Black American men are the least likely male ethnic group to be overweight or obese in America (69.2 percent) compared to ‘Hispanic’ men (78.6 percent) and white men (71.4 percent) (Ogden et al, 2014). As a result of being less likely to be obese, black men as a whole suffer from diabetes and other diseases that are correlated with higher body fat. Conversely, for women the rate for white women is 63.2 percent, 77.2 percent for ‘Hispanic’ women and 82.4 percent for black women. Why do black men have lower rates of obesity and chronic health diseases?
Klimentidis et al (2016) set out to find why black men have lower rates of obesity than black women despite having the same socioeconomic and environmental factors. Using 2814 self-identified African Americans from the Atherosclerosis Risk in Communities study, they estimated each individual’s degree of African ancestry using 3,314 genetic markers. They then tested whether sex modifies the association of West African genetic ancestry and body mass index, waist circumference, and waist to hip ratio. Also, they adjusted for income and education as well as examined associations of ancestry with the phenotypes of males and females separately. They recreated their results with the Multi-Ethnic Study of Atherosclerosis (n= 1611 AA).
They discovered that West African ancestry is negatively correlated with obesity as well as central obesity, which is obesity around the midsection, among black men but not black women. Also noted, was that black men with more African ancestry had a lower waist to hip ratio and less central adiposity than black men with less African ancestry. They conclude that their results suggest that a combination of male gender and West African ancestry is correlated with protection against central obesity and suggests that a portion of the difference in obesity (13.2 percent difference) may be due, in part to genetic factors. The study also suggests that there are specific genetic and physiologic differences in African and European Americans.
This study confirms two things. 1) Black women are more likely to be obese than black men as well as the general population. 2) Black men have less of a chance of becoming obese or overweight as well as less of a chance of incurring the risks that come along with being obese or overweight. The degree of African ancestry is the cause in both black men and black women for these differences in the rate of overweight and obese individuals in both populations. One of my theories also got confirmed. Since obesity is partly genetic in African Americans, and black girls have an earlier menarche (period) than white girls due to higher body fat which activates the hormone leptin, which precedes an increase in body fat to prepare for eventual menstruation, I theorize that black girls have earlier menarche than white girls due to r/K Selection Theory. It’s an evolutionary advantage to be able to have children earlier, as the population dies younger.
Evolutionarily speaking, black men needed to be more fit in order to protect the clan from predators. This is also why blacks evolved narrower hips (Rushton, 1995). Higher body fat allows for more protection for a baby in vitro, which is why an increase in leptin precedes an increase in body fat, which then causes black girls to have an earlier puberty.
One of the questions I would like answered is whether it’s the actual degree of African ancestry that is the cause of black men being less likely to be obese or it’s the cause of higher degree of European ancestry. European American men do have a slightly higher risk of being overweight or obese than African American men, so there is some credence to this hypothesis. Three SNPs were found to be correlated with obesity in African American populations as well as European American populations; this could be one cause.
Wagner and Heyward (2000) discovered biological differences exist between blacks and whites. They reviewed the literature on the differences between blacks and whites in fat-free body mass (water, mineral, and protein) fat patterning and body dimensions and proportions. Blacks, in general, have greater bone mineral density and body protein content than do whites, resulting in lower fat-free bone density. They also note racial differences in the differences of subcutaneous body fat, which is the body fat that’s just below the skin, as opposed to visceral body fat which is found in the peritoneal cavity, which can be measured with calipers to give a rough estimate of total body fat adiposity. The conclusion reached in the study was that differences in FFB (fat-free body) was statistically significant between blacks and whites. They also have a greater BMC (bone mineral content) and BMD (bone mineral density) than do whites. They also argue that for a given BMI (body mass index), blacks might have less adiposity because they tend to be more mesomorphic. Researchers push for the development of racial-specific equations to better see differences in FFB.
With the above study noting that there is a substantial difference between blacks and whites in FFB, there may be some truth to a negative effect of European ancestry on blacks in terms of obesity acquisition. However, lower FFB in black men is one reason why black men can’t swim as well as whites.
One of the causes for both racial and gender discrepancies in obesity is genetic in origin. The difference between black men and black women is 13.2 percent whereas for white men and white women the difference is 8.2 percent. There is a clear genetic difference between races that is the cause for this discrepancy. Black men and black women have the same socioeconomics status and live in the same environment, so some of the differences in obesity noticed in this population must be genetic in origin.
Freedman et al (2004) observed that, as expected, black men were more likely to choose heavier figures as an ideal body for women than white men. Also expected was that both groups would choose figures with a low waist to hip ratio, but black men would choose a lower waist to hip ratio as ideal. They also show weight to be a more important cue than waist to hip ratio in mate selection as well as supporting the theory that black men’s preferences may serve as a protective factor against eating and body image pathology in black women.
To give an example of the above study in action, we can look at Mauritania. They force feed their women up to 16,000 kcal a day in an effort to make them obese, as that’s what is seen as attractive in their society. Mauritanian love songs also describe the ideal woman as fat. Obesity is so celebrated in their society that parents beam at the fact that their daughters look obese, as they have a better chance of getting partners.
The higher the degree of West African ancestry in black men, the lower the chance they have for obesity. I do wonder, though, if it’s because they have less European ancestry or because they have more African ancestry. Black men with more African ancestry are less likely to be obese than black men with less African ancestry, so there is a correlation there that I would like to see explored in the future. Differences in fat-free body mass have been noticed between blacks and whites, but this is one of the first studies to my knowledge that shows that genetic differences between black men and black women may be part of the cause for obesity differences in that population. Cultural differences in perception of beauty, of course, come into play in regards to differences between black and white men, however, the cause of black women having higher rates of obesity is due in part to genetic factors, which then leads to black men liking that as their beauty standard.