If a food is said to have 100kcal do we get all of those?

Question

If a banana is said to have 100kcal and you and I eat it are we going to get:

1. all of those calories?

2. the same amount of energy or it varies person to person?

In: Biology

Answer 1

It’s how much energy is in the food and not how much your body gets out of them. Here’s how they calculate calories:

The calorie content of food is measured in kilocalories (kcals), which is the amount of energy needed to raise 1 kilogram of water 1 degree Celsius.

A sample of food is placed in a sealed container filled with oxygen and surrounded by water. The food is ignited and the temperature increase of the water is measured to calculate the calorie content. This method is called direct calorimeter.

Now this process isn’t at all how our bodies process food. We use energy to break things down, some stuff can only get absorbed if other things are also present, lots of processing is dependent on the bacteria in your digestive tract and what kind of bacteria it is, etc…. So many factors determine what and how much your body can extract from food.

There are even plenty of foods that are considered negative calories in terms of what the body gains from digesting them as it takes so much energy to break them down. You may loose total calories eating them but gain lots of nutrients.

(Below stolen from Google AI search)

“Negative calorie” foods are foods that require more calories to digest than they contain, resulting in a net negative calorie intake. Some examples of negative calorie foods include:

Cucumbers
High in vitamins, minerals, and electrolytes, and contain around 16 calories per 100 grams.

Celery
Low on the glycemic index, meaning it has a slow, steady effect on blood sugar.

Broccoli
One cup of broccoli contains just 25 calories, but requires up to 80 calories to digest.

Apples
Contain very few calories, with 100 grams of apples containing only 50 calories.

Watermelon
94 percent of the weight in watermelon is water.

Lettuce
Contains only 5 calories per 100 grams, and has essential nutrients like vitamin C, iron, and calcium.