There are frequent situations when a protruding abdomen can cause an excess of air, gas, and pressure within the abdomen, resulting in a visual presentation of a stomach that sticks out, but isn’t necessarily ” belly fat”.
To expand upon this, there are two main types of this:
A “Beer Belly”
where the abdomen is pushed out as a whole unit. These are usually wide infrasternal individuals who cannot expand their ribcage, so air (being a gas) follows the path of least resistance into the abdomen and results in a poor belly breathing pattern.
A “Pooch Belly”
This situation involves an even more descended diaphragm, where the diaphragm is so descended and contracted that it leads to a hyper-inflated state in the ribcage. This causes the diapgragm to change it’s line of pull on the abdomen and suck it inward and upward.
Read this article by De Troyer, 2016 for more.
This is not necessarily a bad thing, unless there is pain or loss of range of motion involved due to a poor breathing pattern.
Both cases are usually stuck in a degree of anterior pelvic tilt which pushes their abdomen out to some degree. Therefore, activating the hamstrings will be beneficial in both cases to allow for a more “neutral” pelvic orientation.
These individuals usually are compressed from front-to-back, needing a position where gravity can help compress them from side-to-side to allow for better expansion front-to-back. These people will feel much better in a sidelying breathing position.
These people are the inverse. They’re compressed from side-to-side and generally narrow infrasternal angled individuals. They will benefit from being in a quadruped or supine position to allow them to expand from side-to-side, as gravity acts downward to compress them front-to-back.