How come weight is affected by calories, and not the weight of the food? If I eat a bag of candy, I will gain weight, but if I eat 4 apples, I won’t gain as much?


How come weight is affected by calories, and not the weight of the food? If I eat a bag of candy, I will gain weight, but if I eat 4 apples, I won’t gain as much?

In: Biology

You excrete the mass of the object after you consume it. When you drink a litre/kilogram of water, you will initially show a kilogram heavier on the scale. However, you will eventually piss out, sweat, exhale, etc. that water and return to the weight that you were at before. Drinking water isn’t “true” weight gain because it is a temporary change.

Body mass is gain from calories, and calories alone. If you eat more calories than you burn, those calories convert to fat and store within your body for use at a later time. Apples have less calories per weight than candy. When you eat apples, you will end up excrete most of that weight right back out.

Organisms have different abilities to extract useful energy from food. Cows, for example, can extract more useable energy for grass than a person could. The actual weight comes from the mass of the ingredients not from their ability to be converted to usable energy by our bodies. Caloric density is a helpful concept. How many calories per gram. There are a lot of things in food (like water and fiber) that contribute to its weight but not it’s calories. You will gain weight in proportion to the usable calories you consume whether from apple or candy. 4 usable calories of apple is equal to 4 usable calories of candy.

A bag of candy is refined and processed sugar that has an energy density ratio that is off the charts. Sugar in general is very easily digested, often before it reaches even the stomach.

An apple on the other hand is mostly indigestible fiber. The bulk and majority will pass through your system and be expelled.

As far as I know, your body only processes fat, carbohydrates, protein, and alcohol for it’s calories. Fiber actually contains calories but your digestive system can’t process them, so you poop them out instead.

Fat and carbohydrates in particular, if not used immediately, end up being stored as fat, so they can be used for later.

I could go into how carbohydrates and fat are metabolized differently, but that might go a little paste the 5 year old range.

As far as apples are concerned, they contain some sugars, but the majority of their weight is water, which you pee out, and fiber, which you poop out.

I hope this answers your question. Feel free to ask for more clarification.

Calories measure the energy you can get from a food. When you eat something the energy, if not used up, is stored as fat or special forms of sugar.

If you take a pound of candy it has lots of calories since it’s mostly sugar, which gets stored up and causes weight gain.
If you take a pound of apples it has some calories from sugar, which can be stored up, but also water and fibre which end up as waste.

Apples are also healthier because they contain important vitamins and minerals, as opposed to the “empty calories” of candy which provide energy but no other nutritional value.

1lb candy = 1lb sugar
–> 1lb weight (stored energy)

1lb apples = 0.5lb sugar + 0.5lb water & fiber
–> 0.5lb weight (stored energy) + 0.5lb down the toilet

Our body doesn’t keep everything we eat.

When food passes through us, our digestive system filters all usable nutrients it can get out of the food you eat and keeps these in you. What is “usable” to our body changes with what your body needs at the moment. Children need plenty of special stuff to grow in large numbers like calcium for bones, iron and proteins for muscles.

We have a general need for other nutrients to keep our regular functions up, like vitamins, but what we always need plenty of is energy. Our body wants to take in as much energy as it can, there is basically no limit since before modern times, it was basically impossible for us to consume more energy than was unhealthy.

Any surplus energy that is not currently needed will be stored as fat, that way it adds weight to your body.

TL;DR Candy is mostly sugar and your body likes to keep sugar, apples contain a multitude of ingredients of which most just pass through you.

One thing missing from the explanations is that your weight will initially increase by the weight of what you have eaten.

But as you digest it the other explanations take over.