The Diet Doctor policy for evidence-based guides

Our evidence-based guides are based on the currently best available scientific evidence. There are in-line references supporting each key statement or recommendations about diagnosis, treatment or prognosis. To view these references, click the grey note symbols.1
The guides are reviewed and fact-checked by medical doctors or researchers who are experts on the specific topics (find our medical review board here).

We grade the quality of the evidence based on a specified policy, where systematic reviews of RCTs is the highest level, followed by RCTs. Observational evidence based on weak correlations is ranked low, as it is likely to be random and misleading.2

The language in the guides has to reflect the quality of the evidence supporting a claim. We must make it completely clear if a claim lacks robust scientific evidence and is based mostly on a weak foundation, e.g. opinions, clinical experience or anecdotes. The strength of a recommendation should be clear from the language used.

Guides should make it clear who the target audience is (e.g. adults with type 2 diabetes, adults with obesity) and for whom the evidence applies.


Our guides can not contain any statements that are contradicted by science. If a topic is currently controversial, with a likely majority of experts still having a different opinion than the one we recommend, the guide should contain a disclaimer discussing this.

The disclaimer should contain the scientific basis for dissenting, with references, and discuss potential strengths and weaknesses of the core evidence for the different positions.


Our evidence-based guides are updated to reflect and reference the latest science on the topic. This science is identified through searching the medical literature on the core topic, and through keeping up-to-date with major new studies on the topic.

We pay special attention to carefully updating controversial topics regularly, and deciding whether new information means that our position should be updated or changed in any way. When doing major updates of our guides, this is noted, so that visitors can see when major updates happened and what they contain.


To stay as unbiased as we can, we show no ads, sell no products and take no industry money. All authors of evidence-based guides need to finish a declaration of potential conflicts of interest, reflecting this, and update it at least once per year. This declaration should be easy to find on their author page, that you can find by clicking on their name.

As our site and our optional membership primarily focuses on low-carb diets, we may be biased in favor of this. To some degree the guides will always reflect the perspective of the authors, as complete objectivity is hard to achieve. To limit bias we pay special attention to make sure that we include information about potential dangers, side effects and drawbacks of low-carb diets in our guides, and that we don’t exaggerate benefits or evidence beyond what is supported by science.

On a related topic, we need to keep firmly in mind that no one treatment works for everything, certainly not on its own. When there are other important factors or treatments than low carb, even in an area where low carb can be effective (e.g. for weight loss), we should mention this.

To reduce mistakes caused by unconscious bias, we try to obtain feedback from thoughtful experts with a different point of view, and try to use their feedback to improve our understanding and our guides.


While we base our guides on scientific evidence, not every question can be answered by science, certainly not by a science as imperfect as the nutritional science of today.3 There is also the question of what to do with the knowledge that we have, and to answer that it is often necessary to rely on values.

At Diet Doctor we are guided by our core values.4 We aim to make our guides practically useful, trustworthy, inspiring, simple and empowering for people. We try to maximize the chance of benefit while minimizing the risk of harm.

For the prevention and treatment of many chronic diseases and for the promotion of wellbeing, we try to emphasize lifestyle interventions that are likely to be effective and that have a long evolutionary history (e.g. old-fashioned natural foods, fasting, exercise, sleep) as first-line treatments.56

However, whenever drugs or surgery are clearly the first option, e.g. for many serious diseases like cancer, we make that very clear. We also aim to make it clear when medications are an important compliment to lifestyle interventions.

Final words

Finally, and obviously, the information we provide at is never intended to replace consultation with a qualified medical professional. Full disclaimer

If you find examples where we are not achieving our high standards as set forth in this guideline, please let us know by emailing We welcome your feedback as we constantly strive to improve to become the most trusted online health site, for accurate and reliable health information.

The overarching goal is for our evidence-based guides to be the best in the world on the topic. This requires making them very trustworthy from a scientific perspective, while still being simple to understand, practically useful and inspiring.



List of evidence-based guides and the latest updates

The Diet Doctor policy for grading scientific evidence

The science of low carb and keto

Medical review board

The search for “evidence-based” guidelines


Do you have comments on, objections to or suggested changes or additions to our guidelines? Feel free to email your suggestions to

  1. Yes, like this one. Occasionally, references and links may also be found directly in the text.

  2. Guide to observational vs. experimental studies

    Advances in Nutrition 2018: Limiting dependence on nonrandomized studies and improving randomized trials in human nutrition research: why and how

    JAMA 2018: The challenge of reforming nutritional epidemiologic research

    PLoS Medicine 2005: Why most published research findings are false

  3. Advances in Nutrition 2018: Limiting dependence on nonrandomized studies and improving randomized trials in human nutrition research: why and how

    JAMA 2018: The challenge of reforming nutritional epidemiologic research

    PLoS Medicine 2005: Why most published research findings are false

  4. The Diet Doctor values

  5. What is old-fashioned natural foods? We try to focus on foods that human ancestors have been eating for a long time. Foods with such a history going back thousands of years or ideally hundreds of thousands of years. We also try to focus on foods that are easily combined into a diet that is nutritionally complete.

  6. We focus primarily on lifestyle changes, rather than drugs, surgical interventions or other new and experimental treatments. We do this because we believe that effective lifestyle interventions are generally more likely to result in improved long-term health and wellbeing, and less likely to have unforeseen side effects, due to evolutionary principles.

    Furthermore, there is generally less financial incentives involved in promoting effective lifestyle interventions, and thus there is a shortage of well-produced information online, something that makes it possible for us to have a larger positive impact.