that study included margarine. (1968 - 73) and made it invaluable and irrelevant. I studied at the end of the 1970s when it was known that transfats metabolized worse than saturated fats. They were eventually taken off the market!
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6168703/
These are far more current and accepted:
https://pubmed.ncbi.nlm.nih.gov/27677368/
I love ghee. (but its just for the butter flavor! I am nondairy (inheriting a lactose and now casein problem!)
The one thing about taking nutritional chemistry was that it taught me how things digest. A dietician/nutritionalist learns more "trending" info. I learned the chemistry of the digestive process. That is still, after 50 years is still constant. The mechanisms of digestion. Fads/trends are removed. The body still operates best on a mixed diet of carb, protein, and fat. People do have metabolic issues requiring adjustment, and the American diet finds people consuming too much carb and simple sugar. But a balanced "Mediterranean" style diet is optimal for the "normal" person. Geriatric age nee higher protein levels than they used when younger and need to address the deterioration in digestive ability. Older people need to supplement as well and eat slower to masticate their food to grab all the nutrients possible. A low-carb diet "may be" detrimental if supplementation is not done for the loss of fiber, vitamins, and minerals found only in carbs/supplementation. I know quite a few people who thought the Keto diet was a magic bullet only to find out it backfired as they put on unhealthy weight and raised lipid/glucose levels! As an older person who no longer has muscularity and works outdoors, I rely on those carbs to "hold water" as opposed to the proteins and fats which release water during digestion and cause dehydration!