Key Takeaways. Carb and fat blockers are substances that interfere with the digestions of carbohydrates and fats. There are no studies showing these supplements help you lose weight—they only help you limit fat gain while overeating.

Do fat blockers help you lose weight?

Key Takeaways. Carb and fat blockers are substances that interfere with the digestions of carbohydrates and fats. There are no studies showing these supplements help you lose weight—they only help you limit fat gain while overeating.

Are carb and fat blockers safe?

As far as side effects are concerned, carb blockers are considered very safe. However, when carbs are fermented by bacteria in the large intestine, the gasses they release can result in a number of uncomfortable side effects. These can include diarrhea, bloating, flatulence and cramping ( 1 , 5 ).