As discussed here and here, epigenetics is rapidly emerging as a prominent focus of study in the natural and life sciences, but has not quite yet made much of an impact on public awareness. (For those unfamiliar with epigenetics, the name comes from the Greek root epi-, meaning ‘above’ or ‘over,’ which when combined with genetics denotes the study of genetic processes ‘above’ the genome.) Epigenetics is gradually making inroads into public consciousness in a number of different ways, and this blog is my contribution to this effort. However, there is a problematic trend in the popularization of epigenetics that needs to be pointed out and corrected when possible: the overbroad definition epigenetics. The danger from this trend is that it damages the legitimacy of epigenetics, dilutes the potential impact of epigenetics, and obscures the true magnitude of the implications of epigenetics for mapping the genome for diagnostic and predictive purposes and drug discovery, as well as for policy.
I have observed this problem in a number of different places before, but what prompted me to write this post was a recent article on the health and fitness site BreakingMuscle.com titled “Getting Personal: Working Out the Way Your DNA Intended” in which the guest author refers to the use of epigenetics in the creation of personalized fitness programs. To many this might seem like a trivial case that doesn’t merit much attention, but it actually demonstrates a serious problem regarding the popularization of epigenetics. Research in epigenetics has produced a number of novel insights into how our genes work and how our genes interact with our environments, many of which have direct application to health and fitness, so I was intrigued to see how the author applied epigenetics in this domain. Instead, what I found was a good demonstration of this common misunderstanding about and misuse of epigenetics.
“Getting Personal” with Epigenetics
In this article, the author recounts his interactions with a new training client who was having difficulty reaching her fitness goals following conventional exercise regimes. Her knees were also swelling and in pain, and she was getting injured. “At this juncture,” the author writes, “she was both mentally and physically exhausted. And none of her considerable efforts were showing any sign of making a difference in her body.”
In his consultation, the author promises her that by understanding her epigenetics they will create an individualized fitness plan that is truly effective. He explains to her that “epigenetics [is] a way to understand the effect of her lifestyle and environment on the way her genes were expressed in her body,” and that “the key would be to develop a personalized program and training regimen that took into account her body structure and epigenetic demands.”
The author does this first by measuring her different body parts, which are a function of her “genetic makeup.” This information (called “anthropometry”) is then used to find the best exercise regimes for her individual body type and body mechanics. Next the author writes about the role of hormones in exercise and fitness, observing that because “your shape is a function of your hormones…if you change your hormonal levels, then the shape of your body may also change.” The author then writes how activation of muscles stimulates organs and supports hormonal balance which strengthens metabolic functions and improves performance and well-being, but that doing the wrong kinds of exercises for a body type can result in inflammation, injury and fatigue.
The rest of the article details how the author applies these anthropometrics and other personal information about his client to construct a personalized exercise and diet plan for her, and of the success of this approach. The author concludes with the observation that “for Alice, an individualized fitness plan based on gene expression and epigenetics made working out rewarding both internally and externally and revealed a path to optimal well-being,” and the recommendation that “for other coaches, I encourage you too to discover the power of these scientific insights to help your clients reach their goals. And for athletes, ask your coach about epigenetics or anthropometry or seek out a coach who specializes in this approach.”
What is Epigenetics, and Why Should You Care When it Comes to Health and Fitness?
I do not dispute the merit of personalization for designing effective exercise programs, and I concede to the authors considerable expertise in regards to training clients. However, I do take issue with the author’s use of ‘epigenetics’ to describe this approach to training and fitness, which I think fatally misconstrues epigenetics and obscures much of what is truly exciting about epigenetics.
Other than a basic definition, the author does not provide much explanation of his references to epigenetics in the body of the article. However, in the comments to his article the author does distinguish between a medical or scientific definition of epigenetics which refers to specific processes which act on the genes “from the outside,” versus a health industry context which defines epigenetics “in a general sense [as] our environment or lifestyle,” which includes anything with “the potential to effect the expression of our genes, and our ultimate health” from climate to stress levels to diet and exercise, and that he is utilizing the latter.
While in a very broad sense ‘epigenetics’ by definition includes anything which affects gene expression from outside the genome, this definition is much too ambiguous to draw any useful distinctions because basically everything that isn’t specifically from the genes is therefore epigenetic (e.g., under this definition, gravity is an epigenetic factor). The author states that he intentionally uses this amorphous definition as a means to illustrate “some basic concepts to consider regarding personalized training and epigenetics [to] those fairly new to the field.” While I appreciate the intention to inform and educate those who are not yet aware of epigenetics, nothing of value is gained by extending the scope of epigenetics to include practically everything that is not specifically genetic in origin. In the end this overly ambiguous definition of epigenetics does more harm than good, and actually dilutes and obscures the more profound implications of the science of epigenetics for health and fitness and longevity.
