How many friends have tried the “Cold Rice Diet”?
I heard that putting the prepared rice, steamed buns, bread and other staple foods in the cold will produce resistant starch, and the calories of the food will be reduced. Eating such staple foods can help you lose weight!
How many friends have tried this “cold rice diet”?
Is this weight loss method reliable? Is there any scientific basis for it? Let’s talk about it in detail below.
01 What is Resistant Starch?
Starch is a carbohydrate formed by the polymerization of glucose molecules, one of the important forms of plant energy storage, and also our human carbohydrate nutrients. important source.
Starch is a relatively large family. According to the difficulty of digestion, it can be divided into three categories:[1]
Fast digestible starch: 20min in the small intestine It can be digested and absorbed, such as baked potatoes, ripe bananas, etc.
Slow-digestible starch: It can be digested and absorbed in the small intestine within 20~120min, such as natural corn starch.
Resistant starch: Non-digestible in the small intestine, found in seeds, grains, and certain staple foods after cooling. Such as cold rice, because the content of resistant starch increases after the rice is cooled.
Resistant starch is also a kind of dietary fiber. Although it cannot be absorbed and utilized in the small intestine, it can reach the colon after 2 hours and be fermented by the microflora in the colon, which helps to improve short chain Fatty acid levels, lowering intestinal pH, reducing the number of pathogens in the gut and increasing the number of probiotics are beneficial in preventing colon disease.
In addition, resistant starch has the benefits of lowering blood cholesterol, lowering the risk of obesity, and facilitating blood sugar control.
02 Cold meals help with weight loss because of resistant starch
Under normal circumstances, The starch structure contained in rice is amylose. In the process of cooking rice, amylose will absorb water and swell and gelatinize. At this time, the starch in rice belongs to fast-digesting starch, and amylase can decompose them freely and turn them into glucose. human use.
But if you don’t eat the cooked rice, but put it in the refrigerator, “aging and rejuvenation” will occur at low temperatures. At this time, the content of resistant starch in rice, that is not digested by the small intestine, increases, and it cannot be broken down into glucose for utilization.
Experiments have shown that after the prepared ordinary japonica rice is stored in the refrigerator for 24 hours, the content of resistant starch has increased from 4% to 14%, an increase of 10%. [2]
Since the calorie value of resistant starch is only about half of that of fast-digesting starch, the increase in the content of resistant starch will lead to the amount of calories that can be absorbed by the rice eaten. Lowering it will help you lose weight.
03 Some staple foods are useless when left to cool!
Since putting rice in the refrigerator may help you lose weight, does that mean that all staple foods have the same effect when eaten cold? Woolen cloth?
No!
Whether the content of resistant starch increases after the staple food is cooled has a great relationship with the composition of food starch. The effect was greater for foods high in amylose and less for foods high in amylopectin.
Because low temperature and long-term refrigeration will make the molecules of amylose tend to re-order, form crystalline regions, have retrogradation effect, and are resistant to amylase. But for foods with high amylopectin, such as glutinous rice, refrigeration has little effect on the digestion rate and blood sugar response, and even stronger blood sugar response. [2, 3]
Therefore, for rice, steamed bread and bread with high amylose content, the content of resistant starch will increase significantly after refrigeration; Don’t count on glutinous rice foods, such as glutinous rice balls, Yuanxiao, zongzi, etc. Even if you eat it cold, it will not help you lose weight and control blood sugar.
04 These factors also affect resistant starch
Except for the structure of starch In addition to affecting the production of resistant starch, it is also related to the following four factors:[4]
①Rice The longer the heating time is, the resistance to aging and regeneration The higher the starch content, the more promoting effect.
②Slow cooling was more beneficial to the production of resistant starch than fast cooling. Because the amyloid molecules in the fast cooling starch gel have no time to recrystallize and aggregate, it is not easy to form resistant starch. So, don’t freeze, refrigerate.
③The most suitable refrigeration temperature is 0~4℃, at this temperature the crystal grows faster, which is conducive to aging and regeneration. And, the entire process of resistant starch formation is generally completed within 24 hours.
④Food with too high water content is not conducive to aging and regeneration, usually a state with a water content above 60% is not conducive to the production of resistant starch, such as gruel.
Some people may have this question: what if it is cooled and then heated? Will there still be resistant starch?
Unfortunately, if the cold rice is reheated and eaten, the resistant starch content will be reduced, and it will be much lower. In the end, the resistant starch content is not even as good as when the rice is just out of the pot. Eat this Reheated rice, naturally let alone the weight loss effect.
Summary:
Although in principle, eating cold rice is helpful for weight loss, but after all, weight loss depends on the overall caloric intake level. Even if you eat cold rice every day, the total calorie intake is still high. If not, it is still difficult to lose weight. Therefore, eating cold rice will not play a decisive role in losing weight.
Furthermore, long-term insistence on eating cold rice and cold steamed bread may cause gastrointestinal discomfort. This weight loss method needs to be chosen carefully.If you have the perseverance to eat cold rice, it is better to eat a reasonable diet and strengthen exercise. The weight loss effect will be better!
Author | Xue Qingxin, member of the Chinese Nutrition Society Registered Dietitian Health Manager Public Dietitian
Reviewer | Song Shuang Associate Researcher, Institute of Nutrition and Health, Chinese Center for Disease Control and Prevention
References:
[ 1] Zhu Ping, Kong Xiangli, Bao Jinsong, etc. Research progress on the application and efficacy of resistant starch in food [J]. Journal of Nuclear Agriculture, 2015, 29(2): 327-336. DOI: 10.11869/j.issn.100 -8551.2015.02.0327.
[2] Wang Lu, Fan Zhihong, Shi Haiyan, etc. Starch digestion characteristics of several waxy foods[J]. Food Science, 2010,31(17):359-363 .
[3]Wang Shuying,Fan Zhihong,Zeng Yue,Liu Fang,Liu Bo. Effects of different rice on postprandial blood sugar and satiety response[J].Journal of Nutrition,2013,35(03): 236-240.DOI:10.13325/j.cnki.acta.nutr.sin.2013.03.014.
[4] Yu Shifeng, Zheng Xiqun. Study on the influencing factors and formation mechanism of rice RS3 resistant starch Progress[J].Food Industry Science and Technology, 2012,33(8):431-435.