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Carb-Reducing Performance of Low-Carb Rice Cookers Doubtful Control the Serving Size Rather than Count on Low-Carb Rice

  • 2021.06.15

As consumers are increasingly conscious about the benefits of a healthy diet, low-carb rice cookers have become a popular household appliance in recent years due to their claims of cooking rice with a lower carbohydrate content than that of traditional rice cookers, thus helping consumers to control their blood sugar level and body weight. However, the Consumer Council tested 11 low-carb rice cooker models and found that the average carbohydrate content per 100g of rice for low-carb rice cooked by the low-carb rice cookers was only approximately 4% lower than the normal rice cooked by the traditional rice cookers. For 1 sample, the rice cooked with the “low-carb rice mode” even contained a higher carbohydrate content than that cooked with its “normal rice mode”, casting much doubt on its carb-reducing performance. Besides, 9 samples having both "normal rice mode" and "low-carb rice mode" showed an average difference of merely 12% between the overall carbohydrate content of rice cooked by two cooking modes. The Council stressed that carb-reducing performance varied considerably among test models, while some of the samples did not even have noticeable effects. In view of this, the Council recommends consumers, in particular diabetics, not to solely rely on such product to control their condition. Instead of consuming low-carb rice, it is more direct and effective to control intake quantity for each meal.

The test covered 11 low-carb rice cooker models including 4 induction heating low-carb rice cookers and 7 fuzzy logic low-carb rice cookers, with prices ranging from $738 to $2,388. 2 models only had a “low-carb rice mode” while the remaining 9 had both the “low-carb rice mode” and “normal rice mode”. The models were tested for the carbohydrate content of the rice cooked with the normal and low-carb modes respectively, in order to assess their carb-reducing performance. In addition, the performance test items included the heat efficiency, power consumption, cooking performance, as well as the general ease of use.

When cooking rice with a traditional rice cooker, rice and water are placed in the same inner cooking pot, and most of the water would be fully absorbed by the rice. On the other hand, low-carb rice cookers have two inner cooking pots. Manufacturers claim that during the process of steam cooking low-carb rice, the rice would be rinsed many times, thus some water containing carbohydrates will be drained through the small holes in the low-carb rice basket to achieve a carb-reducing effect. In view of the disparity in the manufacturers' carb-reduction claims due to the difference in standards and units of measurement. Consumers are advised not to directly compare the information provided by the manufacturers. 

Carb-Reducing Performance 

Since rice is rich in carbohydrates and a main source of energy, the Council tested the carbohydrate content in rice to evaluate the models’ carb-reducing performance. The assessment included 2 parts:

Low-carb rice mode vs. normal rice mode:

Conducted on the 9 models having both “normal rice mode” and “low-carb rice mode”. The difference on carbohydrate content in rice cooked by the 2 cooking modes will be compared.

Low-carb rice cookers vs. traditional rice cookers:

Comparing the normal rice and low-carb rice cooked by 11 models of low-carb rice cookers against the rice cooked with a traditional rice cooker to investigate the difference in carbohydrate content.

“Low-carb Rice Mode” Versus “Normal Rice Mode”
4 Models Found with Low Carb-reducing Performance

Amongst the test models, 9 were equipped with both “normal rice mode” and “low-carb rice mode”. The test revealed that per 100g of rice, the average carbohydrate content of rice cooked with the “normal rice mode” was 36.6g, while that of low-carb rice cooked with the “low-carb rice mode” was 32.2g, representing a reduction of 12%. Only 5 models of low-carb rice showed a significant drop in carbohydrate content ranging from 10.1% to 45.3%. 3 models showed less than 10% reduction in carbohydrates, whereas 1 model was as low as 0.6%, which was a marginal difference compared with normal rice. Besides, the carbohydrate content of 1 sample of low-carb rice was even higher than that of its normal rice by 1.7%.

