David Ludwig MD, PhD

Adults (average BMI 25) ate:

2 cups fruit daily or none for 8 wk

(8-wk "washout period" - pretty good, all considered)

Fruit (including bananas, apples, oranges, watermelon)

👉 ⬆️ some blood nutrients
👉BUT insulin resistance better without the fruit

cdn.nutrition.org/article/S247...

The notion of "ultra-processed" food is so complicated, not even @fda.gov knows how to define it.

There's a simpler way. Focus on the main health offenders:

👉Refined grains, sugar, and other highly processed carbs.

In print today.
Free online access (requires email) wapo.st/3WuPHGJ

Opinion | Targeting ultra-processed food repeats America’s missteps on nutrition MAHA blames this food group for chronic disease. Nutrition science isn’t so simple.

Will targeting "ultra-processed food" in national nutrition policy make Americans (and the rest of the world) healthier?

I argue there is a better way
wapo.st/3WuPHGJ

In @natmed.nature.com, Mary Putt (@dbei-upenn.bsky.social), @davidludwigmd.bsky.social & Walter Willett (@hsph.harvard.edu) discuss concerns for the validity of short-term dietary crossover trials www.nature.com/articles/s41...

YouTube video by Nick Norwitz This Will Change Your Mind on Ultra-Processed Foods (Harvard MD PhDs Discuss)

Target "ultra-processed foods" to tackle the chronic disease epidemic .... What could possibly go wrong? My 50 min convo with Nick Norwitz www.youtube.com/watch?v=JAPg...

YouTube video by Metabolic Mind The Ultra-Processed Food Debate: Science, Bias, & Truth

When you have 50 min ...

The investigative journalist Gary Taubes and I discuss the notion of ultra-processed foods, the sorry state of nutrition research ... and how we can inch toward truth when scientific paradigms collide.
www.youtube.com/watch?v=PfOb...

Rising temperatures increase added sugar intake disproportionately in disadvantaged groups in the USA - Nature Climate Change Few studies have evaluated how climate change may affect dietary habits and nutritional health. Here, using transaction data in the USA, the authors show that added sugar consumption increases with te...

The hotter it gets, the more sugar we consume ... mainly in the form of sugary drinks.

👉Let's find other ways to keep cool
www.nature.com/articles/s41...

Ultraprocessed Food on an Ultrafast Track | NEJM The Nova food-classification system has advanced efforts to address modern diets of highly processed foods. But it’s unclear whether it can be codified at a national level to support public health.

Should national nutrition policy target "Ultra-Processed Foods" as many advocate?

I consider concerns in @nejm.org

Like 'The Emperor's New Clothes'

👉We're rolling out a red carpet, but the evidence is threadbare!

NEJM: www.nejm.org/doi/10.1056/...

BLOG (no paywall) medium.com/@davidludwig...

Certified for 1-oar rowing today in Hellerup, Denmark (where we live part time).

I don't believe I have Viking ancestors, but if I do, they would be proud. 😀

YouTube video by Metabolic Mind The Truth About Nutrition Science: Is The Government Getting it Wrong?

My 1-hour (40 min on 1.5 x 😀) deep dive on the diets, nutrition research, and where we go from here ... with journalist Gary Taubes, hosted by @metabolicmind.bsky.social

Debating the Carbohydrate-Insulin Model with John Speakman in Cell Metabolism.

Letter-to-the-Editor (open access) authors.elsevier.com/a/1lCYr5WXUl...

Reply www.cell.com/cell-metabol...

β-hydroxybutyrate inhibits Plasmodium falciparum development and confers protection against malaria in mice - Nature Metabolism A ketogenic diet and the ketone body β-hydroxybutyrate are shown to confer resistance to malaria in mice by inducing metabolic reprogramming in Plasmodium parasites, suggesting a dietary strategy for ...

Avoid carbs to prevent malaria?

Preliminary evidence suggests maybe so ...
www.nature.com/articles/s42...

NIH Has A Nutrition Problem (Part 2 ) If you want to demonstrate that a plant-based diet is better than a ketogenic diet (or that ultra-processed food makes us overeat), these critical design flaws will help

“Pathological” science?

To solve the chronic disease epidemics, we need to get the research right.

Gary Taubes on the failure of nutrition science to correct fatally flawed diet trials … and avoid these blunders in the first place.

Medical Nutrition Therapy in Dermatological Diseases: A Joint Consensus Statement of the Italian Association of Dietetics and Clinical Nutrition (ADI), the Italian Society of Dermatology and Sexually ... Summary Dermatological diseases such as acne, hidradenitis suppurativa (HS), and psoriasis are driven by chronic inflammation and oxidative stress. Emerging evidence highlights the role of nutrition i...

Italian professional societies consensus report on diet and skin disease.

Data are preliminary but promising:

👉Low-carb ketogenic diet may help acne, psoriasis
link.springer.com/article/10.1...

NIH Nutrition Research Takes it on the Chin A "top" nutrition researcher exits, followed by two damning articles challenging his studies and claiming that a flagship $170 million NIH initiative is "designed to fail."

NIH Nutrition Research Takes it on the Chin

Gary Taubes' deep dive into the largest nutrition trial in years.

#DesignedToFail
uncertaintyprinciples.substack.com/p/nih-nutrit...

Short-term diet trials are designed to fail - Center for Health Incentives and Behavioral Economics (CHIBE) This article critiques short-term diet trials, arguing they are inadequate for understanding nutrition's impact on chronic disease.

