Q: This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.
It is considered that overeating and lack of muscle tone is the main cause of a beer belly, rather than beer consumption. A 2004 study, however, found a link between binge drinking and a beer belly. But with most overconsumption, it is more a problem of improper exercise and overconsumption of carbohydrates than the product itself. Several diet books quote beer as having an undesirably high glycemic index of 110, the same as maltose; however, the maltose in beer undergoes metabolism by yeast during fermentation so that beer consists mostly of water, hop oils and only trace amounts of sugars, including maltose.
A:
In addition to a lack of muscle tone, what is believed to be the main cause of the beer belly?