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Breaking the code: What DNA can tell you about weight loss

by Trish Brown, MS, CGC

Trish Brown, MS, CGC is a member of the Precision Medicine and Industry Special Interest Groups, and is currently the Director of Payer Partnerships at Illumina.


What is the secret to being successful on a diet?

It’s a question that people have been trying to answer for years and a topic that is frustrating for many.   Why do diets seem to work for some people and not others? How come some people eat whatever they want and never gain a pound while others diet and continue to struggle with weight? People swear by diets like keto, paleo or fasting, touting weight loss of tens or even hundreds of pounds, but when others attempt these diets, they see no results. Why?

In hopes of getting clearer answers on weight loss, people are turning to DNA testing, but it’s a controversial topic. In 2014, the Academy of Nutrition and Dietetics came out with a position statement saying that there is no evidence that DNA can provide you with information on what to eat and how to exercise to lose weight. However, they’re actually taking a second look at that analysis because since they made that statement 6 years ago, there’s been an 84% increase in the number of studies that have looked at the value of DNA testing with diet and exercise.

For example, researchers looked at genetic testing as a way to identify who would successfully maintain weight loss 2-5 years after bariatric surgery, and several studies have been published that support the idea that certain genetic factors play a role in long term success of keeping weight off.1,2 A systematic review of research showed that undergoing genetic testing itself, regardless of  results, was a catalyst for behavior change and weight loss when coupled with lifestyle modification recommendations.3  So, what we know is that while the results from DNA tests cannot provide a specific roadmap of what an individual needs to do to lose weight, genetics can reveal some information that could help on a weight loss journey.

How does DNA testing relate to nutrition?

Genes are the instructions that code for proteins and enzymes that break down food and extract the sugars, fats, vitamins and other nutritional elements. More proteins and enzymes carry the energy and nutritional elements throughout the body and determine if they will be used or stored. There are more than 100 genes involved in this complex process. As a result, rarely would just one gene cause someone to be overweight, underweight or to have difficulty exercising. It is for this reason that genetic testing may not result in one clear diet approach.

Some of the nutrition and exercise advice you might get from a DNA test can include:

  • Eat less fast food
  • Eat more vegetables
  • Don’t eat dairy products
  • Limit your consumption of grilled foods
  • Increase your intake of Omega 3 fatty acids
  • Keep your sodium intake low, you are at higher risk for high blood pressure
  • Based on your average aerobic profile, cross train between both power and endurance activities to improve your aerobic potential
  • Your recovery time is likely to be slower than average; increase the time between workouts for maximum recovery

Because of the complex interaction between genes and environment, some companies that offer diet and DNA testing services may also offer other blood tests, gut microorganism testing and use lifestyle questionnaires to learn about your personal beliefs regarding food.

Can I trust the advice that a DNA test is giving me on nutrition and exercise?

DNA testing for weight loss purposes has not been well studied and no weight-loss related DNA test is FDA approved at this time.

Research is moving at a rapid pace, and our understanding of what a particular gene might do can evolve over time, so the meaning of your DNA test results may also change.  Before embarking on testing, you need to understand these concerns and be aware that as noted above, the advice that is given as a result of these genetic tests is often just a common-sense approach to weight loss and exercise.

Some people love that.  Individuals like seeing their genetic data, and it can feel empowering to reinforce observations that you’ve made about yourself already. Others may be disappointed and feel like they didn’t learn anything new. If you have any doubts or want to understand what type of information a particular test might provide, talking to a genetic counselor can help you decide if you want testing, as well as help you understand any results you might already have.

Will DNA testing give me the answers I want?

No DNA test will give you the perfect road map to weight loss or exercise, but it may give you some common-sense advice that is personalized for you, to the degree it is scientifically possible. If you are considering DNA testing to determine how to diet or exercise, you first should think about whether or not you really need the test to get the information you want. It is likely that if you are trying to lose weight, you have tried different ways before and you have a good sense of what does and does not work for you and your body. The reason your diet may have failed in the past could be due to your body’s natural weight. Your body has a natural set point for weight, usually within a few pounds, that it tends to stay within. While it is possible to change this setpoint, it can be challenging and DNA testing should not be used as a quick fix.

Advice for DNA testing

If you decide that DNA testing is for you, we recommend a few things:

  1. Select a DNA diet company that will answer your questions about privacy and the type of information you can learn from this test
  2. Ask whether they have customer support available
  3. Find out whether they have genetic counselors available to discuss your results
  4. Ask whether they have nutrition counselors that have been trained in dealing with DNA results
  5. Do your research to see if the company has had issues with the Federal Trade Commission (FTC), FDA or other groups

You want to be sure that when you receive your results you are not alone in interpreting what the results mean and trying to understand how this impacts your body and what you should eat. These tests can also give you other information like your risk for developing certain diseases, so you need to think about whether you want to know this information. Finally, it is important to manage your own expectations. Are you going to be discouraged if your results give you information you already knew or are you going to be glad that you learned this data about your DNA?

To find a genetic counselor who can help you decide if DNA testing is right for you visit www.findageneticcounselor.com 


 

  1. de Toro-Martín J, Guénard F, Tchernof A, Pérusse L, Marceau S, Vohl MC. Polygenic risk score for predicting weight loss after bariatric surgery. JCI Insight. 2018;3(17):e122011. Published 2018 Sep 6. doi:10.1172/jci.insight.122011
  2. Ciudin A, Fidilio E, Ortiz A, et al. Genetic Testing to Predict Weight Loss and Diabetes Remission and Long-Term Sustainability after Bariatric Surgery: A Pilot Study. J Clin Med. 2019;8(7):964. Published 2019 Jul 3. doi:10.3390/jcm8070964
  3. Horne J, Madill J, O'Connor C, Shelley J, Gilliland J. A Systematic Review of Genetic Testing and Lifestyle Behaviour Change: Are We Using High-Quality Genetic Interventions and Considering Behaviour Change Theory?. Lifestyle Genom. 2018;11(1):49-63. doi:10.1159/000488086
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