In fact, if the amount of raw rice remains unchanged, the difference in carbohydrate intake when consuming low-carb rice and “normal rice mode” rice was insignificant. Taking the model with the highest reduction in carbohydrate level as an example, per 100g of rice, the carbohydrate content of rice cooked with the “low-carb rice mode” was 45.3% lower than that cooked with the “normal rice mode”, while the moisture of rice increased by 31.6%. Therefore, if the serving size remains unchanged, consuming the low-carb rice would have a higher water moisture intake and smaller carbohydrate intake. Upon comparing the same model, however, if 75g of raw rice (around the serving size of 1 bowl of rice cooked by regular rice cookers) is cooked with two cooking modes respectively and consumed in one sitting, the total carbohydrate content of the rice cooked with the “low-carb rice mode” was merely 0.6% less than that cooked with the “normal rice mode”, representing an insignificant difference. Besides, as the moisture content of low-carb rice was 139% higher than normal rice, consumers should pay heed to control the serving size in order to achieve a carb-reducing effect.

6 Models Counterproductive in Carbohydrate Reduction When Compared with Traditional Rice Cookers

The test also measured the carbohydrate content of normal rice cooked by a traditional rice cooker without a low-carb rice mode and compared it with the low-carb rice cooked by the 11 models. Per 100g of rice, the carbohydrate content of the low-carb rice cooked by 6 models were found to be even higher than the normal rice cooked with traditional rice cookers, while only 2 models had a relatively lower carbohydrate content. Despite the fact that the carbohydrate content of rice might be affected by various factors, such as the differences in the model’s cooking mode, water consumption and temperature. But the test results indicated that low-carb rice is not necessarily healthier than normal rice. If consumers let their guard down and increase the serving size of low-carb rice, it may counterproductively increase the carbohydrate intake and pose health risks.

Normal Rice Cooked by Low-carb Rice Cookers Contained Relatively High Carbohydrate Content

The test also found that for the 9 models having both “normal rice mode” and “low-carb rice mode”, the average carbohydrate content in rice cooked with the “normal rice mode” was 36.6g per 100g of rice, which was 12% higher than normal rice, which contained 32.7g carbohydrate, cooked by a traditional rice cooker. Consumers should be mindful that long-term consumption of rice cooked with the “normal rice mode” of low-carb rice cookers will increase the intake of carbohydrate.


As the temperature of rice will impact its taste and texture, the rice cookers’ warm-keeping performance is therefore equally important. The test results revealed that 9 models had satisfactory warm-keeping performance and were able to maintain the temperature at between 65ºC to 80ºC, which complies with the standard requirements. However, 1 model of low-carb rice cooker had an average warm-keeping temperature of over 80ºC which may dry up the rice, while another model had an overly low temperature of under 60ºC and may promote bacteria growth.

In terms of the power consumption, the 9 models with both the “normal rice mode” and “low-carb rice mode” generally had a higher power consumption since it uses more water when cooking low-carb rice.

Based on the recommendations from the Department of Health, Hong Kong Medical Association and Hong Kong Dietitians Association, consumers should think twice before purchasing low-carb rice cookers:

- The Department of Health opines that low-carb rice cookers use more water when cooking low-carb rice. As a result, some nutrients such as carbohydrates and water-soluble vitamin B may dissolve in water and be lost when the residue water is poured away, thus lowering the nutrient content of low-carb rice and potentially hindering the growth of children and teenagers or lead to weight gain;
- The stability of low-carb rice is yet to be tested and confirmed. Therefore, it is not recommended for diabetics to rely on low-carb rice cookers to control their condition;
- The Hong Kong Medical Association also reminds that low-carb rice cookers achieve carb-reducing effect by using large amount of water in order to dissolve the starch in rice into water. However, some tests have revealed only a small portion of starch (1 to 3%) is dissolved in water. Therefore, the impact on the glycemic index (GI) is low;
- The Hong Kong Dietitians Association recommended that in order to stay healthy while eating rice, the simplest and most direct way is to control the serving size of rice. To increase satiety, ingredients such as oats, mushrooms, carrots, corn and beans could be added when cooking rice.

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