What diet works best to prevent obesity, diabetes, cardiovascular disease, cancer and Alzheimer’s? Answers remain elusive...But why? The problem may be rooted in poorly designed nutrition research. @davidludwigmd.bsky.social chibe.upenn.edu/news/short-t...

Designed to Fail: Why Short-term Diet Trials Cannot Solve the Epidemics of Chronic Disease A version of this essay was published in STAT News First Opinion on April 22

Designed to Fail:

Why short-term diet trials cannot solve the epidemics of chronic disease.

👉New blog post (no paywall)

A researcher looking at data

The effects of an intervention may take time to develop and persist after discontinuation, producing wash-in and washout effects that threaten trial validity.

This article describes the nature of this bias in nutrition research as an illustrative case
www.bmj.com/content/389/...

Short-term diet trials are designed to fail Does ultra-processed food cause obesity? Maybe, but we’ll never know from short-term trials.

In an associated opinion piece in STAT News (www.statnews.com/2025/04/22/n...),

Designed to Fail: Why Short-term Diet Trials Cannot Solve the Epidemics of Chronic Disease A version of this essay was published in STAT News First Opinion on April 22

Designed to Fail:

Why short-term diet trials cannot solve the epidemics of chronic disease.

👉New blog post (no paywall)

Wash-in and washout effects: mitigating bias in short term dietary and other trials Short term trials with surrogate measures instead of hard outcomes are often used to study chronic diseases. The effects of an intervention may, however, take time to develop and persist after discont...

Designed to Fail

Why short-term trials, like those in the $170M Nutrition for Precision Health initiative, cannot solve the epidemics of chronic disease.

Study in BMJ with Walt Willett and Mary Putt www.bmj.com/content/389/...

Opinion in @statnews.com
www.statnews.com/2025/04/22/n...

Tumor metabolism as a factor affecting diversity in cancer cachexia | American Journal of Physiology-Cell Physiology | American Physiological Society Cancer cachexia is a multifaceted metabolic syndrome characterized by muscle wasting, fat redistribution, and metabolic dysregulation, commonly associated with advanced cancer but sometimes also evide...

Fascinating review cancer cell metabolism.

Most cancer treatments harm the "host" (ie, the patient), in addition to the tumor.

With knowledge of metabolism, we might be able to:

👉Attack the tumor AND
👉Support the host

Global Effect of Cardiovascular Risk Factors on Lifetime Estimates | NEJM Five risk factors account for approximately 50% of the global burden of cardiovascular disease. How the presence or absence of classic risk factors affects lifetime estimates of cardiovascular dise...

Important paper on risk factors and life expectancy worldwide.

Action mostly with smoking, diabetes, BP, weight. Less so with LDL chol.

(Probably written by a committee: 👉"modification of smoking ... was associated with the most additional life-years free of death")
www.nejm.org/doi/abs/10.1...

Most U.S. infant formulas contain mainly added sugars, posing a serious risk to babies' health, researchers say Most infant formulas in the U.S. contain mostly added sugars instead of natural lactose, which experts say can harm early development, a new study shows.

“Infants may consume upwards of 60 grams of added sugars per day, or the equivalent of two soft drinks per day if they are entirely formula-fed,” researchers say in the study, published yesterday [Feb. 24, 2025] in the Journal of Food Composition and Analysis.

usrtk.org/healthwire/i...

Anti-depressant therapy for Danish winter.

👉Hellerup harbor, water temp 2° C

Will a Low-Carb Diet Reduce Racial & Ethnic Health Disparities? Coauthored with Nicholas Norwitz, Diana Thomas, and Cara Ebbeling. Image modified from ChatGTP by Mr Andrew Degryse

Will a Low-Carb Diet Reduce Racial & Ethnic Health Disparities?

No paywall at this link:

NOON, Denmark. Circa solstice. View to the South.

In case you were wondering, that moderately bright object about 10° above the horizon is ... the sun 😲

Last day of 5-day fast. Nice ketone bump.

Overall, went well. Day 3 was the hardest. Now feeling good, little hunger, consistent energy.

Admittedly, looking forward to first meal this afternoon. Will build up slowly, 3 days.

PLANS: 1 day fast every couple weeks. Longer fast every 3 months.

Frontiers | Effect of carbohydrate restriction on body weight in overweight and obese adults: a systematic review and dose–response meta-analysis of 110 randomized controlled trials IntroductionCarbohydrate-restricted diets are one of the most effective dietary interventions for weight loss. However, the optimum carbohydrate intake for i...

The obesity guideline has extensive detail comparing various drugs (both tables).

But not even the most rudimentary comparison of diets.

This despite multiple meta-analyses suggesting efficacy of carbohydrate restriction.
www.frontiersin.org/journals/nut...

8. Obesity and Weight Management for the Prevention and Treatment of Type 2 Diabetes: Standards of Care in Diabetes–2025 The American Diabetes Association (ADA) “Standards of Care in Diabetes” includes the ADA’s current clinical practice recommendations and is intended to pro

New American Diabetes Assoc guidelines for obesity in Type 2 diabetes. Once again:

"500–750 kcal/day energy deficit is recommended" (hasn't this been tried for a century???)

Regarding diet, "no single way is best"

👉Low-carb diets mentioned exactly ... 0 times
diabetesjournals.org/care/article...