As men age, they're more likely to develop big bellies. After age 40, the natural reduction in testosterone means excess calories are often stored as visceral fat. Aging also makes you naturally lose muscle mass. Muscle keeps your metabolism burning at a solid rate. When you lose this muscle -- about 1 pound per year after age 30 -- your metabolism declines, and it becomes easier to gain fat, which often goes straight to the belly in men.
First one’s the Adrenal belly or Adrenal shape, caused by increased levels of cortisol. When going through stressful periods, the production of cortisol increases, and this favours the accumulation of fat around the waist, leading to a saggy abdomen. Both men and women are likely to gain weight around the waist if they are constantly exposed to high levels of stress, and besides the excess belly fat, they are also likely to experience fatigue, back pain, nervousness, poor memory and sleep problems.