My love-hate nemesis is back. One encounter and our paths take a long time to diverge again. Despite all my efforts, my avoidance tactics have again failed and our paths have again converged. I speak, of course, of a delicious donut and its long-term clinging to my waist line.

As we age, our metabolism slows. The battle to shed pounds and support the svelte forms of our youth only becomes more difficult. But, numerous companies have sprung up to “help” us with our Herculean efforts to behave. Do any of them offer a valid method to help me sever ties permanently with the seductive donut?

Perhaps. Some genetic tests are now commercially available that promise to tell you the ideal diet based on your genes. Perusing some of the gene-recommended diets, it is clear they have captured what has always been promoted as a healthy diet (Robbins, 2016; Miller, 2018). Alas, I am looking for genetic permission to follow a diet rich in donuts and other sugary bakery goods. Nevertheless, people on the old-fashioned diet do spout off that they feel great and are losing weight (Miller, 2018). What gives? Could it truly be that genetics gave an insight or was it just following a healthy diet?

The successes (and not all people see success!) are not likely the result of properly matching diets to genotype. A recent and thorough study out of Stanford University, published in the Journal of the American Medical Association (JAMA), revealed that matching diets to genotypes does not give a person a huge advantage in weight loss (Gardner et al., 2018). Regardless of a match or not, participants lost weight. Eating healthy diets drove the weight loss. What this study does show is that we still have a lot to learn about the molecular underpinnings of weight loss and cannot rely on recommendations based solely on genetics.

If we look deeper into the biology of weight gain/loss, it is messier than my face after an encounter with delectable lemon curd filled donut. There are many reasons for the messiness; here are just a few:

1. People can lose weight based on the power of suggestion.

Yes, the power of suggestion is truly remarkable. In a study, two groups of women in the same profession were either told that their current level of activity met the surgeon general’s definition of an active lifestyle or were not given that info at all (Spiegel, 2008). After one month, the group informed about the surgeon general’s definition lost weight but had not increased their activity levels. The authors attributed the weight loss to a change in mindset. Quick! I need a doc or dietician to tell me that donuts can induce weight loss!

2. Genes can be turned on or off.

Research has shown that healthy lifestyle habits continually beat the genetic code predictions (Wang et al., 2018). It may sound unbelievable, but genes can be turned off or on before we are even born or in response to current environment (Youngson & Morris, 2013). Simple genetic tests may not be discerning which of these “make me fat now” genes are on or off.

3. The bacteria in our gut could be playing a role in weight loss.

In case you were not aware, our intestines are full of bacteria. In mice, researchers found that the guts of obese individuals were populated with certain types of bacteria (Ley et al., 2005). Soon after, it was learned that skinny mice could become obese if given the gut bacteria from fat mice (Turnbaugh et al., 2006). These early findings opened the flood gates to research looking at the contributions of gut bacteria in weight loss for humans. Guess what? Research shows that if our gut is populated by certain types of bacteria, it may give us an edge on losing weight (Hjorth et al., 2017; Youngson & Morris, 2013). There is still much to be learned, though, and some members of the research community are even calling these hopeful early findings into question (Begley, 2016).

It turns out that there is much to consider (and much unknown still) when it comes to factors that could affect our girth. Ugh! There must be a simpler way to help us better gauge our biological response to diets or even forecast if a diet will work.

Good news everybody! Proteomics (i.e., looking at the proteins in our body) may be the answer. Proteins (not genes) carry out the bulk of the metabolism work that happens at the molecular level. Already, technology has allowed us to look at the biological changes of least 5,000 proteins simultaneously. Initial work has shown promise in showing us how our bodies respond to diets (Oller Moreno et al., 2018) and indicated when a diet will be a huge failure (Thrush et al., 2017).

I may not be able to continue my love affair with the seductive donut as I get older without paying the consequences of increased mass. However, it is good to know that we may one day have the health insights necessary to better predict a diet where I might be able to have the occasional delectable gooey donut without a longer-term commitment to it.



Begley, S. (2016, September 22). Is the gut microbiome an important cause of obesity? STAT. Retrieved from

Gardner, C. D., Trepanowski, J. F., Del Gobbo, L. C., Hauser, M. E., Rigdon, J., Ioannidis, J. P. A., . . . King, A. C. (2018). Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion: The DIETFITS Randomized Clinical Trial. JAMA, 319(7), 667-679. doi:10.1001/jama.2018.0245

Hjorth, M. F., Roager, H. M., Larsen, T. M., Poulsen, S. K., Licht, T. R., Bahl, M. I., . . . Astrup, A. (2017). Pre-treatment microbial Prevotella-to-Bacteroides ratio, determines body fat loss success during a 6-month randomized controlled diet intervention. Int J Obes (Lond). doi:10.1038/ijo.2017.220

Ley, R. E., Backhed, F., Turnbaugh, P., Lozupone, C. A., Knight, R. D., & Gordon, J. I. (2005). Obesity alters gut microbial ecology. Proc Natl Acad Sci U S A, 102(31), 11070-11075. doi:10.1073/pnas.0504978102

Miller A. (2018, January 16). Should You Take a Genetic Test to Find the Best Diet for You? U.S.News. Retrieved from

Oller Moreno, S., Cominetti, O., Nunez Galindo, A., Irincheeva, I., Corthesy, J., Astrup, A., . . . Dayon, L. (2018). The differential plasma proteome of obese and overweight individuals undergoing a nutritional weight loss and maintenance intervention. Proteomics Clin Appl, 12(1). doi:10.1002/prca.201600150

Robbins, R. (2016, November 3). Genetic tests promised to help me achieve peak fitness. What I got was a fiasco. STAT. Retrieved from

Spiegel, A. (2008, January3). Hotel Maids Challenge the Placebo Effect. NPR. Retrieved from

Thrush, A. B., Antoun, G., Nikpay, M., Patten, D. A., DeVlugt, C., Mauger, J. F., . . . Harper, M. E. (2017). Diet-resistant obesity is characterized by a distinct plasma proteomic signature and impaired muscle fiber metabolism. Int J Obes (Lond). doi:10.1038/ijo.2017.286

Turnbaugh, P. J., Ley, R. E., Mahowald, M. A., Magrini, V., Mardis, E. R., & Gordon, J. I. (2006). An obesity-associated gut microbiome with increased capacity for energy harvest. Nature, 444(7122), 1027-1031. doi:10.1038/nature05414

Wang, T., Heianza, Y., Sun, D., Huang, T., Ma, W., Rimm, E. B., . . . Qi, L. (2018). Improving adherence to healthy dietary patterns, genetic risk, and long term weight gain: gene-diet interaction analysis in two prospective cohort studies. BMJ, 360, j5644. doi:10.1136/bmj.j5644

Youngson, N. A., & Morris, M. J. (2013). What obesity research tells us about epigenetic mechanisms. Philos Trans R Soc Lond B Biol Sci, 368(1609), 20110337. doi:10.1098/rstb.2011.0337