How "empty" is an empty stomach? Can't you eat milk and bananas on an empty stomach?

In daily life, some activities must be performed on an empty stomach.

For example, if you have a physical examination and blood test the next day, you are required to fast the night before until the blood test is completed; if you are sick and take medicine , some medicines also require you to take them on an empty stomach.

In addition, we have also heard some sayings that we need to avoid eating on an empty stomach, such as not eating persimmons, bananas and other foods on an empty stomach .

So, are these foods really not suitable for eating on an empty stomach? How long does it take to be considered an empty stomach if you don't eat? Let's take a look today.

01

How long without food is considered fasting?

We have many organs in our abdomen, and fasting usually refers to the stomach.

The stomach is the largest part of our digestive tract. Due to individual differences, the stomach capacity of an adult is about 1000-2000ml, and the stomach capacity is basically in a high emptying state when fasting .

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For example, the normal stomach capacity of an empty stomach is only about 50 ml, while the stomach capacity after eating can reach 1500-2000 ml. Moreover, when eating, it takes only about 5 minutes for food to enter the stomach and empty.

From the perspective of food, the factors that affect gastric emptying rate are not only the physical properties of food (such as particle size, viscosity, etc.), but also the chemical composition of food.

For example, liquid food empties faster than solid food, small particles empty faster than large pieces of food, sugars empty the fastest, proteins the second fastest, and fats the slowest.

Generally speaking, it takes about 4-6 hours for the stomach to completely empty itself after eating a mixed meal like our daily diet . However, due to the different types of food eaten and individual differences, it may take some people more than ten hours to completely empty their stomach.

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The guidelines for venous blood specimen collection in my country's health industry stipulate that fasting should be done for at least 8 hours, preferably 12-14 hours.

Some medicines need to be taken on an empty stomach and can be taken 0.5-1 hour before a meal or 2 hours after a meal.

Therefore, it is difficult to generalize how long it takes not to eat to be considered fasting.

02

What activities can be performed on an empty stomach?

It is usually necessary to fast before some medical tests.

On the one hand, some blood tests require fasting, such as blood sugar, blood lipids, liver function, etc.

Because the composition of our blood is relatively complex and is constantly changing with the body's metabolism.

When the food we eat is processed by the digestive system, it affects the concentration of certain components in the blood, and it usually takes a long time (such as 6-8 hours) to return to the level before eating.

On the other hand, some digestive endoscopy or abdominal ultrasound examinations also require fasting, such as gastroscopy, colonoscopy, B-ultrasound, etc.

Moreover, some medicines need to be taken on an empty stomach, mainly to avoid the effect of food on drug absorption and bioavailability, and some may also be affected by gastric acid.

03

Is there any basis for the foods that cannot be eaten on an empty stomach?

1. Milk

It's not that everyone cannot drink milk on an empty stomach. It's just that for a small number of people who are lactose intolerant, drinking milk on an empty stomach will indeed cause nausea, vomiting, diarrhea and other physical discomfort.

However, if you eat some steamed bread, bread or other food before drinking milk and drink it in small amounts several times, the symptoms will be alleviated, and even after a period of time, the lactase activity will be activated, and you will be able to recover to the state where you can drink milk on an empty stomach.

However, people with milk protein allergy need to avoid drinking milk and its products under any circumstances.

2. Persimmon

People who are concerned about whether persimmons can be eaten on an empty stomach are mainly worried about the effects of tannins (the source of astringency), such as the risk of causing stones.

In fact, in order to attract consumers, persimmons sold on the market are generally de-astringent, such as with warm water or carbon dioxide.

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Moreover, there are 1,058 varieties of persimmons in our country, and the tannic acid content in different varieties of persimmons varies greatly. The tannic acid content in persimmons with high maturity tends to be lower.

Therefore, most of the persimmons we buy are highly mature persimmons, which do not contain high levels of tannin. Just be careful not to eat too much at one time.

3. Banana

Bananas are rich in potassium and magnesium, but our bodies do not absorb all of these nutrients at once.

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Moreover, the amount absorbed is limited. Coupled with the body's self-regulating function, as long as there is no special disease (such as kidney disease), there is not much risk in eating a moderate amount of bananas on an empty stomach.

04

What activities should be avoided on an empty stomach?

1. Take a bath on an empty stomach

Some people like to take a hot bath before going to bed. If it is too long after a meal, hypoglycemia, fainting and other phenomena may occur, especially for the elderly.

Therefore, do not take a bath too long after a meal, and avoid taking a bath on an empty stomach.

2. Donate blood on an empty stomach

Please note that you cannot be on an empty stomach before donating blood to avoid symptoms of hypoglycemia such as weakness, palpitations, and sweating.

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3. Exercise on an empty stomach

Some people who want to lose weight like to exercise on an empty stomach. Although the effect seems to be more obvious, doing so for a long time is not good for physical and mental health, and it is not advisable to do a large amount of exercise.

In summary

How long does it take to be considered fasting without eating?

Can't generalize

Basically close to the dining area

Or it is a long time after the meal

More suitable for fasting state

Usually before doing some medical examinations

Need to keep empty stomach

Author: Zhang Zhaomin, Master of Food Science, Senior Engineer

Review | Pa Li Ze, Chief Physician of Nutrition, former Deputy Director of the Chronic Disease Prevention and Health Management Institute of the Xinjiang Uygur Autonomous Region Center for Disease Control and Prevention

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