What are you eating for your "normal" meals? DH gets hungry on plan too unless we kind of bulk things up. I found what has helped with us is having two different veggies at each meal, especially dinner. We'll usually do one that's kind of a faux starch (like cauliflower) or a little fancier (like green beans with a little bit of bacon and onions) and one that's more simple (steamed broccoli or roasted brussel sprouts). That way he gets variety instead of feeling like he's chugging broccoli. Plus, it makes the meals feel more substantial to him. He is generally not a salad for a meal kind of guy- unless it is very hot, and then, sometimes, he's okay with a salad for lunch.
For snacks, we make sure he has nuts, some string cheese, some veggies, some meat roll ups, a hard boiled egg, etc. I give him lots of options so that if he feels that he is really hungry and needs them, he has them. Most of the time, he only eats one or two, but he likes the feeling of knowing that he is choosing not to eat them, not that he can't. Also, while I keep my meat portions to roughly 4 oz, he has 6, sometimes more. We also do beans a fair amount- especially with like fajitas, or homemade burrito bowls.
Water also helps- instead of counting glasses- we got him a 1 liter Nalgene bottle and he aims for two a day. He prefers that over 8 individual glasses, and he drinks more if he keeps his water bottle with him.
Fighting back from the regain
Strong is the new skinny.