Why We Eat (Too Much): The New Science of Appetite

by Andrew Jenkinson

Why would over-nutrition, or obesity, during pregnancy lead to the development of traits that predispose the offspring to gain further weight? This seems to be counter-intuitive. We can understand why obesity traits are found in the genes of those babies who are predicted to grow in a harsh environment, but what is the advantage in terms of survival of having these traits if the food environment is predicted to be plentiful? The answer may come from the lack of micronutrients in the Western diet. Despite a mother being over-weight, she may have vitamin, mineral or other deficiencies because the processed food she is consuming doesn’t contain the same nutrition as old-fashioned fresh foods (we discuss this further in chapter 8). The genes in the foetus sense the deficiencies in the mother and the genetic expression of those genes is thus altered to ensure that enough foods are consumed in the future environment to avoid a similar deficiency. Scientists at Duke University have confirmed that administration of vitamin supplements to mice during pregnancy can profoundly alter the way the offspring look.27