Gaining a considerable amount of weight after one meal, is that possible?

Many of us will probably recognize the feeling: the guilt after indulging in a hearty meal during a cozy evening, thinking you've gained a whole kilo...

The next morning, the scale and the mirror confirm your negative feelings. You're certain that the enjoyable evening resulted in significant weight gain.

Do you want to know if the extra weight you've gained is actually fat? Maybe you don't need to feel as bad as you think. Read along with us below.

What causes weight gain?

While weight loss involves losing fat through a negative energy balance, weight gain, in most cases, occurs due to a surplus of calories: a positive energy balance. This means you consume more calories than your body expends.

How many calories is 1 kilogram of fat? 

To gain 1 kilogram in fat, you need to consume an excess of 9,000 calories. This is because 1 gram of fat contains 9 calories.

Our body fat mass is not composed of 100% fat but rather 87%. This means that approximately 7,830 calories are stored in 1 kilogram of fat.

Achieving a surplus of 7,830 calories with a single meal is practically impossible. Additionally, you might question whether your body can effectively absorb and store these extra 7,830 calories.

What else should we consider?

Our body needs to burn and expend energy to process food, a process known as thermogenesis. We must subtract the number of calories your body burns to process food from the initial 7,830 calories.

The most commonly used form of thermogenesis is diet-induced thermogenesis (DIT).

DIT accounts for roughly 10% of our calorie intake. The composition of food also plays a crucial role. For example, the DIT for fat is 0-3%, for carbohydrates 5-10%, and for protein 20-30% of the energy provided by the macronutrient (1).

"Do my mirror and scale disagree then?"

No! Glycogen and water also play a role, and we haven't discussed them yet.

Before your body converts carbohydrates into fat, it first wants to replenish the glycogen stores in the body. Your body primarily stores this in your liver and muscles.

Each gram of glycogen stored in the liver binds to 2.4 grams of water. When our liver is full of glycogen, it weighs about 290-430 grams more for men and 240-365 grams more for women than when the glycogen supply is depleted.

And then we have our muscles. They also store glycogen and water, the amount of which depends on various factors, including the amount of muscle mass.

Men can store an estimated 250-465 grams of glycogen in the muscles, and women can store 175-350 grams. This, in turn, binds to water. In the muscles, 1 gram of glycogen binds to at least 3 grams of water.

As you can see, this can lead to a significant increase in weight.

Often, large and unhealthy meals are rich in salt. Salt causes your body to retain extra water. So, if you've had a hearty salty meal, you might retain even more water and gain more weight.

Let's not forget your stomach

The large meal you've eaten doesn't just disappear. This meal is still (partly) in your body the next day and is also partly responsible for the weight gain. 

Conclusion