Mostly a balance between slow and fast digestive food will (in time) will make the burps and farts go away. Avoid eating carbs without combining it with high fiber food. Generally speaking plenty of vegetables and little processed carbs will go a long way. But as usual it is personal what works best. Avoid processed food and sour dough bread
Another thing is how bad the state of a person's microbiome has become during a period of having a certain excess weight.
Unfortunately the microbiome gets in a state where it takes years and years to become somewhat healthy again once it has been disrupted.