Overweight and mortality in Mexican Americans

The Geriatric Research Centre (GRC) table of desirable weights is based on the mortality experience of holders of 4.2 million polices issued by 25 life insurance companies in the USA and Canada. The GRC table defines optimum weight-for-height as the weight range which is associated with below average mortality for a given age and height group. People who fall outside this range, i.e. overweight or underweight, experience above average mortality for their age and height group. We classified 3176 Mexican Americans and 1841 non-Hispanic whites who participated in the San Antonio Heart Study according to the GRC table and found that Mexican Americans were less likely than non-Hispanic whites to be underweight and more likely to be overweight. The two effects did not offset one another, however, and fewer Mexican Americans were found to be in the 'just right' range. If the mortality experience of the populatio which generated the GRC table (largely non-Hispanic) applied to Mexican Americans, these results imply that Mexican Americans should have higher mortality rates than non-Hispanic whites. Vital statistics data from the state of Texas for the years 1979-81, however, fail to corroborate this prediction. Beyond age 45 years, an age range in which obesity and obesity-related disorders would be expected to exert an important influence on mortality, age-specific and age-adjusted all cause mortality was at last as good if not better in Mexican Americans than in non-Hispanic whites. These results could not be explained by ethnic differences in body fat distribution, since fat was less favorably distributed in Mexican Americans. The results strongly imply that tables of ideal weights derived from non-Hispanic populations are not applicable to Mexican Americans who appear to tolerate higher body weights without an adverse impact on their mortality experience. There is a need for prospective data from Hispanic and other minority populations to derive tables of ideal weights specific to these populations. In the meantime it should be realized that conventional tables, derived from non-Hispanic populations, most probably underestimate the ideal weight range for Mexican Americans.