Due to the increasing prevalence of obesity, interest in nutrition has increased. Every 5 years, the US Department of Agriculture (USDA) revises the nutrition guidelines; the last publication was in 2015. The “pyramid” from 2005 has been changed to a graphic similar to the “My Plate” diagram recommended for weight control (http://www.chosemyplate.gov) and not only reflects the known requirements and “conventional” scientific wisdom for nutrients, but also, to some extent, represents a realistic and simplified recommendation based on what the American public is willing to accept and follow (Figure 16-1). The ChooseMyPlate website also contains recommendations for pregnancy. The nutrition guidelines may unfortunately reflect pressure from the food industry, according to many nutrition advocates.
The USDA ChooseMyPlate representation. (From the USDA’s Center for Nutrition Policy and Promotion, myplate.gov.)
The overall body of evidence examined by the 2015 Dietary Guidelines Advisory Committee (DGAC) identified that a healthy dietary pattern is higher in vegetables, fruits, whole grains, low- or nonfat dairy, seafood, legumes, and nuts; moderate in alcohol (among nonpregnant adults); lower in red and processed meats; and low in sugar-sweetened foods and drinks and refined grains.1
The practicing obstetrician/gynecologist has the responsibility to be well versed in nutrition. We are sometimes the only physicians women see on a regular basis. Also, women usually make the food decisions for the family, so educating them may result in benefits to men and children. It appears that once obese, an individual has a difficult time achieving a normal weight. Therefore, prevention of obesity is a crucial goal.
Another reason that we are important in battling this disease is that obesity affects every aspect of obstetrical/gynecological practice. The increase in morbidity and mortality in pregnancy,2 infertility issues, gynecologic cancers (with poorer survival3), and complications of surgery in the obese woman impels us to contribute to the prevention and treatment of obesity. The cornerstones of prevention and treatment are proper nutrition, exercise, and education of both the patient and physician.
BASIC PRINCIPLES OF NUTRITION
Energy Concepts and Metabolism
As machines, we are obligated to obey the laws of thermodynamics. The first law of thermodynamics states that the total amount of energy in the universe remains constant; therefore, our bodies cannot independently produce energy but must obtain it by ingesting nutrients and converting the energy obtained into other forms. The second law of thermodynamics states that any energy transformation is always in the direction of increased entropy, or disorder, and cannot be recovered for later use. The goal of our metabolism is to preserve a steady state. In our bodies, we actually do not obtain equilibrium, the complete reversibility of all reactions, but a “near” ...