Obesity is a highly complex phenomenon that is not fully understood. The traditional viewpoint, and one that is still enshrined in the mainstream today, is that weight gain is a simple case of eating too much food and performing too little exercise. However, increasingly animal and human studies show that this oversimplified theory of weight gain is not only incorrect, but its widespread belief by the medical expert and layperson alike, is preventing the development of effective fat loss strategies. Evidence from the nutritional literature suggests that it is not how much you eat that is the determining factor in weight gain, but rather, what you eat. In particular, consumption of the typical Western diet, with its high processed food content, containing multiple metabolic poisons, may be a primary driver of insulin resistance which is in thurn the primary driver of weight gain. However, while the Western diet may be a causative factor in weight gain, its consumption clearly does not have the same metabolic effects in everyone.
That some groups of individuals gain weight at different rates compared to other groups of individuals is interesting and has been investigated by nutritional researchers. In this regard sex and race interactions have been observed. In one study1, the relative body weights of 1830 children from low income families were measured from the ages of 2 to 18 years. These body weight measurements were then used to calculate a weight for height index, similar to the body mass indices commonly in use, but instead related to the mean weight for height. The results showed that the black male children had the lowest prevalence of obesity, when compared to white males and black or white females. Grouping overweight and obese criteria together, it was found that white females contained the lowest prevalence of overweight-obese children, followed by black males, white males and then black females. Most of the variance in weight for height variance from the mean could be explained by the black female children.
These results suggest that both sex and race factors influence the prevalence of obesity. This suggests that genetic factors are related to the risk of obesity. While this study investigated the effects in children of low socioeconomic status, there is no reason to assume that similar effects might be present in those from higher socioeconomic groups, although the total prevalence of obesity may be lower in the latter. That genetic factors are important in the development of obesity is not surprising as people all have different biochemical profiles that modify the environmental factors that individuals are exposed to. The observation that most of the black females failed to fall within the normal range for body weight, suggests that this group of individuals is particularly exposed genetically to the environmental factors that contribute to, and drive, obesity. These results certainly add more weight to the argument that overeating per se is not the cause of obesity, but that other more complex factors are at play.
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