2. Soymilk is not high in calories. We usually consume only 42 calories when drinking a cup of 300ml soybean milk, but we should know that a cup of 300ml milk contains 150 calories, while a cup of 300ml coke contains 130 calories. Through this comparison, we can see that the calories of soybean milk are really low. But when drinking soybean milk, many people think it is not delicious, so they will put some sugar in it. In this case, the heat of soybean milk will increase. A cup of 250g sweet soybean milk contains about 83 calories.