Post count: 52 does not provide any references. It’s sad to see so many website pulling GI values from i-don’t-want-to-know-where!
If you look at the usual scientific sources you’ll see that yoghurt has been tested extensively, however, not natural, unsweetened, full-fat/whole yoghurt. Whereas, full-fat/whole milk has been tested a lot. IIRC, Norm uses a GI of 30 in his book (don’t have it at hand right now) which is a “conservative” value since several tests show even higher values. Now, yoghurt is generally easier on the stomach/intestines than plain milk (as explained in the FTD book). So, a higher GI seems to be justified. And some tests confirm this.
Sweetened yoghurt should have a higher GI simply because in general it is sweetened with table sugar which has a GI of 65%. If you look at the GI tests data, many show GIs greater than 36. There are also some with lower values. But without knowing the exact ingredients it’s rather pointless to speculate.
Fortunately, the GI of unsweetened yoghurt is less of an issue since full-fat yoghurt has only 5% or less carbs.