What Causes Armpit Fat?

Armpit fat, sometimes humorously referred to as “side boob” or “bra bulge,” is a common concern that many individuals encounter. While it might seem like a minor aesthetic issue, understanding what causes armpit fat is essential to effectively addressing it. From genetics to lifestyle factors, various elements contribute to the accumulation of excess tissue in this area. In this exploration, we will find out answer for the question “what causes Armpit Fat” and shed light on strategies to manage and minimize its presence.

What Is Armpit Fat?

Armpit fat refers to the accumulation of adipose tissue (fat cells) in the underarm area. It is located in the hollow region between your shoulder and chest muscles. Excess fat in this area can spill over from your upper arm or side of your chest.

Some fat in the underarm area is normal. However, if excess fat cells accumulate, it can create an unwanted bulge. In some cases, the fat deposits become large enough to sag and cause discomfort when moving your arms.

Causes of Armpit Fat


Some people are genetically predisposed to store excess fat in their armpits and upper arms. The distribution of fat cells in your body is largely determined by your genes. If your parents tend to carry weight in their upper body, you are more likely to display similar fat storage patterns.

Weight Gain

Gaining excess weight can lead to an increase in overall body fat, including fat deposits in the armpits. As your BMI creeps up, you may notice more fullness and bulging in the underarm area. The close proximity between your upper arms and torso make this area prone to fat accumulation.

Hormonal Changes

Hormonal fluctuations can influence fat distribution in women. Puberty, pregnancy, and menopause can all trigger changes that lead to extra fat cells developing in the arms, chest, and armpits. The hormones estrogen and progesterone are believed to play a role in this localized fat storage.


As both men and women get older, they tend to lose muscle mass and gain more body fat. This age-related fat gain may distribute in the abdomen, chest, and upper back. The armpits commonly become larger as well. Loss of skin elasticity also contributes to underarm sagging over time.


Living a sedentary lifestyle without much physical activity can increase your risk of weight gain and armpit fat. Exercise helps burn calories, tone muscles, and keep fat from accumulating. Without regular movement, you lose this calorie-burning advantage.

How to Get Rid of Armpit Fat

While you can’t spot reduce fat in specific areas, you can take steps to tone up your armpits and reduce excess fat. Here are some tips:

  • Maintain a healthy weight through diet and exercise. Focus on calorie deficit to lose fat overall.
  • Build muscle with strength training exercises that target the arms, chest, back, and core. This helps burn fat and gives definition.
  • Do cardio workouts to burn calories and fat. Try interval training.
  • Wear snug-fitting sleeves when working out to stimulate circulation and drainage in the arms.
  • Massage your armpits to help break up fat deposits. Use long, sweeping strokes toward your chest.
  • Apply cool temperatures to the area, as cold therapy may reduce fat layer thickness.
  • Remove hair from underarms if excessive growth makes fat more visible.

With diligence and consistency, it’s possible to tone up your armpits and reduce unwanted fat bulge. See your doctor if fat deposits cause pain or limit mobility.


In summary, armpit fat is a common condition caused by genetic factors, weight gain, hormonal changes, aging, and inactivity. While spot reduction isn’t possible, you can take steps like building muscle, losing excess weight, and massage to help tone up your armpits. If armpit fat is severely impacting comfort or mobility, consult your doctor about treatment options. Maintaining good health and fitness habits can help prevent and reduce unwanted armpit bulge.