It's hunger. Plain and simple. And it's BECAUSE he's still eating hi-carb foods.
The 2 biggest culprits for me (where I felt I HAD to eat something sweet after eating), were:
1) Fried Breakfasts (incl. fried bread, beans, fried potatoes)
2) sundat Roasts (incl. Roast Potatoes, yourkshire puddings, stuffig, etc..)
Sounds like your husband is in the same boat (at least on the Snday Roast side!).
I know the feeling well. It's a ravenous hunger, that you feel in your mouth more than anywhere, and no matter how mch you eat, you cannot get the hunger to stop.
Cut out the carbs at meal times, tell him to snack on meat, cheese and nuts, and I promise, you and he will be absolutely amazed at how the hunger disappears.
If you want to do a bit of reading, try reading up on Atkins Induction Phase. I had been ravenously hungry all my life until I started in induction all those years ago. Food was no longer such an issue in my life, and for the first time EVER, I was actually FORGETTING to eat meals, becasue I wasn't hungry! (I also got a new lease of life/energy, and found that sometimes, I was too busy to eat!)
Get your husband on this site, and get him to ask LOTS of questions. I'm always happy to answer PM's (so is almost everybody else!) I know exactly how he feels - it is not impossible to re-gain control.
Give him my best.