Complex sentence: Some research suggests this causes body fat to be eliminated from the body, although this theory remains controversial, insofar as it refers to excretion of lipids (i.e., fat and oil) and not to fat metabolism during ketosis.
Split into simpler sentences: Some research suggests this causes body fat to be eliminated from the body. This theory is controversial, insofar as it refers to excretion of lipids (i.e., fat and oil) and not to fat metabolism during ketosis.