If you are struggling to lose weight and you don’t track what you eat, Occam’s razor suggests that you are likely eating more than you think. People underestimate their calorie intake by an average of 10–20%. This can be as high as 50% in people who think their metabolism is broken. Why you are overeating is another question entirely.
In short, read the ingredient label of your favorite high-fiber protein bar. If it uses isomalto-oligosaccharides (IMOs), then it is best avoided. The FDA has ruled that IMOs have insufficient evidence to be claimed as a dietary fiber, and a handful of studies suggest that they are absorbed with similar efficiency as sugar.