I'd guesstimate one third to half the cyclists I know from local group rides are overweight. And they're doing just fine. But I'm not seeing much evidence that cycling alone helps with weight loss. It's still mostly diet.
And unless your commute is long and/or challenging enough to be a high intensity interval workout, it probably won't burn enough calories to matter unless we're also cutting way back on unnecessary sugar, etc.
Over the years since a 2001 car wreck injury limited my mobility, I've dropped from a lifetime high of 205 lbs (about 50 lbs overweight for me) to 160 lbs. As I get closer to my optimal weight, it gets more demanding of sacrificing goodies in my diet. It's hard to get motivated to give up a little sugar and cream in coffee, a beer every couple of days, etc., when we've already given up 90% of our dietary vices.
My typical errands, commutes and one hour workout rides burn about 600 calories. That's just maintenance level exercise. It only keeps me wherever my weight happens to be.
It takes a hard 30 mile ride or longer causal ride to burn 1500-2000 calories and make up for those extra beers and muffins. Sometimes I'll take the heavier, less efficient hybrid rather than the road bike for casual group rides to compensate for the more relaxed effort over 40-50 miles.
But a typical commute alone won't have much effect on weight without some dietary sacrifices.
We just need to decide how much sacrifice is enough before it sucks all the joy out of living.
Personally, I wouldn't worry much about weight. Enjoy riding your bike. You're probably still faster than I am on climbs.