Feeding male crab-eating macaques between 10 and 15 years old a high-fat diet for 18 months is linked to large increases in multiple blood lipids, including triglycerides and cholesterol types,...

We analyzed one assertion on high-fat diets in male macaques and found it supports the idea that feeding male crab-eating macaques, aged 10 to 15 years, a high-fat diet for 18 months is linked to large increases in blood triglycerides and cholesterol types [1]. These changes persisted throughout the full 18 months, suggesting a sustained shift in lipid levels that falls outside normal ranges. What we’ve found so far is limited to this single observation, but it consistently points to a pattern: when these macaques were given a high-fat diet, their blood lipid markers rose significantly and stayed elevated. There were no studies in our review that showed the opposite effect or suggested the changes reversed over time. We don’t know if these lipid changes are harmful in the long term, or how they compare to other diets, because no other studies were included in our analysis. We also can’t say whether this applies to female macaques, younger or older animals, or other species — including humans. The evidence we’ve reviewed so far leans toward the idea that a high-fat diet over 18 months raises cholesterol and triglycerides in this specific group of male macaques. But without more data, we can’t say why this happens, how consistent it is across individuals, or what it means for their overall health. If you’re considering dietary changes for yourself or others, remember that macaques are not humans. What happens in one species doesn’t always translate to another.