it's written by dietician fuhrman. >> reporter: it's that time of year when we're hoping a change ofwhen it comes to belly bloat. >> our systems work a little bit differently, and not every nutritious food will feel good in every person's body. >> reporter: author of the new book "the bloated belly whisperer" says there are common mistakes we all make during meal times, especially when it comes to choosing foods for digestive health. we have serial and oatmeal here in front of us. why is that? >> some fiber cereals will add these special types of fibers to boost their numbers. that can be fermentable and cause gas in the gut. >> reporter: and an alternative to high fiber cereal? >> oatmeal. the texture is less like roughage. something more healthy. >> reporter: looking at lunch versions here, we two versions of kale. why is that? >> as your stomach is trying to current that coarse, big bole of kale into kale smoothie in your stomach, it is creating a lot of acid, a lot of churning and some people can experience that as reflux. when you put it in a soup form, it's chopped up really, r