Why are some food with lower calories make our stomatch feels fuller than others with higher calories?

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For example, i feel so full after eating just a bit of sweet potatoes, but can’t get enough with the original potatoes!

In: Biology

Calories don’t equate to fullness. The sensation of fullness is a complicated mechanism that’s not fully understood, but it’s primarily believed to be driven by intake of protein, dietary fibre, and fat.

In your example, sweet potatoes have more protein and dietary fibre than regular potatoes.

Generally, we feel full when our stomach is full of food. Fibre fills up the stomach but doesn’t really have much calories so makes us feel fuller. (vegetables have alot of fibre)

There are however foods that ‘hack’ our fullness mechanism. For example, food that are rich in both fat and sugar (at roughly 50/50 ratio) stop us from feeling full so we eat alot more calories before we feel full.

So most ‘bingeable’ foods are those that have a 50/50 fat and carbs content (ice cream, cakes, donuts, pizza, crisps etc

Fat or carbs on their own don’t do this and we feel full quickly after eating them separately.

The combination of fat and carbs in modern foods is supposed to be one of the biggest contributing factors to the obesity epidemic.

Fullness is somewhat to do with leptin which is released from fat cells and regulates energy intake from within the hypothalamus. Depending on the energy source you experience fullness typically in a normal BMI we tend to feel full after eating a very high protein intake, carbohydrate intake and to a surprise of some a singular high fat intake. These systems on there own work well anyone will tell you who attempts a steak eat challenge. The problem is when suger a simple carbohydrate and fat come together as with processed and fast foods these foods activate the reward system heavily, are tasty enough it overrides the full mechanism regardless of calories leading to an increase in fat cells over time for example not feeling full after a big mac, the more fat cells you have the more resistance you have to leptin and insulin so not only do you feel less full your metabolism is slowed and it can become a spiral into obesity.

There’s an attribute for food, measured on a scale known as the [Satiety Index](http://www.mendosa.com/satiety.htm). It’s not strictly correlated to number of calories. Doesn’t quite answer the ‘why’, I admit, but it does show that calories aren’t the way to measure satiety, in general. (At least when comparing 100 calories of one food to 100 calories of another.)