Most people are familiar with the basics about calories: Calories are the fuel on which the body is run, unused calories get converted into fat, and too many stored calories is what leads to the belly paunch that few people love. There are, however, other details about calories that are not common knowledge. For instance, how soon are calories absorbed after eating? The answer to that question will depend on several factors.
Your Current Activity
Different activities require different amount of calories. The rate at which your body absorbs calories will depend on what you're doing. For instance, if you go for a walk shortly after a meal, you'll find that your meal is digested a lot more quickly. That's because walking increases your body's metabolism, which in turn affects the rate at which your body coverts what you've eaten. It's why your food takes longer to digest when you go for a nap afterward.
The Meal You've Just Eaten
Some meals are digested a lot more quickly than others. In fact, some meals are digested too quickly. It's one of the primary reasons dieticians argue so strongly against overindulging in processed meals. Foods that have been made out of white flour, for example, contain very little fiber content. Your body will therefore find it a lot easier to break it down and absorb the calories often within minutes. This usually leaves with the body of a surplus of calories, which inevitably gets converted into fat.
On the other hand, it takes a lot longer for your body to convert foods that contain whole-grain fiber because the foods will first need to be broken down into simpler compounds. This gives you enough time to burn of the calories in your blood stream and prevents the risk of you gaining fat.
The older you get, the slower your digestive process becomes. This is because most people tend to lose their overall muscle tone as they age. This reduces the amount of calories that your body needs during the day. It is why young people are seemingly able to rip through meals without any visible effect. You can, however, counter the effect by engaging in resistance exercise to replace your lost muscle.
Because men tend to have more muscles and less body fat than their female counterparts, their metabolic rate is usually higher. They are therefore able to absorb and use up calories at slightly faster rate than women of the same age.