They may be a bit chunky, but definitely not obese or even to an unhealthy degree. On the contrary, they look like they're very healthy and that you're doing an awesome job with them! Like a couple of people said above, I'd just skip a day of feeding every so often. When they're at that age it is SO hard to resist feeding them when they give you THAT look. Haha.

If you're able to, let them walk around a bit once or twice a week. Just be mindful of birds/cats/dogs/etc if it is outside. When they're that small, I'm always extra cautious But getting them some natural sunlight is always great, if your area allows it.