projectpolemics: Also, muscle is way denser than fat, so if she's chubby and active she'll bulk up quite a bit.
Hit the nail on the head right here, if she's doing more strength training then even if she does burn more calories than she takes in, she'll still bulk up. Cardio and Aerobic exercises are what really burn fat, so if that's what she's focusing on then it'd be tough for her to continue gaining without really increasing how much she eats.
Bruh. Lol, I've seen several SSBBWs in the 400Ibs & 500Ibs range that fake huffing, puffing, & struggling just to get up in their clips, but mess up at the end of recordings where their boyfriend/feeders ask "want to go (eat out/movies/etc..) & they'll hop right out of bed & fast walk off without a problem or huff lol. We're talking rolls of softness, not bulkheads either hence SSBBW. Active & gaining's not a bad thing at all! Enjoy life & all your favorite activities with her! Let her workout but SPOIL HER SILLY! & Contrary to the Calories-in-Out Idea, there are certain food items & herbs that make the calories "stick to you" more! Microbiomes! Look it up! Makes gaining with any metabolism that much easier.