You've come to the right place! Everyone here has different ideas and strategies about what works hopefully we can help you find one that suits his needs!
What works best for me personally is calorie counting. Depending on your hubby's job, you COULD (no judgment- just an idea!) consider finding a calorie range for him and pack his food for the day. If he has 12 hour days, having his lunch and dinner mostly planned for might help.
Other things could be trying to eat breakfast, increasing water intake or increasing physical activity.
Lots of choices!