Belly fat is insulin resistance
Weight gain is dysfunction. Fix that dysfunction and the excess weight comes off.
Belly fat could be the dangerous form of excess weight known as visceral that's linked to obesity, chronic inflammation, insulin resistance, heart disease, cancer, oestrogen dominance, mood imbalances and even dementia.
Visceral fat is gel-like, and it's intra-abdominal, surrounding your organs like your liver, kidneys and pancreas.
Subcutaneous fat, on the other hand, is the belly fat you can see and touch around your middle. It can be stubborn and hard to lose.
Too much visceral fat can interfere with organ function, trigger inflammation, and confuse your hormones causing faulty hunger signals and brain function, and weight gain.
Too much subcutaneous fat shares some of this dysfunction, but to a far lesser extent.
What causes visceral fat?
Often blood sugar dysregulation.
In short you eat too much sugar for your body, including refined carbs like bread and pasta, until your cells can't accept any more glucose and refuse insulin, the hormone responsible for carrying glucose into your cells.
The excess glucose has to go somewhere so your body stores it as fat, at first away from your organs, but in time as visceral fat.
If you're weight loss resistant because of the inflammatory nature of any belly fat, you could find this hard to lose. Calorie restriction and exercise alone may not be enough.
Instead you might need to
Change your ratio of carbs to fat and protein, fast
Reduce inflammatory foods especially sugar and refined carbs, but often gluten, soy and dairy
Fast, but according to your needs and monthly cycle if you're a woman
Detox your liver
Fix your thyroid if it's too slow or even fast
Restore gut health, which is intimately involved in blood sugar regulation, metabolism (energy), and hormones