For these reasons limiting the definition of epigenetics to those biological processes which influence or regulate gene expression is the most appropriate and useful definition, even for those new to epigenetics (see this video from the University of Utah Genetic Science Learning Center for a good visual introduction about epigenetics defined in this way). This definition of epigenetics is at once specific enough to make meaningful exclusions but yet still comprehensive enough to include most of the environmental factors mentioned by the author in the original article, especially because the biological pathways of most of these factors have already been the focus of research in epigenetics. A significant caveat, though, is that limiting epigenetics to these biological processes may disqualify many of the facile uses often called ‘epigenetic;’ still, the gains in rigor from this limitation more than offset any such ‘losses’ in description.
For example, ‘epigenetics’ as used by the author of the article that prompted this post meant “the climate we trained in (outdoor v indoor airconditioned), time of training session (based on hormone production and fluctuations), fuel/food consumed pre-, during, and post- workout (according to desired biochemical outcomes), type/intensity/frequency of exercise (according to neuro-predictors of mood/stamina/engagement), solo versus group training (determined by personality type, time of cycle, etc), and many more which all effect the way our genes express;” however, how the recommendations for diet and exercise from these factors influenced genetic expression was never addressed. In the words of a commenter to this original article, instead of a true epigenetics-based treatment this method is just “personalized training based on individual phenotypic variation,” to which the author basically agreed.
In contrast, this more rigorous definition of epigenetics allows for some truly epic health- and fitness-related discussions that extend far beyond the design of a personalized training regimen. One such epigenetic process for which evidence has been found is that the physical condition of parents at the time of conception—in particular whether they are obese or not obese—actually contributes significantly to the obesity of their children through specific biological pathways. Further, additional research on both humans and animals also suggests these epigenetic effects can be passed on for up to four generations. In other words, one of the real implications of epigenetics for health and fitness is that maintaining proper physical fitness may not only be important for one’s own well-being, but may also have significant health benefits (or costs) for one’s children, grandchildren and possibly great grandchildren; and this is only one example of the repercussions epigenetics.
Consider the political and philosophical implications of this evidence that the choices as to diet and exercise of an individual in one generation can extend two, three or even four generations down the line: Obesity is already recognized as a multi-billion dollar factor in rising health care costs in both developed and developing countries, and as such is becoming an increasing focus of government policy, but these policies are being discussed only in the non-epigenetic context of the effects of obesity on current individuals and society—how much more pressing does addressing obesity become if the health and well-being of future individuals and societies two or three generations distant are directly implicated? Likewise, how does this impact of present choices on future generations interact with the importance placed on individualism in political cultures like that of the United States? What is the appropriate balance between protecting the liberties of currently living individuals and safeguarding the conditions of future individuals and societies? These kinds of questions about the political implications of epigenetics are explored further in this post about epigenetics and autism and in this series of posts.
These are just some examples of the scope of the issues and the incredibly profound questions which are posed by this more rigorous definition of epigenetics, and is just one illustration of why definitions are important.
Can you think of any other examples in which a less rigorous definition of epigenetics is possibly distracting from the true magnitude of the implications of epigenetics? Or am I blowing this out of proportion?
I am curious to hear what you think. Leave your comments below and I will respond.
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 Martínez, J. A., Cordero, P., Campión, J., & Milagro, F. I. (2012). Interplay of early-life nutritional programming on obesity, inflammation and epigenetic outcomes. Proceedings of the Nutrition Society, 71(02), 276-283; Soubry, A., Schildkraut, J. M., Murtha, A., Wang, F., Huang, Z., Bernal, A., … & Hoyo, C. (2013). Paternal obesity is associated with IGF2 hypomethylation in newborns: results from a Newborn Epigenetics Study (NEST) cohort. BMC medicine, 11(1), 29; Wu, Q., & Suzuki, M. (2006). Parental obesity and overweight affect the body‐fat accumulation in the offspring: the possible effect of a high‐fat diet through epigenetic inheritance. Obesity reviews, 7(2), 201-208.
 Guerrero-Bosagna, C., & Skinner, M. K. (2012). Environmentally induced epigenetic transgenerational inheritance of phenotype and disease. Molecular and cellular endocrinology, 354(1), 3-8; Heijmans, B. T., Tobi, E. W., Stein, A. D., Putter, H., Blauw, G. J., Susser, E. S., … & Lumey, L. H. (2008). Persistent epigenetic differences associated with prenatal exposure to famine in humans. Proceedings of the National Academy of Sciences, 105(44), 17046-17049; Manikkam, M., Haque, M. M., Guerrero-Bosagna, C., Nilsson, E. E., & Skinner, M. K. (2014). Pesticide Methoxychlor Promotes the Epigenetic Transgenerational Inheritance of Adult-Onset Disease through the Female Germline. PloS one, 9(7), e102091; Manikkam, M., Tracey, R., Guerrero-Bosagna, C., & Skinner, M. K. (2013). Plastics derived endocrine disruptors (BPA, DEHP and DBP) induce epigenetic transgenerational inheritance of obesity, reproductive disease and sperm epimutations. PLoS One, 8(1), e55387; Tobi, E. W., Lumey, L. H., Talens, R. P., Kremer, D., Putter, H., Stein, A. D., … & Heijmans, B. T. (2009). DNA methylation differences after exposure to prenatal famine are common and timing-and sex-specific. Human molecular genetics, 18(21), 4046-4053.