Apart from being sedentary, the thing your bum hates the most is dieting all the time!
Every time you follow a diet and then put back on the weight you lost, your body stores up fat ready for the next period of "fasting
And as you're a woman, your body doesn't just store it anywhere: it goes straight to your thighs and bum.
To prevent your bottom ballooning, you therefore need to avoid the yo-yo effect as much as possible.
From a food point of view, the best way to help lose weight from your bum area is to eat a diet that's low in fat and rich in protein which nourishes muscular mass.
You should also avoid sugary foods with a high glycemic index (fizzy drinks, sweets, pastries, etc.) that have the distinctive ability of being immediately stored in the form of fat cells.