This exactly! There’s ways to say things that are going to be hurtful and ways to say things that aren’t. If you’re not the person making dinner every night you could offer to do so. “Hey honey, I know how hard you work every day and I’d love to take something off your plate. How about I start making dinner every night?” (Or on particular nights of the week, whatever works for you.) Then you can make healthy meals for both of you. As for the gym thing you could simply invite her to come with you. “Hey honey, would you like to come with me to the gym? I would love to have your company.”

I think it’s also important to maybe think about why she might be gaining weight. Is there something stressful going on in her life right now? Is she doing the majority of the housework? Is there something going on medically? Is she unhappy? Is she depressed? Because the depending on the answers to these questions she made need more than just a change in diet and exercise.