If your wife is hungry she isn't eating enough good fats. If she is eating low carb she needs to increase her fats. She can throw away any low fat products (most of them contain sugar) and eat the real thing. Full fat dairy - butter, yogurt, cheese, cream. Plenty of eggs. Avocados, olives, real mayonnaise on salads or olive oil, plenty of fish - oily fish such as salmon. Any meat.
Eggs are very useful because we can eat them at any meal, cooked any which way. We can have omelettes with cheese, mushrooms, bacon. What about a good fry up (eggs, bacon, mushrooms, a tomato, a high meat content sausage). If she likes salads, add some protein such as a steak, or chops, or a tin of salmon/tuna/mackerel. I enjoy an egg mayonnaise salad with 2 eggs and a generous helping of Hellmans Real Mayo.