The weather is hot, and many people like to eat cold food and enjoy the refreshing feeling on the tip of the tongue.
Many health professionals don’t recommend this, they say, don’t let your body warm up with cold food. This consumes energy, affects digestion, and can damage health, especially for the infirm.
A popular science writer said that after drinking a glass of ice water, it only takes a few minutes for the contents of the stomach to return to normal body temperature, which is not a big problem.
But there is also news recently that a 19-year-old boy drank a lot of ice water after sweating during the summer, resulting in a myocardial infarction. He was not rescued and left this place forever. world.
1 Are there health risks to eating cold food?
A few minutes may not seem like a long time, but a few minutes of ischemia in the heart can be deadly enough. Humans also have to follow the physical laws of “heat expansion and cold contraction”. Exercising in summer will increase the burden on the cardiovascular system. A lot of sweating will lead to blood concentration and blood viscosity. In addition, drinking a lot of ice water will cause the blood vessels to shrink due to sudden cooling near the cardiovascular system, which may cause plaques to fall off and block the blood vessels. May cause vasospasm and insufficient blood supply.
Some people who are prone to headaches may experience headaches after drinking ice water, which may also be related to the contraction of blood vessels. People with irritable bowel syndrome, chronic enteritis, and chronic gastritis may experience abdominal pain, diarrhea, bloating and other conditions due to sensitivity to cold stimuli. Patients with gallbladder disease and nephrolithiasis may also have acute exacerbations due to cold cramps in the gastrointestinal tract. Therefore, it is better for people who are weak and sick not to challenge their physical abilities.
People with pre-existing diabetes, cardiovascular disease, cerebrovascular disease, etc. need to be more careful. It is better to consume water and food at room temperature or close to body temperature, which is safer.
Of course, most people don’t suddenly pour ice water, but slowly enjoy cold sweets such as sorbet, ice cream, smoothie, etc. When eating frozen desserts and drinking iced beverages every day, be sure to slow down, take small sips, and stop after a few sips. Because eating is slow, food can gradually heat up as it enters the mouth and digestive tract, so it is generally not dangerous.
Some people open their minds because of this: Since eating cold food, you need to use the body’s heat to warm it up. Isn’t that a good thing? You can lose weight by burning calories in your body! For example, drinking a glass of ice water can consume several thousand calories…
2 Can drinking an iced drink in summer help you lose weight?
Use middle school physics knowledge to figure it out.
It takes 1 calorie to warm 1 gram of water by 1 degree.
You drink 200 ml of 0 degree ice water and warm it up to 37 degrees Celsius of body temperature. The calories you need = 200*37 calories = 7400 calories = 7.4 kcal.
Please note that food energy is kcal, 1 gram of fat = 9 kcal. The unit of heating physical calculation is the card, which is a thousand times worse!
1 gram of fat has 9 kcal of energy and 1 gram of sugar has 4 kcal of energy. Therefore, after drinking this glass of ice water, the extra calories consumed cannot even consume 2 grams of sugar or 1 gram of fat.
According to my country’s nutrient supply standards, the daily calorie intake of light-weight adults is 1800 kcal for women and 2250 kcal for men. The energy consumption caused by the temperature change of several kilocalories is really negligible.
If you don’t sweat too much, you need to drink 7-8 glasses of water a day. Even if you drink all ice water, you will consume about 50 kcal of calories. However, a 200-gram cup of sweetened beverages usually contains 20 grams of sugar, which contains 80 kcal of energy.
It can be seen that drinking seven or eight glasses of ice water in a day, relying on its “coldness”, is not enough to consume the energy in a cup of sweet drink. What’s more, many people drink several bottles of iced sweet drinks instead of iced mineral water. Drink more than 100 grams of sugar a day! Rather than drinking cold drinks to lose weight, it is better to drink sweet drinks to gain weight!
As for all kinds of sugary and fat iced milk tea, ice cream, ice cream, etc., do you think you can lose weight?
So it doesn’t make sense to eat cold food with the goal of burning extra calories.
So, is it useful for relieving the heat?
In comparison, the human body loses more heat by sweating. It takes 574 calories to completely evaporate 1 gram of water into steam at 37°C. If 200 grams of water is turned into sweat and evaporated, it will consume a total of 114,800 calories, or 114.8 kilocalories.
The problem is that drinking cold fluids constricts blood vessels and reduces sweating. After drinking fluids slightly above body temperature, sweating increases. Therefore, drinking iced beverages does not help the human body to increase heat dissipation and reduce body temperature.
3 If you eat the main food after it is cold, will it reduce the amount of calories your body gets?
The logic of this statement is: after it is left cold, it will be difficult to digest, and if it is not digested, the body will get less calories.
Indeed, for starchy foods, some resistant starch will be produced due to the effect of “rejuvenation” after cooking and then cooling.
