HOW Can I motivate my husband to lose weight?

I love my husband and looking out for his best interest. we've been married 4 years now, and have 1 toddler and another on the way. I know, some of us are fortunate to be petite and slim and others of us lack. Anyway, my husband's not even 30yrs and has gained nearly 30-40lbs!! I still am attracted to him, but would love to see a little less gut! He works hard and provides. He has allergies to raw fruit and veggies, which sucks, regardless I'm a big eater of those and I cook veggies for him. Anyways, what advice can I give to get him losing this before August, when his Dr appt is?