A recent study published in Science assessed how changes in body fat affect the risk for age-related macular degeneration (AMD), including the impact that a history of obesity can have even after weight loss.
Give me some background first.
Environmental and genetic factors are known to play major roles in the development of AMD. Research has determined obesity to be the second-leading (after smoking) genetic risk factor for late AMD. (via)
Talk about the study.
Researchers conducted a 20-week assessment on male mice: a portion were fed a high-fat diet for 11 weeks followed by a regular diet for 9 weeks; control mice were fed a regular diet for 20 weeks straight .
After 11 weeks on a high-fat diet, the mice gained three times more weight than the mice that followed a regular diet for the same time period. Interestingly, after the initial high-fat diet mice switched to a regular diet for 6 weeks, their weight dropped to the same as the mice who followed a regular diet for the entire study period.
Researchers also noted that the metabolic measures (insulin and glucose tolerance) of the initial high-fat diet mice matched the regular-diet mice by the end of the entire study period. (via)
Following the 20-week period, investigators assessed the choroidal neovascularization (CNV)—present in over 80% of AMD cases—in both mice groups. The initial high-fat diet mice showed a CNV that was 40% more than the regular diet mice.
Fat tissue was also measured in both groups; the investigators found that, despite the high-fat diet mice having the same metabolic measures as the regular-diet mice, the higher-fat diet mice had fat tissue that had properties leading to an increased AMD risk.
Researchers noted that the study, conducted using a mouse model, still needs to be tested and translated to humans. Also of importance: the studied mice did not have AMD. Instead, they had a laser directed at their retina that induced similar damage to that seen in macular degeneration.
A more precise animal model of AMD and human studies should be utilized in order to attain an accurate understanding of the connection between obesity and macular degeneration risk.