Our rules for health claims

  • Every health claim on this site links to a study or an official statistic.
  • When a study only shows a link (observational research), we say "linked to," not "causes."
  • We say how big and how strong each study is, including when it's small.
  • WPU itself hasn't been studied yet as a program. We're collecting data from the founding cohort and will publish what we find.

Claim by claim

Lifestyle change can prevent type 2 diabetes in people at high risk.

In the Diabetes Prevention Program trial (3,234 adults with prediabetes, followed for about 2.8 years), an intensive lifestyle program cut new cases of type 2 diabetes by 58% compared with placebo. Metformin cut them by 31%.

Evidence type: Randomized controlled trial · Knowler et al., N Engl J Med, 2002

The quality of a plant-based diet matters.

In about 209,000 US adults, a healthful plant-based eating pattern was linked to about 25% lower coronary heart disease risk, while a plant-based pattern high in refined grains, sweets, and sugary drinks was linked to about 32% higher risk.

Evidence type: Large observational study (shows a link, not cause) · Satija et al., J Am Coll Cardiol, 2017

Fiber from whole plant foods is linked to longer life.

Across many studies, people eating the most fiber had 15–30% lower all-cause and cardiovascular death rates than people eating the least, with the largest benefit at about 25–29 grams a day.

Evidence type: Systematic review and meta-analyses · Reynolds et al., Lancet, 2019

Vegetarian eaters tend to live longer.

In the Adventist Health Study 2, vegetarians as a group had about 12% lower all-cause mortality than non-vegetarians over the study period.

Evidence type: Observational cohort study (shows a link, not cause) · Orlich et al., JAMA Intern Med, 2013

A plant-based diet can improve blood sugar in type 2 diabetes.

In a 22-week trial of 99 people with type 2 diabetes, a low-fat vegan diet lowered HbA1c by 0.96 points versus 0.56 on a standard diabetes diet, and 43% versus 26% reduced their diabetes medication.

Evidence type: Randomized controlled trial (small, short) · Barnard et al., Diabetes Care, 2006

Intensive lifestyle change can slow, and sometimes partly reverse, heart disease.

In a small 5-year trial (35 people completed), intensive lifestyle changes including a very low-fat vegetarian diet led to modest regression of coronary artery narrowing, while narrowing worsened in the control group. The lifestyle group also had fewer cardiac events.

Evidence type: Randomized trial (very small) · Ornish et al., JAMA, 1998

Changing together works better than changing alone.

People who joined a weight-loss program with friends and received social-support training were more likely to finish (95% vs 76%) and to keep the weight off (66% vs 24%) than people who joined alone with standard treatment.

Evidence type: Randomized controlled trial · Wing & Jeffery, J Consult Clin Psychol, 1999

Cooking classes can help people eat better.

A review of 28 cooking and home food preparation programs for adults found results suggesting a positive influence on eating behavior, and called for better long-term studies.

Evidence type: Systematic review (mixed-quality studies) · Reicks et al., J Nutr Educ Behav, 2014

The longest-lived communities eat mostly plants, together.

A review of five "Blue Zones" with unusually long-lived populations describes shared traits including mostly plant-based diets, daily movement, and strong social and faith communities.

Evidence type: Descriptive review (no new data) · Buettner & Skemp, Am J Lifestyle Med, 2016

Chronic disease is common and serious.

115.2 million US adults, more than 2 in 5, have prediabetes, and 8 in 10 of them don't know it. Heart disease is the leading cause of death for men, women, and most racial and ethnic groups in the US.

Evidence type: Official public health statistics · CDC prediabetes statistics and heart disease facts

What we don't claim

WPU is an education and behavior-change program, not medical treatment. We don't promise weight loss, disease reversal, or that anyone can stop medication. If your numbers improve, your doctor may adjust your doses; never change medication on your own.

Found an error, or a better study? Write to [email protected].