Kevin Hall

At a glance

• Kevin Hall is an American metabolism researcher who spent many years at the National Institutes of Health (NIH), where he ran tightly controlled feeding studies. He left the NIH in 2025.
• His best-known study (Cell Metabolism, 2019) had inpatient volunteers eat an ultra-processed diet for two weeks and a minimally processed diet for two weeks. On the ultra-processed diet they ate about 500 kcal more per day and gained weight.
• He also followed contestants from the TV show The Biggest Loser and showed that their resting metabolism remained markedly lower than expected years after their weight loss.
• He compared a plant-based low-fat diet with an animal-based ketogenic diet (Nature Medicine, 2021): on the low-fat diet people spontaneously ate fewer calories.
• Using mathematical models of body weight, he built the NIH Body Weight Planner. With journalist Julia Belluz he wrote the book Food Intelligence (2025).
• For longevity, his work shows how strongly our environment and the degree of food processing steer eating behaviour, regardless of willpower.
• Takeaway: build your meals mainly from minimally processed foods; that makes it easier not to overeat without trying.