I know about the urge leaving after kids. Especially when said kid shave worn you completely down throughout the day and you have just got done putting the last screamer to bed.

One thing that helps to remember though, sex is a form of exercise, so you can count it to your daily total

It's good that your partner is wanting to change. Laying pressure on him though may just make him resentful. Just start slowly turning the wholehouse LC, letting him have his treats under the condition he gets them himself. With most of his meals being LC, you doing the shopping to where there is mainly LC snacks around, and most peoples laziness in grabing what's there instead of preparing, He'll be eating healthier by proxy. He may not be doign full Atkins, but even cutting down on carbs can be good for the health.

Be careful using sex as barganing chips though. Once you start doing that, it is really hard to get intamacy back in the relationship, and it does become just sex. I never had the labido surge that many report on LC, but you may be lucky in that area. I think losing weight and feeling sexier also helps.