Resistant starch cannot be digested and absorbed in the small intestine. After entering the large intestine, it is fermented by microorganisms to produce short-chain fatty acids such as propionic acid and butyric acid, which can be partially utilized by the human body. Therefore, its caloric value is much lower than digestible starch.
However,How much resistant starch can be produced after cooling? It depends on the proportion of amylose in starch. Amylose is easy to be aged and retrograded after cooling, while amylopectin is difficult to be aged and retrograded, and hardly produces resistant starch. So, the higher the amylose content, the greater the potential for resistant starch.
Therefore, the high-amylose varieties have poor scores in the “cold rice texture” item. A little cold is dry and hard, difficult to chew, and difficult to digest. In agricultural production, in order to improve the quality of grains, varieties with less amylose are usually preferred.
For example, corn sold in cafeterias is soft and tasty for several hours after cooking because they are waxy corn with very low amylose content. High amylose corn is generally used to make industrial starch.
However, in recent years, in order to reduce the caloric value of food, some foods have deliberately added resistant starch made from high amylose ingredients to make foods such as biscuits and snacks to provide food to people who need it. Weight loss and blood sugar control consumers. There are also breeders who have developed some high-amylose rice varieties, which are sold under the names of “Low Sugar Rice”, “Wantang Rice” and “Utang Rice”. However, because their taste is really not as good as ordinary rice, especially when eaten after cooling, the stomach will feel uncomfortable, so except for diabetics and dieters, other people are not likely to want to eat this. of the category variety.
If you eat a low-amylose variety of food, such as rice cooked with ordinary Northeastern rice, the calorie reduction from eating cold rice is not much, usually only 1% Several.
In short, the hope of reducing calorie intake by eating cold food to reduce digestibility is also unrealistic. Although the digestibility of cold rice and dry steamed bread will be slightly reduced, it will feel very uncomfortable. In the long run, if you eat gastrointestinal diseases, you will lose more than you gain.
4 Eat leftovers cold, beware of bacterial food poisoning
On the other hand, because of the gluttony for cold food, many people eat leftovers from the refrigerator without heating. All kinds of cold dishes are eaten in the refrigerator for several times. Days, also increase the risk of bacterial food poisoning.
The first thing to be sure is that being able to store food in the refrigerator itself in a timely manner is something to be commended. Summer is scorching hot and cooking is hard work, so it makes sense to make a meal and divide it into two or three portions immediately, refrigerate it immediately, and save it for the next meal or the next day. If frozen, it can be stored for at least a month.
Bacteria multiply more slowly and produce toxins more slowly when meals are kept in the refrigerator than at room temperature. For example, starchy foods such as porridge and noodles have a risk of developing Staphylococcus aureus toxins for 4 hours at room temperature, and the same risk for more than ten days in the refrigerator. Pathogens such as botulinum toxin can also be significantly slowed down in the freezer.
However, after all, the refrigerator is not a safe, and some low temperature-resistant pathogenic bacteria will still be active in the refrigerator. For example, Vibrio parahaemolyticus, Listeria monocytogenes, etc., still have the ability to cause disease after being stored in the refrigerator. Therefore, for safety reasons, refrigerated meals, as well as prepared meals, should be reheated to a core temperature of more than 70 degrees after they are taken out, in order to kill most of the live bacteria.
What’s more worrying is that some people don’t refrigerate immediately after cooking, but let it sit at room temperature for two or three hours before remembering to put it in the refrigerator. That way, the bacteria have enough time to thrive at room temperature. If you take it out of the refrigerator without sterilization, and continue to leave it for one or two hours before eating, it will even reach a dangerous number of bacteria and even the danger of bacterial toxins.
Although the human body has resistance, it is not necessary to constantly test the antibacterial ability of your digestive tract.
Especially those cold dishes, cooked meats, etc., should be taken out once and eaten as a meal, and do not eat leftovers repeatedly, because they will not be reheated and sterilized before eating. Cold dishes can be mixed less at a time; cooked meat can be refrigerated for a few days, each time a small piece is cut and eaten, instead of taking it out and leaving it at room temperature for half a day, and the unfinished part is refrigerated, and tossing hot and cold repeatedly.
In short, In the heat of the heat, eating iced food won’t help, and it’s safer to eat food at room temperature or warm. Leftovers and cooked cold dishes stored in the refrigerated refrigerator must be heated and sterilized before eating to avoid unnecessary trouble for yourself and your family due to greed for cold food.
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Fan Zhihong_original nutritional information
Beijing Food Nutrition and Human Health Advanced Innovation Center Post Scientist
Director of Chinese Nutrition Society
Director of China Association of Health Promotion and Health Education
China Association for Science and Technology hires chief expert of nutrition science communication
PhD in Food Science, China Agricultural University