Is it because my sister becomes fat? Research evidence: Sisters are 30% more likely to be obese than sisters

 8:42am, 7 September 2025

Weight loss is the question that many women care about the most, but before losing weight, first check if they have a younger sister, because a recent Swedish study pointed out that among sisters, the chance of sisters being too heavy is as high as 29%, and the BMI index of sisters is 2.4% higher than that of sisters. Is it hard to have a younger sister, but will the older sister become fat?

Many girls like to have a sister or sister because the relationship between sisters will be particularly good, but this may also affect each other's weight.

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Sweden studied more than 10,000 pairs of sisters, and found that after both parties became adults, the sister's overweight probability was 29%, and the sister's BMI value was 2.4% higher than that of her sister, which represents that on average, sisters were fatter than her sister. Another study in Oklan in the United States also pointed out that the first child in the family is prone to obesity because of the poor insulin function in the body.

Why is the sister fatter than the sister? This is because when the mother is pregnant for the first time, the blood vessel walls that provide fetal nutrition are thinner, so the nutritional score is more in the baby's body. Usually, the mother will take care of her first child, eat more food, and pay more attention to nutrition and health. In addition, after birth, care is more thorough and care about eating. If you are cautious, you may make the first child grow better.

But in fact, this is just a data conclusion on the survey, which does not mean that the sister must be fatter than the sister. If you want to lose weight, you still have to rely on exercise and diet to achieve the purpose of controlling weight. Naturally, the sister may be thinner than the sister.