While a recent report from the Centers for Disease Control and Prevention (CDC)suggested that almost 40% of American adults are currently obese, the new research predicts that over 57% of today’s children will be obese by the time they reach the age of 35.

Obesity is classified as having a body mass index (BMI) of 30 or higher. BMI is calculated by dividing the subject’s weight in kilograms by the square of their height in meters.

BMI is the most widely used system for establishing whether someone is underweight, of normal weight, overweight or obese. However, it’s rather simplistic and is controversial as a health indicator, as it doesn’t take into account the differences between fat and muscle (which is heavier than fat), nor does it factor in ethnic background.

The new research took data from five earlier studies about actual American children and adults’ height and weight, and simulated growth trajectories in order to project where today’s kids were likely to end up by the age of 35.

The results showed that 57.3% of today’s kids, up to the age of 19, will be obese by the age of 35. Of those, around half will become (or already be) obese during childhood, and half will become obese later on.

For those children who are already severely obese—that is, with a BMI of 35 or more—the chances that they will cease to be obese by their 35th birthday drop with age. At the age of two, the likelihood of that happening is 21%; by 19, the likelihood drops to 6.1%.

The age of 35 was picked for the study because that’s when obesity-related conditions such as diabetes and heart disease often start to kick in.

“On the basis of our simulation models, childhood obesity and overweight will continue to be a major health problem in the United States,” the researchers wrote. “Early development of obesity predicted obesity in adulthood, especially for children who were severely obese.”

美国疾病控制与预防中心（CDC）最近发布一份报告称，现在将近四成美国成年人属于肥胖一族。而哈佛大学的研究预计，57%的美国儿童到35岁都会变成肥胖者。

测算肥胖的指标是身体质量指数（BMI），达到30或以上就属于肥胖。BMI的算法是体重（公斤）除以身高（米）平方得到的结果。

BMI是衡量一个人体重偏低、正常、超重或肥胖最常用的标准。不过，BMI较为简单也引起一些争议。因为该指标没有考虑脂肪和肌肉的差别（同体积的肌肉比脂肪重），也没有考虑不同种族标准体重不同。

哈佛大学新研究使用的数据基于之前五项研究，具体内容是当前美国儿童和成人体重和身高数据。为了预测研究对象的体重在35岁以前如何变化，该研究会对成长趋势进行模拟。

结果显示，目前19岁以下的美国青少年里57.3%将在35以前变肥胖，其中约半数童年时期就会（或已经）肥胖，另外约半数将在成人后肥胖。

对目前BMI就超过35的严重肥胖孩子们来说，年龄越大他们在35岁以前摆脱肥胖的几率就越低。比如目前两岁的严重肥胖孩子，35岁以前改变肥胖状况的几率还有21%，而19岁严重肥胖的少年几率就降至6.1%。

哈佛研究之所以用35岁当分界线，是因为人到35岁就可能开始出现糖尿病和心脏病等肥胖导致的并发症。

“基于模拟模型，童年肥胖和超重仍将是美国一大健康问题，”研究人员写道，“小时候肥胖预示了成年后很可能也会肥胖，如果小时候就严重肥胖，可能性就更大。”（财富中文网）

译者：Pessy

审稿：夏林