The interactions available to deal with weight gain/loss depend on which packs you have to a certain degree.
In base game, you have the exercise equipment. If you watch carefully, you'll see that the weight machines, punching bag and treadmills will affect a sim's physique differently too. You also have the reward potions you can use to send a sim to either extreme, fat or skinny. And if you don't mind cheating, you can use the CAS.fulleditmode cheat to get access to the sliders and adjust a sim's looks to your liking.
In the Cool Kitchen, there is an ice cream maker that you can use to make different ice creams that do different things. You can easily have a sim gain or lose weight by eating the right ice cream.
Then there's the yoga mats from Spa Day. Those are pretty good for slimming down a sim gradually more or less.
And Strangerville gave us the sparring bots that also affect a sims fitness.
The Fitness pack has the rock-climbing wall. And Snowy Escape has rock climbing built into the landscape and skiing and snowboarding. All affect a sim's fitness levels.
City Living has the basketball goals and courts.
Seasons has the ice- and roller-skating rinks.
And there are other things that will affect a sim's fitness like football and cheerleading in High School Years although it's pretty limited what they can gain/lose in any given session.
So, there are lots of things you can do other than jogging that will affect a sim's fitness. You just have to have the packs that gave us those things.
Hope this helps.
Yes, swimming will definitely affect fitness. I forgot that one, but it certainly does.
Bike riding probably will but idk for sure. I don't use the bikes except for the kids for the two child aspirations. Once they age up, they don't ride them again.
Horse riding I'm not sure about either. I haven't seen where sims lost or gained weight in my game, but I really haven't played horses very much.
Hope this helps.
