I completely understand your worries, especially where his health is concerned
Making anyone ‘change’ as you put it is an impossible task. Change has to come from within. It has to be something you commit to for yourself, and there is evidence to suggest that the more pressure people come under to change, the more resistant and rebellious they become. Let’s face it, unless you’re a doctor, telling anyone, especially someone you love, that they’re fat is going to hurt. In my experience, most people who are overweight are not blind to it, they usually just don’t know where to start to make those changes that can help them regain a healthy weight.
I completely understand your worries though, especially where his health is concerned, and this offers you a more tactful route to go down. A good place to start is at home. Yes, your husband might frequent restaurants, but you can both make sure the food you eat as a family at home is healthy and nutritious. Making food from scratch, from single ingredients, is always the best way to really know what you’re eating, so whoever does the cooking should bear this in mind.
I also think it’s a good idea to suggest he get a routine health check with your doctor if he hasn’t had one recently. Not only will this show you care about his health, it will also set up the conditions for your doctor to bring up the weight gain and check for obesity-related health issues such as high blood pressure and diabetes.
You mention your husband finds it ‘hard to keep up’ with your children. Maybe you can encourage greater fitness levels if you work in as much daily exercise as a family as possible. Start small and think varied to keep the interest levels up. Doing this together is far more motivating and it’s a great way to role-model health for the kids too.
So think encouragement rather than criticism and focus on gaining health, because losing weight will be a natural by-product of this.