Puzzled?

So today i am riding along the big river trail at a leisurely pace and come upon two women, down in the drops, looking like they had a mission. I politely but with intent say "On your left," assuming they would just continue their chatting and move over even slightly to let me go by.
I wasnt hammering ( ahem it is October and it is 40 degrees) but moving along a bit faster than they were. So one gal pulls over and the other one, lets call her yellow bike lady, gets OUT of her saddle and starts sprinting. OK.

I turn to blue bike lady and casually say "Oh sorry i wasnt sure if you guys were just chatting and i didnt want to be sitting on your wheels without you knowing i was there." Basically saying i didnt want them to suddenly slam on the brakes or decide to ride 12 mph when i was going 20 mph.

Blue bike lady "Oh dont worry, we are chatting. And she ( yellow bike lady) has her OLD HEAVY BIKE so we arent going fast." I am thinking that yellow bike lady was going fast, fast enough to NOT LET ME PASS!
So i say "ok, thats fine i am not in a hurry," meaning "Ok i am not going to race anyone ..today."

BBL: " NIIIICE OUTFIT! Do you race? Do you ride on a team.." the questions started flying.
Me: " Yea I do."
BBL: " And you are so slim. You must run. Alot. Do you run?..How far you riding today? We are on our long ride today. We live in...Apple Valley"
Me: "Yea alittle running... more biking."
At this point i am trying to figure out which route i will take so as we approach the port-a-potty I say "so you gals going up the hill or continuing on water street?"
BBL: ( As Yellow bike lady is about 10 feet ahead of us, winning this part of the circuit ride)
"We need to use the porta potty."
Me: "Ok great, enjoy the day and have a good ride!"

So for the next part of my ride home I was thinking...and I have thought of this many times...
Why do people, usually always women find that it is Ok to say to someone, a complete or total stranger:

" SO YOU ARE SLIM, YOU MUST RUN."

Think in another context...

" SO YOU ARE CARRYING SOME EXTRA WEIGHT IN YOUR LEGS ( MIDSECTION/name your anatomy)...YOU MUST NOT RUN?"

I am by no means saying it is a burden to be slim. Genes, good healthy lifestyle, good diet, blah blah blah...but over my years as an athlete and as a normal person doing normal daily things like shopping, working. eating out, etc..I continue to be amazed that people, especially women, find it acceptable to say to me "You are so skinny. You had better get something to eat." or "You are slim you must workout ALOT." And these are, like Blue bike lady, people I dont know. Or may have just met, say at a party.

Would you say to someone you dont know or dont know well:
"You look like you have gained some weight. You had better order the diet plate."
OR
"You are looking heavy. Legs a little thick. Have you thought about taking up running?"

This isnt a rant or a vent. I am lucky to have the genes i do and to really enjoy the lifestyle that allows me to have a healthy body. And yes, like alot of women, at one time I fought and conquered an eating disorder. But until i was mature enough to understand it, comments like the ones today would have made me feel insecure about my body. But today it doesnt. It just makes me feel grateful that i know my body...Even if Blue bike lady is comparing herself to me, and if Yellow bike lady "Won" the workout!