Obesity and Male Reproduction; Placing the Western Diet in Context

Abstract

There is mounting evidence that obesity has negative repercussions for reproductive physiology in males. Much of this evidence has accumulated from rodent studies employing diets high in fat and sugar ("high fat" or "western" diets). While excessive fats and carbohydrates have long been considered major determinants of diet induced obesity, a growing body of research suggests that the relationships between diet composition and obesity are more complex than originally thought, involving interactions between dietary macronutrients. However, rodent dietary models have yet to evolve to capture this, instead relying heavily on elevated levels of a single macronutrient. While this approach has highlighted important effects of obesity on male reproduction, it does not allow for interpretation of the complex, interacting effects of dietary protein, carbohydrate and fat. Further, the single nutrient approach limits the ability to draw conclusions about which diets best support reproductive function. Nutritional Geometry offers an alternative approach, assessing outcomes of interest over an extended range of dietary macronutrient compositions. This review explores the practical application of Nutritional Geometry to study the effects of dietary macronutrient balance on male reproduction, including experimental considerations specific to studies of diet and reproductive physiology. Finally, this review discusses the promising use of Nutritional Geometry in the development of evidence-based pre-conception nutritional guidance for men.

Keywords: diet; high fat; male fertility; nutritional geometry; obesity; reproduction.

Figure 1

Factors impacting male fertility and models to study effects of diet. A variety of intrinsic and extrinsic factors can contribute to poor reproductive performance and infertility in men. Of the extrinsic factors, the impact of diet and obesity on male reproduction has received a significant amount of attention. The effects of diet and obesity on male reproduction are typically investigated in rodents using the classic “western diet” approach, comparing control and treatment diet outcomes. Here, we instead propose the use of Nutritional Geometry, employing a range of diets which systematically differ in their proportions of protein, carbohydrates, and fat. Image created with BioRender.com.