Why Does My Stomach Look Bigger if I Work Out?

It's not uncommon to experience a frustrating phenomenon when exercising: even with a regular workout routine, the stomach may distend and seem to get bigger over time. Figure out the root cause by examining the factors involved and then alter your behaviors or perceptions to minimize the bulge.

A close-up of people's mid-sections in an aerobics class. (Image: Huntstock/DisabilityImages/Getty Images)

Curb Your Appetite

Exercising doesn't automatically result in weight loss or a trimmer, tighter physique. Many people continue to gain weight over a period of regular exercise due to an increase in appetite. Eating more calories will result in gradual, consistent weight gain, and it's likely that many of those extra calories will show up around the midsection, especially as you age. You will need to eat steadily to support your workouts but not excessively.

Muscle Gains

People who incorporate core training or weightlifting into their exercise routines may experience some weight gain due to increased muscle mass. Although it's unlikely for that weight gain to show up in the form of a larger midsection, it is possible; as ACE Fitness notes, greater superficial muscle definition is one result of core workouts. Body changes will differ among individuals.


It's possible for people to perceive their stomachs as growing larger after exercise even if there is no physical change in size. Especially after starting a new workout routine, many people are hyper-vigilant about any changes in their body size or looks, and that increased awareness may result in them taking notice of a change that is not actually present. In some cases, a person's stomach may actually be growing trimmer and toner, but the changes are so gradual that they remain unnoticeable.

Down the Road

It's common for people to experience expanding belly fat or notice bigger waistlines as they age. Both women and men lose some lean muscle mass and gain body fat as they grow older and their metabolism slows. The clinic points out that as your body composition changes, it's possible to notice a bigger midsection even if you haven't gained any weight. Heredity and genetics may also play roles.


It's impossible to narrow down a single cause of an expanding belly because everyone's bodies and physical conditions are different. Before changing your diet or exercise program, talk with your doctor. Doing more vigorous aerobic exercises can help burn off extra weight around the midsection, and adding a regular routine of core moves to your workout can tighten stomach muscles. Perform the plank, the abdominal bridge, crunches and the quadruped because they tone multiple core muscles simultaneously.

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