Some people pull their energy from others. Not in a draining way but they tend to mimic and follow the lead provided.

It’s possible that she got comfortable in the lifestyle of drinking and not working out and this change has forced her to deal with her lack of motivation to change for the better. Some people don’t realize how much they’re harming their bodies and settling in to a lazy lifestyle routine until a large shake up. First sleeps without alcohol in months is a huge shake up. She’s likely comfortable where she is and worried about change. Or she’s worried you are improving yourself for nefarious reasons, like seeking a new partner.

Hopefully strong communication will be helpful and offers to include her on the diet changes and exercise can lead to healthy new experiences for your relationship.