In Southern California, generations of immigrants are creating an evolving definition of "American." Multi-American is your source for news, conversation and insight on this emerging regional and national identity.

The conventional wisdom is that almost all Asian-Americans are thin. In her stand-up routine, Asian-American comic Amy Anderson says women are constantly asking her how she stayed so slim post-pregnancy.

"My secret? I don't know," Anderson says. "I’m Asian? That's my secret."

A new report from the federal Centers for Disease Control and Prevention appears to back up the wow-Asian-Americans-really-are-skinnier idea. The National Health and Nutrition Examination Survey found that 11 percent of Asian-Americans are obese - compared to a national average of 35 percent.

But some public health experts say those statistics are at best misleading, and at worst, harmful, because obesity-related disorders such as diabetes, hypertension and joint disease can strike Asian-Americans at lower weight levels than other Americans. Now a group of physicians is asking the medical community to redefine what it means to be obese for Asian-Americans.

Fat, hidden from view

Dr. George King of the Harvard-affiliated Joslin Diabetes Center said it's not known for sure why, but Asians tend to have more abdominal fat surrounding internal organs, such as the liver and kidneys.

"It tends to make Asians look not overweight," King said. "But the fat content is actually higher."

The medical community uses height and weight ratios to determine where patients fall on the Body Mass Index. A BMI of 30 means a patient is considered obese and at high risk for heart and renal problems.

But medical experts say Asian-American patients can start showing obesity-linked problems at BMI's as low as 24.

King said that "we know that diabetes, at least in Asian countries and in some smaller studies in the US, is actually occurring at a much higher rate than in the Caucasian population."

Lowering the BMI cut-off

King and other prominent physicians - many of them members of the National Council of Asian Pacific Islander Physicians - are calling on the medical community and the insurance industry to adjust BMI cutoffs for Asian-Americans.

Otherwise, Asian-Americans may not receive obesity prevention treatment, said Dr. Edward Chow, executive director of the Chinese Community Health Care Association in San Francisco.

"We're really going to miss that opportunity to look at the early overweightedness of a part of our population," Chow said.

Chow said he's also worried that some Asian-Americans are not getting insurance reimbursement from private and public payors because their weight-related disorders are not captured by the BMI of 30 threshold.

"This is where we're trying to get the federal government to recognize the lower level related to the ethnicity of the patient, rather than simply a number that has come up because it happens to be the Caucasian standard," Chow said.

New standards can't be one-size-fits-all

Asked about efforts to adjust BMI standards for Asian-Americans, a spokeswoman for the National Heart, Lung, and Blood Institute wrote that the agency is working on future guidelines with professional societies.

The American Diabetes Association is also looking at the issue. Senior vice president Dr. Jane Chiang said the group is currently evaluating "evidence-based" medical literature and plans to come out with recommendations on BMI cutoffs for Asian-Americans and Pacific Islanders by early 2014.

Chiang said that because the community is so heterogenous, recommendations will vary according to the different ethnic groups. The BMI cutoff for Samoans may not work for Vietnamese-Americans, for example.

"People think an Asian is an Asian, but it's not true," Chiang said.

Pending the revision of BMI guidelines for Asian Americans, Chiang recommended that physicians look beyond someone's weight and consider whether a patient has a family history of particular illnesses such as diabetes.