I would suggest two things.
A popular product in the stores right now is called “Kefir”, and it is like a yoghurt smoothie, but only about 110 calories a cup for unflavored (130 for fruit flavored). However, it has about 10 different kinds of probiotic bacteria in it, so you get a wide assortment instead of just a few.
The other thing is the generic version of ‘Pearls’, which are two kinds of probiotic bacteria that are enteric coated, so they make it through the harsh environment of the stomach before being released.
Many people incorrectly assume that bacteria cannot make it through the stomach alive, but while many are attrited, a goodly number make it through.
When someone first starts consuming Kefir, I recommend they take it slow, because it can result in some “bacteria battles” and result in gas or discomfort at first. It takes about two weeks for the gut to get acclimated, and about a month to start seriously changing the bacterial balance of the gut.
A rather new discovery is that people who are extremely obese have just one genus of bacteria occupying almost one third of their floral space. It is the enterobacter genus, and its toxin is known to cause fatty weight gain.
http://en.wikipedia.org/wiki/Enterobacter
A study put extremely obese people on an anti-enterobacter diet and they dropped about 1/3rd of their overweight without any exercise.
That last is very, very interesting.
There is so much we don’t know about nutrition and health, and there is so much agenda-laden “research” that it is hard to tell what to believe. Even for someone with a strong science/technology background.