Everyone needs a different amount of energy to fuel their body for the activity they do each day. How much energy you need depends on a whole range of things such your gender, weight, your job, your training and whether you're trying to maintain, gain or lose weight.
It's actually far more complicated than some people would have you believe. It's the reason I have issues with generic templated meal plans, 28 day challenges and dieting apps - they don't take into account your personal circumstances or goals (other than in a really generic way).
Women in particular often sell themselves short when it comes to calories. When our life is busy and we're constantly being bombarded with the idea that we should be dieting at every moment, it's very easy to fall into the habit of not eating enough. Sometimes it's purposeful but, more often than not, it's unintentional.
I made that mistake myself last week. I had a few busy days, a night of restless sleeping and had done a bit of extra exercising. I (quite unintentionally) didn't eat very much during those days because I was busy and distracted and had stopped listening to my body's hunger cues. I felt fine for the first day but at the end of the second day I crashed. Hard. I was suddenly ravenous and I craved all of the sugar. I felt light-headed, irritable and nauseous. It took a full two days of eating properly and purposefully to feel better again.
The point is, we can all fall into the trap of less is more.
I see it so often with people who are trying to lose weight. They start an intense exercise regime and dramatically cut out calories at the same time according to some generic meal plan or weight loss guide they have picked up online, thinking they have done the right thing. What they haven't done is taken into account the extra energy their body is now using, or how difficult it will be to sustain high-level training without a whole lot of food.
A small energy deficit is ideal for weight loss. A larger deficit can lead to a whole bunch of problems if it's done without medical supervision.
Our body fuels itself on glucose and so when it's short on fuel our body wants it in its purest form. Fast. Now. That, of course, ends up being chocolate or some other sugar-laden goody. It's why crash diets often end in binge eating. It's why low calorie diets are very hard to maintain in the long-term. It's not about self-control or addiction. It's science.
You need to know how much your body needs and then you need to provide it in the best way possible.