Some people's bodies burn calories faster when dieting, while others slow down their metabolism to conserve energy.

“Researchers in 2019 discovered that most people's metabolisms fall into one of two categories. The first is what researchers call a spend thrift metabolism. People in this group, when their calories are restricted, their metabolism stays high and they continue dropping weight. However, the second group is what researchers label a thrifting metabolism. And when this group was placed in the same deficit, their bodies adapted to reduce their calorie burn and slow their weight loss to a crawl.”