I'd say it is hunger. And cravings. Also our body adapts to diets and weight-loss tends to plateau.
3 simple tips I used when the above happened:
- Eat a good breakfast. A heavy whipping cream omelette and bacon has worked best for me. Keeps me full late into the afternoon.
- Follow the 80/20 rule. Eat "right" 80% of the time and indulge 20% of the time. I had some ice-cream or other treat on the weekend. Keeps you sane and it's easier to stay motivated. Nobody likes to feel like their "life is over" and they will never be able to eat what they like the most again. Just don't go overboard, all in moderation.
- When and if you plateau in your weight-loss, the body needs a wake-up call. When I first started with Low Carb High Fat, I plateaued after about 2.5 months. I did some research and decided to do the opposite of what I was doing. So for 3-4 days, I ate nothing but High Carb food, pasta, potatoes, sugar and so on. Then back to Low Carb High Fat. It worked. I started losing weight again.