eggs, but I don't know if I could bring myself to eat those. They look like small skinned heads. Rat maybe?

A modern picture of Eggs Meurette looks much more appetizing.
https://www.seriouseats.com/recipes...nch-recipe.html

Haha, you can certainly fall down the rabbit hole at the Gallery of Regrettable Foods. No wonder people were thinner then! Who would actually EAT those things?

I recently watched the documentary Apollo 11 (2019) at the theater. I was amazed at at all of the think people. They showed the crowd (hundreds, thousands) who drove and camped / parked to watch the 1969 lift off. They were all thin. I had to look hard, and saw one guy with a beer belly (with a can of beer in hand). That was it. Kids were not over weight either. Amazing.