Moderate consumption of crab does not cause the organism to be overweight or obese, but if overconsumption may cause the organism to consume too many calories, leading to obesity. Every 100 grams of crab and 103 calories, of which 17.5 grams of protein, 2.6 grams of fat, 2.3 grams of carbohydrates, vitamin A389 micrograms, vitamin E6.09 milligrams, 1.7 milligrams of niacin, 181 milligrams of potassium, 126 milligrams of calcium, 56.7 milligrams of selenium. Therefore, crabs contain a large amount of high-quality animal protein with high absorption rate and a complete range of amino acids; at the same time, the calcium and selenium content in crabs is high, which can be used as a high-quality food source of these two elements. Moderate consumption will not cause overweight or obesity, and there is some nutritional value for the human body. However, because crabs contain some fat and cholesterol, excessive consumption can cause excessive calorie intake and overweight or obesity. Excessive consumption is not recommended for people who want to lose weight. Those who are allergic to crabs are prohibited from eating crabs.