How to Read Nutrition Research Like a Dietitian
And what that popular article on the latest metabolism study really means.
The New York Times published an article on August 12, 2021 that had all my friends, clients, and family members asking me if it’s true that nothing changes in our metabolism between ages 20 to 60. In order to give them an accurate answer, I read through the article and then went directly to the source — the research paper behind all of the hype. What did I come up with?
First, this paper — which the headline presented like the end all, be all of research on human metabolism — is just one study. While the results are interesting and will help guide future research on metabolism, they are just one set of results. Not the thing you should hang your hat on. What they really reveal is just how little we know about human metabolism and how much we have to learn moving forward. There’s no clinical application to the findings — meaning, I’m not going to start treating my 20-something patients the same way I treat my 50-something patients. In fact, I don’t treat any of my patients the same because we’re all individuals. There are several conditions, lifestyle choices, and medications that can hasten or slow your metabolism both in childhood and adulthood.
People are constantly looking for answers about weight loss and what’s going on in their bodies, and with dozens of new diets coming out each month and celebs and influencers alike telling us to “eat this not that” everyone is confused. So what’s the best approach to content that claims to have found the magic bullet to all that ails you? Keep reading for a crash course in how to interpret nutrition info, for real.
The Most Important Step: Find the original research paper.
Whenever one of these articles comes out in the media, the very first thing I do is locate the original research paper. Usually the link is embedded in the article itself. If not, a quick search in Google Scholar does the trick. Sometimes research papers aren’t accessible due to paywalls. Check out your local library’s resources or contact one of the authors. More often than not, they’ll send you the article for free! If you have zero energy to go that route, contact a registered dietitian to do the work for you.
You’ve found the paper. Now what should you look for?
Who published the study?
Look for peer-reviewed original research articles that have been published in a reputable journal. If something says “abstract,” it probably hasn’t been peer-reviewed just yet and I don’t recommend getting too excited about the findings. While abstracts are interesting and for this reason often end up in headlines, it’s important to wait to see what the scientists who review them have to say.
Some reputable journals include:
- The Journal of the American Medical Association (JAMA)
- The Journal of the Academy of Nutrition and Dietetics (JAND)
- British Medical Journal (BMJ)
- Clinical Nutrition, Advances in Nutrition
- American Journal of Clinical Nutrition
- Annual Review of Nutrition, Obesity, Nature, Science
Is the research new?
Peer-reviewed journals frequently publish “novel research,” which is to say, brand-new research that may or may not be repeatable in future studies. Like abstracts, novel research is interesting and helps to guide future research, but I don’t recommend using it to guide you in changing your whole diet.
Who paid for the research?
Check out the Sources of Funding section. A lot of companies will pay for research. This tale is as old as time in the food and beverage industry. If a paper comes out claiming that sunflower seeds will cure cancer, it’s a good idea to check and see if it was funded by the sunflower farmers of America. I’ll let you draw your own conclusions on how trustworthy results are when the company trying to sell the product is footing the bill.
What is the design of the study?
Randomized Controlled Trials are the gold standard for research. They divide participants into two groups — the experimental group who receives the intervention and the control group who do not — and compare the two groups over a period of time. But this type of study isn’t always possible when it comes to nutrition research from an ethical standpoint. For instance, if you suspect bacon gives people cancer it would be unethical to give one group of people bacon every day and potentially give them cancer. Instead, nutrition studies are typically observational. This means that researchers are simply observing without intervention or manipulation. There are many different types of observational studies.
How can you determine if the study you’re looking at has a strong study design? Check out the Hierarchy of Evidence. In general, cohort studies show more powerful results than other forms of observational research because they follow a group of people over time (often over decades) versus looking back at things that have already occurred or at just one single point in time
How big is the study?
In general, bigger is better. A study of 20 people is not going to translate to the population at large. If I see a study with greater than 1,000 participants, I’m interested. If it’s a large cohort study with greater than 20,000 participants, I’m very interested.
Was the study done on animals or humans?
Animal studies aren’t all that helpful when it comes to guiding clinical recommendations in humans. If the study is a human study, check out the population involved in the study — head to the Results section to find this info. Usually the study population will be summarized in a table making it easy to read over quickly. If the population isn’t very diverse, the results probably aren’t going to translate to the population at large
Was the data reported self-reported by participants?
If so, how accurate do you think the info is that these participants are reporting? Let me ask you this: If you had to keep a food journal every single day for 3 months, do you think there’s a chance you might forget to log a day or two and decide to just make up a few things? To fudge a few numbers? And what about portion sizes? Are you measuring down to the ounce? Or just eyeballing 4 ounces?These little recording errors can drastically change results. If you see that a study is based on self-reported data, question the accuracy of the findings.
Was a validated tool used to collect the information?
Validated tools are tools that have been confirmed to measure the thing we are trying to measure accurately and reliably. Think about this: You can have eight bathroom scales in your house that all show different results if they aren’t all calibrated properly. These scales are neither accurate or reliable until they’ve been calibrated and until it has been confirmed that they measure weight accurately.
What was the study duration?
If you’re looking at the impact of a certain diet on weight loss, putting participants on the diet and measuring weight loss for 3 months isn’t very meaningful. Why? What if they lose weight rapidly for those 3 months and then suddenly plateau or begin gaining weight? The longer the duration of the study, the more we know about whatever it is that’s being studied.
What are the results?
What did the researchers find? Were any of the findings statistically significant? (The paper will say this.) How do the results compare to other similar studies?
Read the Discussion and Limitations
The Discussion section is where the researchers can talk about their results. They can get into reasons why they think certain results may or may not have occurred. The results sections shows the facts, the discussion sections gets into what the researchers think about those facts. What were the limitations of the study? Luckily, the authors will point these out to you in the discussion. Oftentimes the authors will mention things like small sample size or lack of diversity in the study population
What did the researchers conclude?
Researchers are pretty blunt — they’ll usually state “further research is needed” if further research is needed to help support their findings.
Never, ever trust just one study. There is no golden ticket. Nutrition is a newer science and the research is always evolving. If you have questions about the hot research of the week, talk to a registered dietitian. We are trained in the art of reading original research articles and distilling the deets for our clients and patients in a way that can (or cannot) be applied to everyday life!
Vanessa Rissetto received her MS in Marketing at NYU and completed her Dietetic Internship at Mount Sinai Hospital where she worked as a Senior Dietitian for five years. She is certified in Adult Weight Management (Levels I & II) by the Academy of Nutrition and Dietetics, and the founder of Culina Health. Her work in private practice also includes treatment of GI disorders, bariatric surgery, weight management, PCOS, and family nutrition. She loves helping clients take an active role in their health journey, motivating them and ensuring that they always achieve success. Vanessa was named by one of the top 5 black nutritionists that will change the way you think about food by Essence magazine. Vanessa lives in Hoboken NJ with her husband, two kids and their new goldendoodle Freddie. An exercise enthusiast, she is always up for a class as long as it's after she rides her Peloton.
*This article was written and/or reviewed by an independent registered dietitian nutritionist.