In healthy adult men, levels of free fatty acids and cortisol in the blood rise together at certain times after eating a high-fat meal, and these changes are statistically linked.

When healthy adult men eat a large mixed meal high in fat, their blood free fatty acid levels rise slowly and peak after 6 hours. When they eat a meal with 75 grams of pure fat, their free fatty acid levels rise faster, peak at 4 hours, and stay high at 6 hours. The type of fat in the meal affects when and how much free fatty acid appears in the blood.

After eating different types of meals, healthy adult men show different patterns in cortisol levels over time: glucose causes a temporary rise followed by a drop below normal, while protein and fructose cause a steady decline over several hours, suggesting that the type of nutrient affects cortisol dynamics differently.

After eating a meal with both fat and other nutrients, cortisol levels in healthy men drop to their lowest point at 4 hours and stay low for 6 hours. After eating a meal with only fat, cortisol drops faster—to its lowest point at 2 hours—and stays low for the full 6 hours. The timing and duration of cortisol suppression differ based on the type of fat-containing meal consumed.

When healthy young men only eat between noon and 8pm for five days straight, it doesn't change how their free fatty acid levels respond after eating a high-fat meal

After eating meals containing only sugars like glucose and fructose—without any fat—healthy adult men experience a sustained drop in free fatty acids in their blood for up to six hours, primarily due to insulin reducing fat breakdown rather than sugars being converted into fat.